POLYMERISATION PROCESS

Abstract

A process for the ring-opening copolymerisation of epoxides with carbon dioxide for the preparation of a polycarbonate is described. Also described are catalysts useful in the aforementioned process. The heterobimetallic catalysts present a number of advantages over catalysts that have conventionally been used for this process.

Claims

1. A process for the preparation of a polycarbonate, the process comprising the following step: a) contacting carbon dioxide with at least one epoxide, wherein step a) is conducted in the presence of a compound of Formula I shown below: ##STR00150## wherein M.sup.1 is selected from the group consisting of a group 2 metal, a group 3 metal, a transition metal, a group 13 metal, a group 14 metal and a lanthanide; M.sup.2 is selected from a group 1 metal, a group 2 metal, a group 3 metal, a group 13 metal or a lanthanide; R.sup.1 is selected from (2-5C)alkylene, (2-5C)alkenylene and or (2-5C)alkynylene, wherein 0, 1 or 2 carbon atoms within any one of the said (2-5C)alkylene, (2-5C)alkenylene and (2-5C)alkynylene is replaced with a heteroatom selected from O and or N, and wherein any carbon, O or N atom within the said (2-5C)alkylene, (2-5C)alkenylene and (2-5C)alkynylene may be independently optionally substituted with one or more R.sup.x; each R.sup.x is independently selected from halo, hydroxy, cyano, nitro, (1-20C)alkyl, (2-20C)alkenyl, (2-20C)alkynyl, (1-20C)haloalkyl, (1-20C)alkoxy, aryl, heteroaryl and —NR.sup.xaR.sup.xb, where any aryl or heteroaryl in R.sup.x is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-20C)alkyl, (1-20C)haloalkyl or (1-20C)alkoxy, and where R.sup.xa and R.sup.xb are independently selected from hydrogen or (1-3C)alkyl, and/or two or more R.sup.x located on adjacent atoms are linked to one another, such that when taken in combination with the atoms to which they are attached, they form a monocyclic or bicyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system, wherein any of the said monocyclic or bicyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-20C)alkyl, (1-20C)haloalkyl and or (1-20C)alkoxy; each R.sup.2 is independently selected from absent, hydrogen, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl, aryl, aryl(1-2C)alkyl, heteroaryl, heteroaryl(1-2C)alkyl, —C(O)—R.sup.2a, —C(O)—OR.sup.2a ad or —C(O)—NR.sup.2aR.sup.2b, where any aryl, aryl(1-2C)alkyl, heteroaryl and heteroaryl(1-2C)alkyl in R.sup.2 is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl and or (1-4C)alkoxy, and where R.sup.2a and R.sup.2b are independently selected from hydrogen and (1-3C)alkyl; each X.sup.1 is independently selected from —CH—, —CR.sup.4—, —CH.sub.2—, —CHR.sup.4—, —CR.sup.4R.sup.4— and —PR.sup.4R.sup.4—, where each R.sup.4 is independently selected from (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl, aryl, aryl(1-2C)alkyl, heteroaryl or heteroaryl(1-2C)alkyl, where any aryl, aryl(1-2C)alkyl, heteroaryl and heteroaryl(1-2C)alkyl in R.sup.4 is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl and or (1-4C)alkoxy; E.sup.1 is C and E.sup.2 is O, S or N; or E.sup.1 is N and E.sup.2 is O; each R.sup.3 is independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl, (1-4C)alkoxy, aryl, aryl(1-2C)alkyl, heteroaryl, heteroaryl(1-2C)alkyl, —C(O)—R.sup.3a, —C(O)—OR.sup.3a, —O—C(O)—R.sup.3a, —C(O)—NR.sup.3aR.sup.3b, —N(R.sup.3a)C(O)—R.sup.3b or —NR.sup.3aR.sup.3b, where any aryl, aryl(1-2C)alkyl, heteroaryl and heteroaryl(1-2C)alkyl in R.sup.3 is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl or (1-4C)alkoxy, and where R.sup.3a and R.sup.3b are independently selected from hydrogen or (1-3C)alkyl; and/or two R.sup.3 located on adjacent atoms are linked to one another, such that when taken in combination with the atoms to which they are attached, they form a monocyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system, wherein any of the said monocyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl or (1-4C)alkoxy; each n is independently selected from 0, 1, 2 or 3; L.sup.1 and L.sup.2 are independently selected from absent, halo, nitrate, hydroxy, (1-20C)alkyl, (2-20C)alkenyl, (2-20C)alkynyl, (1-20C)heteroaliphatic, carbocyclyl, carbocyclyl(1-3C)alkyl, heterocyclyl, heterocyclyl(1-3C)alkyl, aryl, aryl(1-3C)alkyl, heteroaryl, heteroaryl(1-3C)alkyl, —O—C(O)—R.sup.a, —O—C(O)O—R.sup.a, —OP(O)(R.sup.a).sub.2, —P(O)(OR.sup.a).sub.2, —OR.sup.a, —O—S(O).sub.2—R.sup.a (e.g. triflate), —O—S(O)—(R.sup.a).sub.2, —O—S(O)—R.sup.a, —S(O)—R a, —S—C(O)—R.sup.a, —S—C(S)—O—R a, —N(H)S(O).sub.2—R.sup.a (e.g. triflamide), —N—(S(O).sub.2—R.sup.a).sub.2 (e.g. triflimide), —S—R.sup.a, —N(R.sup.a)—C(O)—R.sup.a, —C(O)—N(R.sup.a).sub.2, —N(R.sup.a).sub.2 or —O—Si(R.sup.a).sub.x(OR.sup.a).sub.y (where x and y are independently 0, 1, 2 or 3, with the proviso that x+y=3), in which any of the said (1-20C)alkyl, (2-20C)alkenyl, (2-20C)alkynyl, (1-20C)heteroaliphatic, carbocyclyl, carbocyclyl(1-3C)alkyl, heterocyclyl, heterocyclyl(1-3C)alkyl, aryl, aryl(1-3C)alkyl, heteroaryl and heteroaryl(1-3C)alkyl within L.sup.1 or L.sup.2 is optionally substituted with one or more R.sup.b, with the proviso that at least one of L.sup.1 and L.sup.2 is not absent; R.sup.a is independently selected from hydrogen, (1-25C)alkyl, (2-25C)alkenyl, (2-25C)alkynyl, (1-25C)heteroaliphatic, carbocyclyl, carbocyclyl(1-3C)alkyl, heterocyclyl, heterocyclyl(1-3C)alkyl, aryl, aryl(1-3C)alkyl, heteroaryl or heteroaryl(1-3C)alkyl, where any (1-25C)alkyl, (2-25C)alkenyl, (2-25C)alkynyl, (1-25C)heteroaliphatic, carbocyclyl, carbocyclyl(1-3C)alkyl, heterocyclyl, heterocyclyl(1-3C)alkyl, aryl, aryl(1-3C)alkyl, heteroaryl or heteroaryl(1-3C)alkyl present in R.sup.a is independently substituted with one or more groups independently selected from halo, cyano, nitro, amino, hydroxy, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl or (1-4C)alkoxy; each R.sup.b is independently substituted with one or more groups independently selected from halo, cyano, nitro, amino, hydroxy, (1-4C)alkyl, (1-4C)haloalkyl, (2-4C)alkenyl, (2-4C)alkynyl or (1-4C)alkoxy; G.sup.1 and G.sup.2 are independently selected from absent and a neutral or anionic donor ligand that is a Lewis base; Q has a structure according to Q-I or Q-II shown below: ##STR00151## each X.sup.2 is independently absent or (1-3C)alkylene, where said (1-3C)alkylene is optionally substituted with 1 or 2 groups independently selected from (1-2C)alkyl; each X.sup.3 is independently absent or (1-3C)alkylene, where said (1-3C)alkylene is optionally substituted with 1 or 2 groups independently selected from (1-2C)alkyl; each X.sup.4 is independently absent or methylene that is optionally substituted with 1 or 2 groups independently selected from (1-2C)alkyl; m is 1, 2, 3 or 4; each R.sup.5 is independently selected from hydrogen, halo, hydroxy, cyano, nitro, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl, (1-4C)alkoxy, aryl, aryl(1-2C)alkyl, heteroaryl, heteroaryl(1-2C)alkyl, —C(O)—R.sup.5a, —C(O)—OR.sup.5a, —O—C(O)—R.sup.5a, —C(O)—NR.sup.5aR.sup.5b, —N(R.sup.5a)C(O)—R.sup.5b or —NR.sup.5aR.sup.5b, where any aryl, aryl(1-2C)alkyl, heteroaryl and heteroaryl(1-2C)alkyl in R.sup.5 is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl or (1-4C)alkoxy, and where R.sup.5a and R.sup.5b are independently selected from hydrogen or (1-3C)alkyl, and/or two R.sup.5 located on adjacent atoms are linked to one another, such that when taken in combination with the atoms to which they are attached, they form a monocyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system, wherein any of the said monocyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl or (1-4C)alkoxy; each R.sup.6 is independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl, (1-4C)alkoxy, aryl, aryl(1-2C)alkyl, heteroaryl, heteroaryl(1-2C)alkyl, —C(O)—R.sup.6a, —C(O)—OR.sup.6a, —O—C(O)—R.sup.6a, —C(O)—NR.sup.6aR.sup.6b, —N(R.sup.6a)C(O)—R.sup.6b or —NR.sup.6aR.sup.6b, where any aryl, aryl(1-2C)alkyl, heteroaryl and heteroaryl(1-2C)alkyl in R.sup.6 is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl or (1-4C)alkoxy, and where R.sup.6a and R.sup.6b are independently selected from hydrogen or (1-3C)alkyl, and/or two R.sup.6 located on adjacent atoms are linked to one another, such that when taken in combination with the atoms to which they are attached, they form a monocyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system, wherein any of the said monocyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl or (1-4C)alkoxy; each p is independently selected from 0, 1, 2 or 3; and each R.sup.7 is independently selected from hydrogen or (1-3C)alkyl.

2. The process of claim 1, wherein M.sup.1 is selected from Co, Fe, Cr, Ni, Al, Ti or Zn.

3. The process of claim 1, wherein M.sup.2 is selected from Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Y, Ln, Al, Ga or Sn.

4. The process of claim 1, wherein R.sup.1 has a structure according to Formula A shown below: ##STR00152## wherein W.sup.1, W.sup.2, W.sup.3, W.sup.4 and W.sup.5 are each independently selected from absent, —CH.sub.2—, —NH— or —O—, with the provisos that: i) no more than 3 of W.sup.1, W.sup.2, W.sup.3, W.sup.4 and W.sup.5 are absent, ii) at least 2 of W.sup.1, W.sup.2, W.sup.3, W.sup.4 and W.sup.5 are —CH.sub.2—, and iii) —NH— is not adjacent —O—; and any —CH.sub.2— is optionally substituted with one or two R.sup.x, and any —NH— is optionally substituted with one R.sup.x; each R.sup.x is independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl, (1-4C)alkoxy, phenyl, 5-6 membered heteroaryl or —NR.sup.xaR.sup.xb, where any phenyl or 5-6 membered heteroaryl in R.sup.x is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl ad or (1-4C)alkoxy, and where R.sup.xa and R.sup.xb are independently selected from hydrogen or (1-3C)alkyl, and/or two or more R.sup.x located on adjacent atoms are linked to one another, such that when taken in combination with the atoms to which they are attached, they form a 5-7 membered monocyclic or 8-10 membered bicyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system, wherein any of the said 5-7 membered monocyclic or 8-10 membered bicyclic aromatic, heteroaromatic, carbocyclic or heterocyclic ring system is optionally substituted with one or more groups independently selected from halo, hydroxy, cyano, nitro, (1-4C)alkyl, (1-4C)haloalkyl ad or (1-4C)alkoxy.

5. The process of claim 1, wherein R.sup.1 has a structure according to any one of the following: ##STR00153##

6. The process of claim 1, wherein each R.sup.2 is independently selected from absent, hydrogen, (1-3C)alkyl, phenyl, benzyl and —C(O)—NR.sup.2aR.sup.2b, where any phenyl or benzyl in R.sup.2 is optionally substituted with one or more groups independently selected from halo, hydroxy, (1-2C)alkyl, (1-2C)haloalkyl or (1-2C)alkoxy, and where R.sup.2a and R.sup.2b are independently selected from hydrogen (1-2C)alkyl.

7. The process of claim 1, wherein each X.sup.1 is independently selected from —CH—, —CR.sup.4—, —CH.sub.2—, —CHR.sup.4— or —CR.sup.4R.sup.4—, where each R.sup.4 is independently selected from (1-2C)alkyl ad or phenyl, where any phenyl in R.sup.4 is optionally substituted with one or more groups independently selected from halo, hydroxy, (1-2C)alkyl, (1-2C)haloalkyl or (1-2C)alkoxy.

8. The process of claim 1, wherein E.sup.1 is C and E.sup.2 is O, and wherein G.sup.1 and G.sup.2 are absent.

9. The process of claim 1, wherein each R.sup.3 is independently selected from halo, hydroxy, cyano, nitro, (1-2C)alkyl, (1-2C)haloalkyl, (1-2C)alkoxy, phenyl ad or —NR.sup.3aR.sup.3b, where any phenyl in R.sup.3 is optionally substituted with one or more groups independently selected from halo, hydroxy, (1-2C)alkyl, (1-2C)haloalkyl or (1-2C)alkoxy, and where R.sup.3a and R.sup.3b are independently selected from hydrogen or (1-3C)alkyl; and each n is independently selected from 0, 1 or 2.

10. The process of claim 1, wherein L.sup.1 and L.sup.2 are independently selected from absent or —O—C(O)—R.sup.a, where R.sup.a is (1-20C)alkyl (e.g. acetate, i.e. “OAc”, or stearate) or (2-25C)alkenyl (e.g. oleate).

11. (canceled)

12. The process of claim 1, wherein each X.sup.2 is independently absent or methylene, where said methylene is optionally substituted with 1 or 2 groups independently selected from (1-2C)alkyl; each X.sup.3 is independently absent or (1-2C)alkylene, where said (1-2C)alkylene is optionally substituted with 1 or 2 groups independently selected from (1-2C)alkyl; and each X.sup.4 is independently methylene that is optionally substituted with 1 or 2 methyl groups.

13. (canceled)

14. The process of claim 1, wherein each R.sup.5 is independently selected from hydrogen, halo, hydroxy, (1-3C)alkyl, (1-3C)haloalkyl, (1-3C)alkoxy, phenyl, phenyl(1-2C)alkyl or —NR.sup.5aR.sup.5b, where any phenyl and phenyl(1-2C)alkyl in R.sup.5 is optionally substituted with one or more groups independently selected from halo, hydroxy, (1-2C)alkyl, (1-2C)haloalkyl or (1-2C)alkoxy, and where R.sup.5a and R.sup.5b are independently selected from hydrogen or (1-2C)alkyl, and/or two R.sup.5 located on adjacent atoms are linked to one another, such that when taken in combination with the atoms to which they are attached, they form a benzene or 5-6 membered heteroaromatic ring, wherein any of the said benzene and 5-6 membered heteroaromatic rings is optionally substituted with one or more groups independently selected from halo, hydroxy, (1-2C)alkyl, (1-2C)haloalkyl or (1-2C)alkoxy.

15. The process of claim 1, wherein each R.sup.6 is independently selected from halo, hydroxy, cyano, nitro, (1-2C)alkyl, (1-2C)haloalkyl, (1-2C)alkoxy, phenyl or —NR.sup.6aR.sup.6b, where any phenyl in R.sup.6 is optionally substituted with one or more groups independently selected from halo, hydroxy, (1-2C)alkyl, (1-2C)haloalkyl or (1-2C)alkoxy, and where R.sup.6a and R.sup.6b are independently selected from hydrogen or (1-3C)alkyl; and each p is independently selected from 0 or 1.

16. (canceled)

17. The process of claim 1, wherein Q is Q-I.

18. The process of claim 1, wherein Q has a structure according to any of the following: ##STR00154## ##STR00155##

19. The process of claim 1, wherein the compound of Formula I has a structure according to any of the following:

20. The process of claim 1, wherein the epoxide is selected from ethylene oxide, propylene oxide, vinyl-propylene oxide, butylene oxide, allyl glycidyl ether, tert-butyl glycidyl ether, epichlorohydrin, styrene oxide, cyclohexene oxide, vinyl-cyclohexene oxide, cyclopentene oxide, limonene oxide or mixtures of two or more thereof.

21. The process of claim 1, wherein the epoxide is propylene oxide or cyclohexene oxide.

22. The process of claim 1, wherein step a) is conducted in the presence of a chain transfer agent.

23-24. (canceled)

25. A compound having a structure according to Formula I as defined in claim 1.

Description

EXAMPLES

[0687] One or more examples of the invention will now be described, for the purpose of illustration only, with reference to the accompanying figures, in which:

[0688] FIG. 1 shows the Oak Ridge Thermal Ellipsoid plot (ORTEP) representation of the molecular structure of Complex 1, with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

[0689] FIG. 2 shows ORTEP representation of the molecular structure of Complex 2, with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

[0690] FIG. 3 shows ORTEP representation for the molecular structure of Complex 7 (top) and Complex 7-(EtOH) (bottom) with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

[0691] FIG. 4 shows ORTEP representation for the molecular structure of Complex 12 with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability. The two molecules of Complex 12 are shown coordinated to one another via acetate co-ligands.

[0692] FIG. 5 shows ORTEP representation for the molecular structure of Complex 10 with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

[0693] FIG. 6 shows polymerization data for complex 2: a) Plot of PPC molar mass (Mn: .square-solid.) and dispersity (Ð: .box-tangle-solidup.) versus turnover number (TON). b) Evolution of the PPC molar masses showing an increase in molar mass (g mol.sup.−1) with turnover number (TON) (note the low molar mass shoulder present in some cases arises from chains initiated from catalyst acetate groups). c) MALDI-ToF spectrum (1000-6000 m/z) of PPC initiated from acetate (.circle-solid.) and cyclohexane diol+one ether linkage (.square-solid.). d) Expanded region of the MALDI-ToF spectrum (4000-5000 m/z) showing both polymer distributions having a repeat unit of 102 g mol.sup.−1 consistent with the value expected for PPC.

[0694] FIG. 7 shows Kinetic data and pathway for complex 2: a) Semilogarithmic plot of ln[PO].sub.t/[PO].sub.0 versus time (Table 1, Entry 4). b) Plot of ln[k.sub.obs] vslIn[2], where [2]=1.56-7.13 mM. c) Plot of k.sub.obs vs P.sub.CO2 from 5 to 30 bar. d) Illustration of polymerization pathway and rate-determining step. All errors are calculated from duplicate runs and there is an average error of ±5% on all data.

[0695] FIG. 8 shows, for complex 1, plots used to analyse the polymerization kinetics and determine the reaction orders in various monomers. a) Semilogarithmic plot of cyclohexene oxide concentration vs. time with a linear fit to data indicative of a first order dependence on cyclohexene oxide concentration. b) Plot of activity (TOF) vs. pressure of carbon dioxide, over the range 10-40 bar with a constant value consistent with zero order in CO.sub.2 pressure. c) Logarithmic plot of pseudo first order rate coefficient, k.sub.obs vs. concentration of 7 and the linear fit to the data, used to determine a first order dependence on catalyst concentration d) order in Catalyst.

[0696] FIG. 9 shows a representation for the molecular structure of complex 17 with disorder and hydrogen atoms omitted for clarity.

[0697] FIG. 10 shows an infrared spectrum for complex 27.

[0698] FIG. 11 shows an infrared spectrum for complex 28.

[0699] FIG. 12 shows an infrared spectrum for complex 29.

[0700] FIG. 13 shows ORTEP representation for the molecular structure of Complex 30 with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

MATERIALS

[0701] Solvents and reagents were obtained from commercial sources and used as received unless stated otherwise. Acetonitrile was obtained from a solvent purification system, degassed by several freeze-pump-thaw cycles and further dried with 3 A molecular sieves and stored under N.sub.2. All epoxide monomers were dried over calcium hydride, fractionally distilled, degassed by bubbling N.sub.2 gas and stored under N.sub.2. Research-grade CO.sub.2 was used for polymerization studies.

Methods

General Synthesis of the Pro-Ligand

[0702] The pro-ligand shown below was synthesized following a modified literature procedure.sup.18:

##STR00116##

General Synthesis of the Catalytic Compounds

[0703] General synthesis of catalysts by diamine condensation and metal complexation was carried out in a one-pot procedure: M.sup.2(OAc).sub.x (where M.sup.2 is Na, Mg, K, Rb or Cs and x is 1, 2 or 3 as appropriate) (1.03 mmol) was added to solution of pro-ligand (1.03 mmol) in acetonitrile (15 mL) and stirred for 30 mins at 25° C. under N.sub.2. M.sup.1(OAc).sub.x (where M.sup.1 is Co, Zn, Mg or Ni and x is 1, 2 or 3 as appropriate) (1.03 mmol) was added to the reaction mixture and stirred for a further 2 h at 25° C. under N.sub.2. A diamine (shown below) (1.03 mmol) was added drop-wise to the reaction mixture and was stirred for 16 h at 25° C. under N.sub.2.

##STR00117##

The resulting complexes were oxidized by exposure to air and the addition of acetic acid (1.03 mmol) and was stirred for up to 72 h (followed by .sup.1H NMR spectroscopy). The solution was filtered and solvent volume reduced in vacuo. Excess acetic acid was removed by azeotropic evacuation with toluene (3×25 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo affording a solid.

[0704] The complexes were characterized by NMR spectroscopy, mass spectrometry, IR spectroscopy and single crystal X-ray diffraction, with purity determined by elemental analysis.

Characterisation

[0705] For .sup.1H NMR, solution state .sup.13C{.sup.1H} NMR and all 2D NMR, a Bruker Avance Ill HD nanobay NMR equipped with a 9.4 T magnet (.sup.1H 400 MHz, .sup.13C 100 MHz) NMR spectrometer was used. For all solid state .sup.13C{.sup.1H} NMR, a Bruker Avance Ill HD Solid state NMR equipped with a 9.4 T magnet (.sup.1H 400 MHz, .sup.13C 100 MHz) was used.

[0706] MALDI-ToF analysis was performed on a Micromass MALDI micro MX spectrometer. The matrix used in combination with complexes was trans-1-[3-(4-tertbutylphenyl)-2-methyl-2-propenyldene]-malonitrile. The matrix used in combination with polymers was dithranol.

[0707] Crystalline samples were isolated and mounted on a MiTeGen MircoMounts. The crystal is cooled to 150 K, with Oxford Cryosystems nitrogen cooling device. Data is collected using an Oxford Diffraction Supernova diffractometer using Cu Kα (λ=1.5417 Å) radiation. The resulting raw data was processed using CrysAlisPro. Structures were solved by SHELXT and full-matrix least squares refinements based on F2 were performed in SHELXL-14, as incorporated in the WinGX package.

[0708] Elemental analysis determined by Mr Eric Coleman at London Metropolitan University.

[0709] Gel permeation chromatography (GPC) analysis was conducted using a Shimadzu LC-20AD instrument, at 40° C., with two mixed bed PSS SDV linear S columns in series, and with THF as eluent at a flow rate of 1 mL/min.

General Procedure for Copolymerisation Reactions

[0710] A solution of catalyst and cyclohexene diol in epoxide (3-15 mL) was injected into a 100 mL Parr reactor fitted with a DiComp sentinel probe for insitu-IR spectroscopic measurements. The reactor vessel was then pressurized with CO.sub.2 to the targeted reaction pressure and allowed to reach the required temperature.

Example 1—Catalyst Synthesis

Synthesis of Complex 1

[0711] ##STR00118##

[0712] Complex 1 was synthesised by addition of sodium acetate, along with cobalt acetate, to the pro-ligand in acetonitrile at 25° C. under N.sub.2 and stirred for 30 min. This was followed by the addition of ethylene diamine, under a N.sub.2 atmosphere at 25° C. and stirred for 16 h. The resulting solution was exposed to air and oxidized by adding an additional equivalence of acetic acid. The resulting suspension was filtered, with excess acetic acid removed through azeotropic evaporation with toluene, followed by pentane washes resulting in a pale brown solid.

[0713] Complex 1: (0.37 g, 0.61 mmol, 59%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 7.76 (2H, s, HC═N) 6.88 (2H, d, meta-ArH) 6.79 (2H, d, meta-ArH) 6.44 (2H, t, para-ArH) 4.35 (4H, s, CH.sub.2N═CH) 4.20-3.94 (16H, s, O—CH.sub.2—) 1.44 (6H, s, CH.sub.3COO). .sup.13C{1H} NMR (125 MHz, CDCl.sub.3, 298 K) δ (ppm): 179.5 (H.sub.3CCOO) 164.7 (HC═N) 157.0 (ipso-Ar) 152.0 (ortho-Ar) 126.5 (meta-Ar) 119.4 (ortho-Ar) 112.7 (meta-Ar) 112.4 (para-Ar) 69.1, 69.1, 67.2 (OCH2-) 58.9 (CH.sub.2—N═CH) 24.2 (H.sub.3CCOO). HRMS (ESI/FTMS) m/z: [7−OAc].sup.+ Calcd for C.sub.24H.sub.27CoN.sub.2NaO.sub.8 553.0992; Found 553.0977. Anal. Calcd for C.sub.26H.sub.30CoNaN.sub.2O.sub.10: Calculated; C, 51.0; H, 4.9; N, 4.6%. Found: C, 50.7; H, 4.8; N, 4.4.

[0714] FIG. 1 shows the ORTEP representation of the molecular structure of complex 1, with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

Synthesis of Complex 2

[0715] ##STR00119##

[0716] Complex 2 was synthesised by addition of potassium acetate, along with cobalt acetate, to the pro-ligand in acetonitrile at 25° C. under N.sub.2 and stirred for 30 min. This was followed by the addition of ethylene diamine, under a N.sub.2 atmosphere at 25° C. and stirred for 16 h. The resulting solution was exposed to air and oxidized by adding an additional equivalence of acetic acid. The resulting suspension was filtered, with excess acetic acid removed through azeotropic evaporation with toluene, followed by pentane washes resulting in a pale brown solid.

[0717] Complex 2: (0.92 g, 1.47 mmol, 74%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 7.70 (2H, s, HC═N) 6.85 (2H, d, meta-ArH) 6.70 (2H, d, meta-ArH) 6.40 (2H, t, para-ArH) 4.31 (4H, s, CH.sub.2N═CH) 4.18-3.80 (16H, s, O—CH.sub.2—) 1.45 (6H, s, CH.sub.3COO). .sup.13C{1H} NMR (125 MHz, CDCl.sub.3, 298 K) δ (ppm): 179.5 (H.sub.3CCOO) 164.8 (HC═N) 157.1 (ip-so-Ar) 152.1 (ortho-Ar) 126.1 (meta-Ar) 119.0 (ortho-Ar) 112.6 (meta-Ar) 112.4 (para-Ar) 70.2, 69.6, 66.1 (OCH.sub.2—) 59.4 (CH.sub.2—N═CH) 24.8 (H.sub.3CCOO). Molecular Cation (MALDI-ToF): 510.5 amu, [LCo(II)K].sup.+. Anal. Calcd for C.sub.26H.sub.30CoKN.sub.2O.sub.10 (628.6 g mol.sup.−1); C, 49.7; H, 4.8; N, 4.5%. Found; C, 49.4; H, 4.7; N, 4.6%.

[0718] FIG. 2 shows the ORTEP representation of the molecular structure of complex 2, with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

Synthesis of Complex 3

[0719] ##STR00120##

[0720] Complex 3 was synthesised by addition of rubidium acetate, along with cobalt acetate, to the pro-ligand in acetonitrile at 25° C. under N.sub.2 and stirred for 30 min. This was followed by the addition of ethylene diamine, under a N.sub.2 atmosphere at 25° C. and stirred for 16 h. The resulting solution was exposed to air and oxidized by adding an additional equivalence of acetic acid. The resulting suspension was filtered, with excess acetic acid removed through azeotropic evaporation with toluene, followed by pentane washes resulting in a pale brown solid.

[0721] Complex 3: (0.38 g, 0.56 mmol, 54%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 7.70 (2H, s, HC═N) 6.86 (2H, d, meta-ArH) 6.73 (2H, d, meta-ArH) 6.42 (2H, t, para-ArH) 4.42 (4H, s, CH.sub.2N═CH) 4.19-3.84 (16H, s, O—CH.sub.2—) 1.45 (6H, s, CH.sub.3COO). .sup.13C{1H} NMR (125 MHz, CDCl.sub.3, 298 K) δ (ppm): 180.1 (H.sub.3CCOO) 165.4 (HC═N) 156.4 (ip-so-Ar) 151.9 (ortho-Ar) 126.2 (meta-Ar) 118.8 (ortho-Ar) 112.8 (meta-Ar) 112.6 (para-Ar) 69.8, 69.4, 66.4 (OCH.sub.2—) 59.3 (CH.sub.2—N═CH) 24.3 (H.sub.3CCOO). Molecular Cation (MALDI-ToF): 556.0 amu, [LCo(II)Rb].sup.+. Anal. Calcd for C.sub.26H.sub.30CoRbN.sub.2O.sub.10 (674.9 g mol.sup.1); C, 46.4; H, 4.5; N, 4.2%. Found; C, 46.3; H, 4.4; N, 4.0%.

Synthesis of Complex 4

[0722] ##STR00121##

[0723] Complex 4 was synthesised by addition of caesium acetate, along with cobalt acetate, to the pro-ligand in acetonitrile at 25° C. under N.sub.2 and stirred for 30 min. This was followed by the addition of ethylene diamine, under a N.sub.2 atmosphere at 25° C. and stirred for 16 h. The resulting solution was exposed to air and oxidized by adding an additional equivalence of acetic acid. The resulting suspension was filtered, with excess acetic acid removed through azeotropic evaporation with toluene, followed by pentane washes resulting in a pale brown solid.

[0724] Complex 4: (0.28 g, 0.39 mmol, 51%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 7.73 (2H, s, HC═N) 6.89 (2H, d, meta-ArH) 6.74 (2H, d, meta-ArH) 6.45 (2H, t, para-ArH) 4.51 (4H, s, CH.sub.2N═CH) 4.15-3.84 (16H, s, O—CH.sub.2—) 1.46 (6H, s, CH.sub.3COO). .sup.13C{1H} NMR (125 MHz, CDCl.sub.3, 298 K) δ (ppm): 179.6 (H.sub.3CCOO) 166.0 (HC═N) 155.4 (ipso-Ar) 151.2 (ortho-Ar) 126.5 (meta-Ar) 119.4 (ortho-Ar) 112.9 (meta-Ar) 112.8 (para-Ar) 69.2, 68.9, 66.5 (OCH.sub.2—) 59.9 (CH.sub.2—N═CH) 24.7 (H.sub.3CCOO). Molecular Cation (MALDI-ToF): 604.4 amu, [LCo(II)Cs].sup.+. Anal. Calcd for C.sub.26H.sub.30CoCsN.sub.2O.sub.10 (722.37 g mol.sup.−1); C, 43.2; H, 4.2; N, 3.9%. Found; C, 43.5; H, 4.0; N, 4.0%.

Synthesis of Complex 5

[0725] ##STR00122##

[0726] Complex 5 was synthesised by addition of the pro-ligand and sodium acetate to methanol. A solution of ethylene diamine in methanol was added dropwise over the course of 3 h. The solution was left to cool to room temperature, before Zn(OAc).sub.2.Math.2(H.sub.2O) was added and left to stir for 1 h. The solvent was removed under reduced pressure to obtain a pale yellow glassy solid as the crude product. This was triturated with dichloromethane and dried under vacuum at 60° C. to give a pure product.

[0727] Complex 5: (298 mg, 0.53 mmol, 69%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 8.29 (2H, s, —HC═N—), 6.81 (4H, m, Ar—H.sub.meta), 6.41 (2H, m, Ar—H.sub.para), 4.22-3.60 (16H, m, —O—CH.sub.2—, ═N—CH.sub.2—), 1.81 (3H, s, H.sub.3C—C(O)O). .sup.13C NMR (100 MHz, CDCl.sub.3, 298 K) δ (ppm): 177.0 (—C(O)O), 167.6 (—HC═N—), 150.8 (Ar—C.sub.ortho—O—CH.sub.2), 128.0 (Ar—C.sub.meta), 120.0 (Ar—C.sub.ipso), 117.7 (Ar—C.sub.meta), 112.0 (Ar—C.sub.para), 70.1 (—O—CH.sub.2—), 69.8 (—O—CH.sub.2—), 67.8 (—O—CH.sub.2—), 56.1 (═N—CH.sub.2—), 23.6 (H.sub.3C—C(O)O). Anal. Calcd for C.sub.28H.sub.27N.sub.2NaO.sub.8Zn: C, 51.49; H, 4.86; N, 5.00. Found: C, 51.80; H, 4.97; N, 5.22.

Synthesis of Complex 6

[0728] ##STR00123##

[0729] Complex 6 was synthesised by addition of the pro-ligand and sodium acetate to methanol. A solution of ethylene diamine in methanol was added dropwise over the course of 3 h. The solution was left to cool to room temperature, before Mg(OAc).sub.2.Math.4(H.sub.2O) was added and left to stir for 1 h. The solvent was removed under reduced pressure to obtain a pale yellow glassy solid as the crude product. The product was recrystallized from methanol/diethyl ether mixture (1:10) at −20° C. The crystals were washed with pentane and triturated with chloroform and dried under vacuum at 40° C. to obtain the pure product.

[0730] Complex 6: (59.1 mg, 0.11 mmol, 15%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 8.20 (2H, s, —HC═N—), 6.79 (4H, m, Ar—H.sub.meta), 6.33 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.7 Hz), 4.38-3.42 (16H, m, —O—CH.sub.2—, ═N—CH.sub.2—), 1.75 (3H, s, H.sub.3C—C(O)O). .sup.13C NMR (100 MHz, CDCl.sub.3, 298 K) δ (ppm): 179.2 (—C(O)O), 167.8 (—HC═N—), 161.0 (Ar—C.sub.ortho—HC═N—), 150.6 (Ar—C.sub.ortho—O—CH.sub.2), 128.3 (Ar—C.sub.meta), 121.7 (Ar—C.sub.ipso), 118.5 (Ar—C.sub.meta), 111.8 (Ar-C.sub.para), 70.6 (—O—CH.sub.2—), 69.9 (—O—CH.sub.2—), 67.9 (—O—CH.sub.2—), 57.2 (═N—CH.sub.2—), 24.2 (H.sub.3C—C(O)O).

Synthesis of Complex 7

[0731] ##STR00124##

[0732] Complex 7 was synthesised by addition of the pro-ligand and sodium acetate to methanol. A solution of 2,2-dimethylpropane-1,3-diamine in methanol was added dropwise over the course of 3 h. The solution was left to cool to room temperature, before Zn(OAc).sub.2.Math.2(H.sub.2O) was added and left to stir for 1 h. The solvent was removed under reduced pressure to obtain a pale yellow glassy solid as the crude product. This was triturated with ethanol and dichloromethane and dried under vacuum at 40° C. to give a pure product.

[0733] Complex 7: (343 mg, 0.57 mmol, 74%).sup.1H NMR (400 MHz, C.sub.2D.sub.2Cl.sub.4, 298 K) δ (ppm): 7.87 (s, 2H, —HC═N—), 6.85 (dd, 2H, Ar—H.sub.meta, .sup.3J.sub.H-H=7.6 Hz, .sup.4J.sub.H-H=1.8 Hz), 6.81 (dd, 2H, Ar—H.sub.meta, .sup.3J.sub.H-H=7.6 Hz, .sup.4J.sub.H-H=1.8 Hz), 6.42 (t, 2H, Ar—H.sub.para, .sup.3J.sub.H-H=7.7 Hz), 4.26-3.64 (m, 14H, —H.sub.2C—N═, —O—CH.sub.2—), 3.09 (d, 2H, —H.sub.2C—N═, .sup.3J.sub.H-H=12.0 Hz), 1.89 (s, 3H, H.sub.3C—C(O)O), 1.08 (s, 3H, H.sub.3C—C—), 0.82 (s, 3H, H.sub.3C—C—). .sup.13C NMR (100 MHz, C.sub.2D.sub.2Cl.sub.4, 298 K) δ (ppm): 177.5 (—C(O)O), 168.6 (—HC═N—), 162.1 (Ar—C.sub.ortho), 150.5 (Ar—C.sub.ortho), 128.3 (Ar—C.sub.meta), 119.06 (Ar—C.sub.meta), 117.46 (Ar—C.sub.ipso), 111.6 (Ar-C.sub.para), 74.65 (—H.sub.2C—N═), 68.93 (—H.sub.2C—N═, —O—CH.sub.2—), 68.48 (—H.sub.2C—N═, —O—CH.sub.2—), 68.40 (—H.sub.2C—N═, —O—CH.sub.2—), 36.13 ((H.sub.3C).sub.2—C—), 27.28 (H.sub.3C—C—), 24.73 (H.sub.3C—C(O)O), 22.29 (H.sub.3C—C—). Anal calcd (found) for C.sub.27H.sub.33N.sub.2NaO.sub.3Zn: C, 53.88 (53.81); H, 5.53 (5.62); N 4.65 (4.60).

[0734] FIG. 3 shows ORTEP representation for the molecular structure of complex 7 with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

Synthesis of Complex 8

[0735] ##STR00125##

[0736] Complex 8 was synthesised by addition of the pro-ligand and sodium acetate to methanol. A solution of 2,2-dimethylpropane-1,3-diamine in methanol was added dropwise over the course of 3 h. The solution was left to cool to room temperature, before Ni(OAc).sub.2.Math.4(H.sub.2O) was added and left to stir for 1 h. The solvent was removed under reduced pressure to obtain a pale yellow glassy solid as the crude product. This was triturated with ethanol and dichloromethane and dried under vacuum at 40° C. to give a pure product.

[0737] Complex 8: (262 mg, 0.45 mmol, 58%)

Synthesis of Complex 9

[0738] ##STR00126##

[0739] Complex 9 was synthesised by addition of the pro-ligand and sodium acetate to methanol. A solution of 2,2-dimethylpropane-1,3-diamine in methanol was added dropwise over the course of 3 h. The solution was left to cool to room temperature before Mg(OAc).sub.2.Math.4(H.sub.2O) was added and left to stir for 1 h. The solvent was removed under reduced pressure to obtain a pale yellow glassy solid as the crude product. This was triturated with ethanol and dichloromethane and dried under vacuum at 40° C. to give a pure product.

[0740] Complex 9: (179 mg, 0.32 mmol, 63%).sup.1H NMR (400 MHz, C.sub.2D.sub.2Cl.sub.4, 398 K) δ (ppm): 8.05 (s, 2H, —HC═N—), 6.88 (m, 4H, Ar—H.sub.meta), 6.46 (t, 2H, Ar—H.sub.para, .sup.3J.sub.H-H=7.5 Hz), 4.25-3.61 (m, 16H, —H.sub.2C—N═, —O—CH.sub.2—), 1.99 (s, 6H, H.sub.3C—C(O)O), 1.01 (s, 6H, H.sub.3C—C—). Anal calcd (found) for C.sub.27H.sub.33MgN.sub.2NaO.sub.8: C, 57.82 (55.15); H, 5.93 (6.21); N 4.99 (4.40).

Synthesis of Complex 10

[0741] ##STR00127##

[0742] Complex 10 was synthesised by addition of the pro-ligand and sodium acetate to methanol under N.sub.2. A solution of 2,2-dimethylpropane-1,3-diamine in methanol was added dropwise over the course of 3 h under an atmosphere of N.sub.2. The solution was left to cool to room temperature before Co(OAc).sub.2.Math.4(H.sub.2O) (256 mg, 1.03 mmol) was added and the solution left to stir overnight. The mixture was further stirred under ambient conditions for 24 h. The solvent was removed under reduced pressure to obtain a dark brown glassy solid. This was dissolved in acetonitrile and diluted with diethyl ether. The precipitate was isolated by filtration and triturated once with chloroform to obtain the product.

[0743] Complex 10: (533 mg, 0.81 mmol, 79%).sup.1H NMR (400 MHz, C.sub.2D.sub.2Cl.sub.2, 298 K) δ (ppm): 7.24 (s, 2H, —HC═N—), 6.82 (dt, 2H, Ar—H.sub.meta, .sup.3J.sub.H-H=21.4, .sup.4J.sub.H-H=5.3 Hz), 6.55-6.44 (mm, 2H, Ar—H.sub.meta), 4.30-3.69 (m, 12H, —O—CH.sub.2—), 3.41 (s, 4H, —H.sub.2C—N═), 1.47 (s, 6H, H.sub.3C—C(O)O), 1.19 (S, 6H, H.sub.3C—C—). .sup.13C NMR (100 MHz, C.sub.2D.sub.2Cl.sub.2, 298 K) δ (ppm): 180.8 (—C(O)O), 166.2 (—HC═N—), 157.1 (Ar—C.sub.ortho), 151.9 (Ar—C.sub.ortho), 126.3 (Ar—C.sub.meta), 122.6 (Ar—C.sub.ipso), 117.25 (Ar—C.sub.meta), 114.2 (Ar-C.sub.para), 71.22 (═N—CH.sub.2—), 68.77 (—O—CH.sub.2—), 68.08 (—O—CH.sub.2—), 35.07 ((H.sub.3C).sub.2—C—(CH.sub.2).sub.2), 25.13 (H.sub.3C—C(O)O, H.sub.3C—C—), 24.62 (H.sub.3C—C(O)O), H.sub.3C—C—). Anal calcd (found) for C.sub.27H.sub.33CoN.sub.2NaO.sub.3: C, 54.46 (53.57); H, 5.59 (5.38); N 4.70 (4.73).

[0744] FIG. 5 shows ORTEP representation for the molecular structure of complex 10 with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

Synthesis of Complex 11

[0745] ##STR00128##

[0746] Complex 11 was synthesised by addition of the pro-ligand and Mg(OAc).sub.2.Math.4(H.sub.2O) to methanol. A solution of 2,2-dimethylpropane-1,3-diamine in methanol was added dropwise over the course of 3 h. The solution was left to cool to room temperature, before the Zn(OAc).sub.2.Math.2(H.sub.2O) was added and left to stir for 1 h. The solvent was removed under reduced pressure to obtain a pale yellow glassy solid as the crude. This was triturated with ethanol and dichloromethane and dried under vacuum at 40° C. to give a pure product.

[0747] Complex 11: (359 mg, 0.554 mmol, 72%).sup.1H NMR (400 MHz, C.sub.2D.sub.2Cl.sub.4, 328 K) δ (ppm): 8.00 (s, 2H, —HC═N—), 6.80 (dd, 4H, Ar—H.sub.meta, .sup.3J.sub.H-H=18.5 Hz, .sup.4J.sub.H-H=7.8 Hz), 6.59 (t, 2H, Ar—H.sub.para, .sup.3J.sub.H-H=7.9 Hz), 4.32 (d, 2H, —H.sub.2C—N═, .sup.2J.sub.H-H=11.9 Hz), 4.21 (s, 4H, —O—CH.sub.2—), 3.98-3.60 (m, 8H, —O—CH.sub.2—), 3.13 (d, 2H, —H.sub.2C—N═, .sup.2J.sub.H-H=11.9 Hz), 2.00 (s, 6H, H.sub.3C—C(O)O), 1.13 (s, 3H, H.sub.3C—C—), 0.85 (s, 3H, H.sub.3C—C—). .sup.13C NMR (100 MHz, C.sub.2D.sub.2Cl.sub.4, 328 K). δ (ppm): 168.2 (—HC═N—), 157.9 (Ar—C.sub.ortho), 148.9 (Ar—C.sub.ortho), 126.5 (Ar—C.sub.meta), 118.3 (Ar—C.sub.ipso), 113.4 (Ar-C.sub.para), 112.4 (Ar—C.sub.meta), 74.42 (—H.sub.2C—N═), 69.36 (—O—CH.sub.2—), 68.10 (—O—CH.sub.2—), 66.66 (—O—CH.sub.2—), 57.90 (—O—CH.sub.2—), 35.56 ((H.sub.3C).sub.2—C—), 26.69 (H.sub.3C—C—), 21.51 (H.sub.3C—C—, H.sub.3C—C(O)O). Anal calcd (found) for C.sub.29H.sub.36MgN.sub.2O.sub.10Zn: C, 52.59 (52.48); H, 5.48 (5.29); N 4.23 (4.25).

Synthesis of Complex 12

[0748] ##STR00129##

[0749] Complex 12 was synthesised by addition of the pro-ligand and sodium acetate to methanol. A solution of O-phenylenediamine in methanol was added dropwise over the course of 3 h. The solution was left to cool to room temperature, before Zn(OAc).sub.2.Math.2(H.sub.2O) was added and left to stir for 1 h. The solvent was removed under reduced pressure leaving a yellow-orange powder contaminated by acetic acid. The solid crude was triturated with methanol and washed with diethyl ether to remove the acid by-product to give the target compound.

[0750] Complex 12: (0.53 mmol, 320 mg, 68%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 8.68 (2H, s, —HC═N—), 7.57 (2H, m, Ar—H.sub.ortho′), 7.31 (2H, m, Ar—H.sub.meta′), 6.96 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=8.02 Hz, .sup.4J.sub.H-H=1.69 Hz), 6.90 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=7.60 Hz, .sup.4J.sub.H-H=1.73 Hz), 6.46 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.75 Hz), 4.34-3.76 (12H, m, —O—CH.sub.2—), 1.79 (3H, S, H.sub.3C—C(O)O). .sup.13C{.sup.1H} CP-MAS (100 MHz, 298 K) δ (ppm): 178.0 (—C(O)O), 162.8, 161.5, 159.6, 151.3 (Ar—C.sub.ortho—O—CH.sub.2), 139.3 (Ar—C.sub.ipso), 127.7, 125.5 (Ar—C.sub.meta′, Ar—C.sub.meta), 118.6, 115.7, 110.1 (Ar—C.sub.para, Ar—C.sub.meta, Ar—C.sub.ortho′), 73.3 (—O—CH.sub.2—), 69.3 (—O—CH.sub.2—), 67.5 (—O—CH.sub.2—), 65.8 —O—CH.sub.2—), 24.5 (H.sub.3C—C(O)O). Anal. Calcd for C.sub.28H.sub.27N.sub.2NaO.sub.8Zn: C 55.32; H, 4.48; N, 4.61. Found: C 55.19; H, 4.62; N, 4.49.

[0751] FIG. 4 shows ORTEP representation for the molecular structure of complex 12 with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

Synthesis of Complex 13

[0752] ##STR00130##

[0753] Complex 13 was synthesised by addition of the pro-ligand and sodium acetate to methanol. A solution of 0-phenylenediamine in methanol was added dropwise over the course of 3 h. The solution was left to cool to room temperature, before Mg(OAc).sub.2.Math.4(H.sub.2O) was added and left to stir for 1 h. The solvent was removed under reduced pressure leaving a yellow-orange powder. The solid crude was triturated with methanol and chloroform and washed with diethyl ether, then stirred in excess ethanol overnight. Ethanol was removed under reduced pressure to give pure product.

[0754] Complex 13: (0.25 mmol, 144 mg, 33%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 8.68 (2H, s, —HC═N—), 7.57 (2H, m, Ar—H.sub.ortho′), 7.32 (2H, m, Ar—H.sub.meta′), 6.96 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=8.02 Hz, .sup.4J.sub.H-H=1.69 Hz), 6.91 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=7.60 Hz, .sup.4J.sub.H-H=1.73 Hz), 6.46 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.75 Hz), 4.33-3.76 (12H, m, —O—CH.sub.2—), 1.79 (3H, S, H.sub.3C—C(O)O). .sup.13C{.sup.1H} CP-MAS (100 MHz, 298K) δ (ppm): 177.0 (—C(O)O), 161.5, 160.2 (Ar—C.sub.ortho—HC═N—, HC═N—), 151.2 (Ar—C.sub.ortho—O—CH.sub.2), 141.2 (Ar—C.sub.ipso′), 127.7, 125.6 (Ar—C.sub.ortho′, Ar—C.sub.meta), 120.4 (Ar—C.sub.ipso), 117.9, 115.5, 111.6 (Ar—C.sub.para, Ar—C.sub.meta, Ar—C.sub.meta′), 73.1 (—O—CH.sub.2—), 69.3 (—O—CH.sub.2—), 67.4 (—O—CH.sub.2—), 65.9 (—O—CH.sub.2—), 24.6 (H.sub.3C—C(O)O). Anal. Calcd for C.sub.28H.sub.27N.sub.2NaO.sub.8Mg: C, 59.33; H, 4.80; N, 4.94. Found: C, 59.14; H, 4.76; N, 4.83.

Synthesis of Complex 14

[0755] ##STR00131##

[0756] Complex 14 was synthesised by addition of the pro-ligand and sodium acetate to methanol under N.sub.2. A solution of 0-phenylenediamine in methanol was added dropwise over the course of 3 h under an atmosphere of N.sub.2. The solution was left to cool to room temperature before Co(OAc).sub.2 4(H.sub.2O) (256 mg, 1.03 mmol) was added and the solution left to stir overnight.

[0757] The mixture was further stirred under ambient conditions for 24 h. The solvent was removed under reduced pressure to obtain a dark brown glassy powder. This was dissolved in acetonitrile and diluted with diethyl ether, precipitating a black solid which was removed by filtration and triturated once with chloroform obtaining the pure product.

[0758] Complex 14: (291 mg, 0.44 mmol, 43%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 8.23 (2H, s, —HC═N—), 8.00 (2H, m, Ar—H.sub.ortho′), 7.38 (2H, m, Ar—H.sub.meta′), 7.04 (2H, d, Ar—H.sub.meta, .sup.3J.sub.H-H=7.96 Hz), 6.82 (2H, d, Ar—H.sub.meta, .sup.3J.sub.H-H=7.55 Hz), 6.51 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.81 Hz), 4.23 (4H, m, —O—CH.sub.2—), 3.85 (4H, m, —O—CH.sub.2—), 3.65 (4H, s, —O—CH.sub.2—), 1.38 (3H, s, H.sub.3C—C(O)O). .sup.13C{.sup.1H}CP-MAS (100 MHz, 298K) δ (ppm): 181.7 (—C(O)O), 178.1 (—C(O)O), 160.7, 157.5, 151.9 (Ar—C.sub.ortho—O—CH.sub.2), 146.1 (Ar—C.sub.ipso), 128.5, 126.5 (Ar—C.sub.ortho′, Ar—C.sub.meta), 119.1 (Ar—C.sub.ipso), 118.6, 115.9, 113.4 (Ar—C.sub.para, Ar—C.sub.meta′, Ar—C.sub.meta), 80.9 (—O—CH.sub.2—), 70.3 (—O—CH.sub.2—), 68.2 (—O—CH.sub.2—), 66.9 (—O—CH.sub.2—), 25.3 (H.sub.3C—C(O)O), 23.6 (H.sub.3C—C(O)O). Anal. Calcd for C.sub.30H.sub.30N.sub.2NaO.sub.10Zn: C, 54.55; H, 4.58; N, 4.24. Found: C, 54.35; H, 4.44; N, 4.14. HRMS (ESI/FTMS) m/z: [10−OAc].sup.+ Calcd for C.sub.28H.sub.27CoN.sub.2NaO.sub.8 601.0992; Found 601.0980.

Synthesis of Complex 15

[0759] ##STR00132##

[0760] Complex 15 was synthesised by addition of the pro-ligand and sodium acetate to methanol. A solution of 2,2-dimethylpropane-1,3-diamine in methanol was added dropwise over the course of 3 h. The solvent was removed under reduced pressure to obtain a pale yellow glassy solid as the crude product. The resultant solid was washed with deionized water, then dissolved in MeOH. 20 equiv. of NaBH.sub.4 was added in one portion and left to stir for 2 h. Water was added to quench the excess NaBH.sub.4 and the solvent was subsequently removed under reduced pressure. The resulting solid was washed with distilled water. The solid was then dissolved in MeOH before Zn(OAc).sub.2.Math.2(H.sub.2O) and sodium acetate was added and left to stir for 1 h. The solvent was removed under reduced pressure to obtain a yellow glassy solid as the crude product. This was triturated with ethanol and dichloromethane and dried under vacuum at 40° C. to give a pure product.

[0761] Complex 15: (256 mg, 0.424 mmol, 65%).sup.1H NMR (500 MHz, C.sub.2D.sub.2Cl.sub.4, 298 K) δ (ppm): 6.79 (2H, d, Ar—H.sub.meta, .sup.3J.sub.H-H=7.9 Hz), 6.67 (2H, d, Ar—H.sub.meta, .sup.3J.sub.H-H=7.4 Hz), 6.50 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.7 Hz), 4.22-3.58 (16H, m, —O—CH.sub.2—, —NH—CH.sub.2—Ar), 3.16 (CH.sub.2—NH—CH.sub.2), 2.75 (2H, t, —NH—CH.sub.2—C(CH.sub.3).sub.2—, .sup.3J.sub.H-H=12.4 Hz), 2.41 (2H, d, —NH—CH.sub.2—C(CH.sub.3).sub.2—, .sup.3J.sub.H-H=11.4 Hz), 1.83 (6H, s, H.sub.3C—C(O)O), 1.23 (3H, s, C—CH.sub.3), 0.90 (3H, s, C—CH.sub.3). .sup.13C NMR (125 MHz, C.sub.2D.sub.2Cl.sub.4, 298 K) δ (ppm): 177.1 (—C(O)O), 154.7 (Ar—C.sub.ortho—O—CH.sub.2), 149.6 (Ar—C.sub.ortho—CH.sub.2), 124.9 (Ar—C.sub.ipso), 123.7 (Ar—C.sub.meta), 114.33 (Ar—C.sub.meta), 113.6 (Ar-C.sub.para), 69.40 (—O—CH.sub.2—), 69.12 (—O—CH.sub.2—), 67.93 (—O—CH.sub.2—), 61.82 ((CH.sub.3).sub.2C—CH.sub.2—NH.sub.2), 54.19 (NH.sub.2—CH.sub.2—Ar), 34.12 (C(CH.sub.3).sub.2), 31.17 (C—CH.sub.3), 22.52 (H.sub.3C—C(O)O, C—CH.sub.3). Anal calcd (found) for C.sub.27H.sub.37N.sub.2NaO.sub.3Zn: C, 53.52 (53.67); H, 6.15 (6.06); N 4.62 (4.68).

Synthesis of Complex 16

[0762] ##STR00133##

[0763] Complex 16 was synthesised by addition of the pro-ligand and sodium acetate to methanol. A solution of 2,2-dimethylpropane-1,3-diamine in methanol was added dropwise over the course of 3 h. The solvent was removed under reduced pressure to obtain a pale yellow glassy solid as the crude product. The resultant solid was washed with deionized water, then dissolved in MeOH. 20 equiv. of NaBH.sub.4 was added in one portion and left to stir for 2 h. Water was added to quench the excess NaBH.sub.4 and the solvent was subsequently removed under reduced pressure. The resulting solid was washed with distilled water. The solid was then dissolved in MeOH before Ni(OAc).sub.2.Math.4(H.sub.2O) and sodium acetate was added and left to stir for 1 h. The solvent was removed under reduced pressure to obtain a yellow glassy solid as the crude product. This was triturated with ethanol and dichloromethane and dried under vacuum at 40° C. to give a pure product.

[0764] Complex 16: (244 mg, 0.41 mmol, 53%)

Synthesis of Complex 17

[0765] ##STR00134##

[0766] Complex 17 was synthesised under a nitrogen atmosphere. The appropriate KOAc (0.769 mmol) was added to solution of the ligand (0.30 g, 0.769 mmol) in acetonitrile (15-40 mL) and the solution was stirred for 30 mins, at 25° C. Next, Co(OAc).sub.2 (0.769 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. 1,2-phenylene diamine (0.769 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C. The complexes were oxidized by exposure to air and by the addition of 1 equivalents of acetic acid (44 μL, 0.769 mmol) and the solution was stirred for up to 72 h with reaction progress being monitored using .sup.1H NMR spectroscopy. Once the oxidation was complete, the suspension was filtered, and residual solvent volume reduced in vacuo. Excess acetic acid was removed by azeotropic distillation with toluene (3×50 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

[0767] Complex 17 (42% yield): .sup.1H NMR (400 MHz, CDCl.sub.3, 298 K). δ (ppm): 8.20 (2H, s, —HC═N—), 8.02 (2H, m, Ar—H.sub.ortho′), 7.38 (2H, m, Ar—H.sub.meta′), 7.01 (2H, d, Ar—H.sub.meta, .sup.3J.sub.H-H=8.60 Hz), 6.82 (2H, d, Ar—H.sub.meta, .sup.3J.sub.H-H=8.60 Hz), 6.47 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.80 Hz), 4.21 (4H, m, —O—CH.sub.2—), 3.98 (4H, m, —O—CH.sub.2—), 3.83 (4H, s, —O—CH.sub.2—), 1.39 (3H, s, H.sub.3C—C(O)O).

[0768] FIG. 9 shows a representation for the molecular structure of complex 17 with disorder and hydrogen atoms omitted for clarity.

Synthesis of Complex 18

[0769] ##STR00135##

[0770] Complex 18 was synthesised under a nitrogen atmosphere. The appropriate KOAc (0.769 mmol) was added to solution of the ligand (0.30 g, 0.769 mmol) in acetonitrile (15-40 mL) and the solution was stirred for 30 mins, at 25° C. Next, Co(OAc).sub.2 (0.769 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. 4,5-dichloro-o-phenylenediamine (0.769 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C.

[0771] The complexes were oxidized by exposure to air and by the addition of 1 equivalents of acetic acid (44 μL, 0.769 mmol) and the solution was stirred for up to 72 h with reaction progress being monitored using .sup.1H NMR spectroscopy. Once the oxidation was complete, the suspension was filtered, and residual solvent volume reduced in vacuo. Excess acetic acid was removed by azeotropic distillation with toluene (3×50 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

[0772] Complex 18 (45% yield): .sup.1H NMR (500 MHz, CDCl.sub.3, 298K). δ (ppm): 8.06 (4H, s, —HC═N—, CIC—HC═C—N—), 6.99 (2H, m, Ar—H.sub.meta), 6.74 (2H, m, Ar—H.sub.meta), 6.48 z (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.8 Hz), 4.24-3.82 (12H, m, —O—CH.sub.2—), 1.39 (6H, s, H.sub.3C—C(O)O). .sup.13C NMR (125 MHz, CDCl.sub.3, 298K). δ (ppm): 179.38 (—C(O)O), 158.90 (—HC═N—), 157.21 (Ar—C.sub.ipso—O—, Ar—C.sub.ortho—O/CH), 151.64 (Ar—C.sub.ipso—O—, Ar—C.sub.ortho—O/CH), 146.15 (Ar—C—C.sub.1, Ar—C—N), 130.67 (Ar—C—C.sub.1, Ar—C—N), 127.04 (Ar—C.sub.meta), 117.78 (Ar—CIC═CH—), 116.36 (Ar—C.sub.ipso—O—, Ar—C.sub.ortho—O/CH), 113.36+113.25 (Ar—C.sub.para, Ar—C.sub.meta), 69.90 (—O—CH.sub.2—), 69.03 (—O—CH.sub.2—), 66.10 (—O—CH.sub.2—), 24.46 (H.sub.3C—C(O)O).

Synthesis of Complex 19

[0773] ##STR00136##

[0774] Complex 19 was synthesised under a nitrogen atmosphere. The appropriate KOAc (0.769 mmol) was added to solution of the ligand (0.30 g, 0.769 mmol) in acetonitrile (15-40 mL) and the solution was stirred for 30 mins, at 25° C. Next, Co(OAc).sub.2 (0.769 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. 1,2-diamine-4,5-difluoro-benzene (0.769 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C. The complexes were oxidized by exposure to air and by the addition of 1 equivalents of acetic acid (44 μL, 0.769 mmol) and the solution was stirred for up to 72 h with reaction progress being monitored using .sup.1H NMR spectroscopy. Once the oxidation was complete, the suspension was filtered, and residual solvent volume reduced in vacuo. Excess acetic acid was removed by azeotropic distillation with toluene (3×50 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

[0775] Complex 19 (9.1% yield): .sup.1H NMR (500 MHz, CDCl.sub.3, 298K). δ (ppm): 7.98 (2H, s, —HC═N—), 7.81 (2H, t, FC—HC═C—N—, .sup.3J.sub.H-F=9.1 Hz), 6.99 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=8.1 Hz, 1.4 Hz), 6.75 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=7.6 Hz, 1.5 Hz), 6.50 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.8 Hz), 4.24-3.82 (12H, m, —O—CH.sub.2—), 1.40 (6H, s, H.sub.3C—C(O)O). .sup.13C NMR (125 MHz, CDCl.sub.3, 298K). δ (ppm): 179.45 (—C(O)O), 158.77 (—HC═N—), 157.18 (Ar—C.sub.ipso—O—, Ar—C.sub.ortho—O/CH), 151.88 (Ar—C.sub.ipso—O—, Ar—C.sub.ortho—O/CH), 143.16 (Ar—C—F, Ar—C—N), 127.27 (Ar—C.sub.meta), 118.13 (Ar—C.sub.ipso—O—, Ar—C.sub.ortho—O/CH), 113.51+113.45 (Ar—C.sub.para, Ar—C.sub.meta), 103.86 (Ar—FC—CH—), 70.14 (—O—CH.sub.2—), 69.38 (—O—CH.sub.2—), 66.33 (—O—CH.sub.2—), 24.85 (H.sub.3C—C(O)O).

Synthesis of Complex 20

[0776] ##STR00137##

[0777] Complex 20 was synthesised under a nitrogen atmosphere. The appropriate KOAc (0.769 mmol) was added to solution of the ligand (0.30 g, 0.769 mmol) in acetonitrile (15-40 mL) and the solution was stirred for 30 mins, at 25° C. Next, Co(OAc).sub.2 (0.769 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. 4,5-dimethyl-1,2-phenylenediamine (0.769 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C. The complexes were oxidized by exposure to air and by the addition of 1 equivalents of acetic acid (44 μL, 0.769 mmol) and the solution was stirred for up to 72 h with reaction progress being monitored using .sup.1H NMR spectroscopy. Once the oxidation was complete, the suspension was filtered, and residual solvent volume reduced in vacuo. Excess acetic acid was removed by azeotropic distillation with toluene (3×50 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

[0778] Complex 20 (52% yield): .sup.1H NMR (400 MHz, d.sup.6-DMSO, 298K). δ(ppm): 8.47 (2H, s, —HC═N—), 8.13 (2H, s, MeC—HC═C—N—), 7.18 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=8.1 Hz, 1.5 Hz), 6.86 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=7.7 Hz, 1.5 Hz), 6.46 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.8 Hz), 4.22-3.80 (12H, m, —O—CH.sub.2—), 2.38 (2H, s, H.sub.3C—C═HC) 1.40 (6H, s, H.sub.3C—C(O)O).

Synthesis of complex 21

[0779] ##STR00138##

[0780] Complex 21 was synthesised by charging a round-bottom flask with LH.sub.2 (300 mg, 0.769 mmol), Ba(ClO.sub.4).sub.2 (258 mg, 0.769 mmol), 4,5-dimethoxybenzene-1,2-diamine (129 mg, 0.769 mmol) and 200 mL of 1:1 MeOH:CHCl.sub.3 and left to stir for 2 hours. The solvent was removed under vacuum and the solid dissolved in 200 mL of CHCl.sub.3. Guanidine sulphate (1.34 g, 12.29 mmol) dissolved in 100 mL of deionised water which was subsequently added to the solution and stirred overnight. The layers were separated, and the product extracted into CHCl.sub.3, which was then dried over magnesium sulphate. The solvent was removed under reduced pressure to give a pale yellow solid (250 mg, 62% yield). A schlenk was charged with the resulting solid (200 mg, 0.383 mmol), Co(OAc).sub.2 (67.8 mg, 0.383 mmol), KOAc (37.6 mg, 0.383 mmol) and acetonitrile (40 mL). This was left to stir for 48 h before being exposed to air and AcOH (33 μL, 0.383 mmol) was added. The mixture was left to stir for a further 48 h before being evaporated to dryness. The solid was triturated with toluene (3×50 mL) and pentane (3×50 mL) and dried under vacuum to give a brown solid.

[0781] Complex 21 (75 mg, 29%): .sup.1H NMR (500 MHz, CDCl.sub.3, 298K). δ (ppm): 8.15 (2H, s, —HC═N—), 7.79 (2H, s, MeOC—HC═C—N—), 7.01 (2H, d, Ar—H.sub.meta, .sup.3J.sub.H-H=8.6 Hz), 6.72 (2H, d, Ar—H.sub.meta, .sup.3J.sub.H-H=8.0 Hz), 6.46 (2H, s, Ar—H.sub.para), 4.24-3.75 (12H, m, —O—CH.sub.2—), 2.40 (6H, s, H.sub.3C—0), 1.39 (6H, s, H.sub.3C—C(O)O).

Synthesis of Complex 22

[0782] ##STR00139##

[0783] Complex 22 was synthesised under a nitrogen atmosphere. The appropriate KOAc (0.769 mmol) was added to solution of the ligand (0.30 g, 0.769 mmol) in acetonitrile (15-40 mL) and the solution was stirred for 30 mins, at 25° C. Next, Co(OAc).sub.2 (0.769 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. (1R,2R)-(−)-1,2-diaminecyclohexane (0.769 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C. The complexes were oxidized by exposure to air and by the addition of 1 equivalents of acetic acid (44 μL, 0.769 mmol) and the solution was stirred for up to 72 h with reaction progress being monitored using .sup.1H NMR spectroscopy. Once the oxidation was complete, the suspension was filtered, and residual solvent volume reduced in vacuo. Excess acetic acid was removed by azeotropic distillation with toluene (3×50 mL). The resulting solid was washed with diethyl ether (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

[0784] Complex 22 (68% yield): .sup.1H NMR (500 MHz, CDCl.sub.3, 298K). δ (ppm): 7.51 (2H, s, —HC═N—), 6.87 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=8.0 Hz, 1.5 Hz), 6.69 (2H, dd, Ar—H.sub.meta, .sup.3J.sub.H-H=7.7 Hz, 1.5 Hz), 6.40 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.8 Hz), 4.24-3.72 (14H, m, —O—CH.sub.2—, —N—CH—), 2.87-2.85 (2H, m, —CH—CH.sub.2—CH.sub.2, —CH.sub.2—CH.sub.2—CH—), 2.08-1.97 (4H, m, —CH—CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2—CH—), 1.64-1.55 (2H, m, —CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2—), 1.37 (6H, s, H.sub.3C—C(O)O). .sup.13C NMR (125 MHz, CDCl.sub.3, 298K). δ (ppm): 180.13 (—C(O)O), 161.09 (—HC═N—), 156.95 (Ar—C.sub.ortho—), 152.16 (Ar—C.sub.ortho—), 126.42 (Ar—C.sub.meta), 119.18 (Ar—C.sub.ipso), 112.59 (Ar—C.sub.para, Ar—C.sub.meta), 70.21 (—O—CH.sub.2—, —N—CH—), 69.51 (—O—CH.sub.2—, —N—CH—), 69.48 (—O—CH.sub.2—, —N—CH—), 66.26 (—O—CH.sub.2—, —N—CH—), 29.84 (—CH—CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2—CH—), 25.03 (—CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2—), 24.67 (H.sub.3C—C(O)O).

Synthesis of complex 23

[0785] ##STR00140##

[0786] Complex 23 was synthesised by charging a round-bottom flask with LH.sub.2 (1 g, 2.56 mmol), Ba(ClO.sub.4).sub.2 (862 mg, 2.56 mmol) and 100 mL of 1:1 MeOH:CHCl.sub.3. A solution of ethylene diamine (171 μL, 2.56 mmol) in 5 mL of MeOH was added over the course of 10 min before the solution was stirred for a further 2 hours. The solvent was removed under vacuum and the solid dissolved in 300 mL of CHCl.sub.3. Guanidine sulphate (1.34 g, 12.29 mmol) dissolved in 200 mL of deionised water which was subsequently added to the solution and stirred overnight. The layers were separated, and the product extracted into CHCl.sub.3, which was then dried over magnesium sulphate. The solvent was removed under reduced pressure to give a pale yellow solid (656 mg, 62% yield). The resulting solid (570 mg, 1.38 mmol) is dissolved in a 400 mL mixture of 1:1 ratio of methanol and chloroform. NaBH.sub.4 (3×110 mg, 3×2.91 mmol) is added in three portions over the course of an hour and then left to stir overnight. The solvent is removed under vacuum and the resulting solid is treated with 100 mL of deionised water. The solid is then dissolved in 100 mL of dry CHCl.sub.3 and dried over molecular sieves. The sieves are filtered out and the solution evaporated to dryness. The solid is dissolved in minimum amount of CHCl.sub.3 (5 mL), precipitated out with Et.sub.2O (30 mL) and the solid collected by filtration to obtain a pale yellow/cream product.

[0787] Complex 23: .sup.1H NMR (400 MHz, CDCl.sub.3, 298K). δ (ppm): 6.93-6.55 (6H, m, Ar—H), 4.75 (2H, broad s —HN—), 4.30-3.50 (20H, m, —O—CH.sub.2—, —HN—CH.sub.2—CH.sub.2, Ar—CH.sub.2—HN—), 3.26-2.80 (5 h, m, —HN—, H.sub.3C—C(O)O—), 1.55 (3 h, s, H.sub.3C—C(O)O—).

Synthesis of complex 24

[0788] ##STR00141##

[0789] Complex 24 was synthesised by charging a schlenk with potassium benzoate (250 mg, 1.03 mmol) and the pro-ligand (0.40 g, 1.03 mmol) in acetonitrile (40 mL) for an hour under a N.sub.2 atmosphere. Subsequently, ethylene diamine (69 μL, 1.03 mmol) was added and left to the solution was stirred overnight. Next, AIEt.sub.3 (175 μL, 1.08 mmol) was added and the reaction mixture was stirred for a further 16 h at 25° C. Benzoic acid was added (131 mg, 1.08 mmol) and the reaction mixture was heated overnight at 60° C. The solid was dried in vacuo to afford the target complex as a yellow solid.

[0790] Complex 24: .sup.1H NMR (400 MHz, CDCl.sub.3, 298K). δ (ppm): 8.08 (2H, s, —HC═N—), 8.03 (2H, m), 7.51 (1H, m), 7.39 (2H, m), 6.70 (4H, m, Ar—H.sub.meta), 6.41 (2H, t, Ar—H.sub.para, .sup.3J.sub.H-H=7.8 Hz), 4.14-3.70 (16H, m, —O—CH.sub.2—, —N—CH—).

Synthesis of Complex 25

[0791] ##STR00142##

[0792] Complex 25 was synthesised under a nitrogen atmosphere. The appropriate KOAc (0.769 mmol) was added to solution of the ligand (0.30 g, 0.769 mmol) in acetonitrile (15-40 mL) and the solution was stirred for 30 mins, at 25° C. Next, Cr(OAc).sub.2 (0.769 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. Ethylene diamine (0.769 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C. The complexes were oxidized by exposure to air and by the addition of 1 equivalents of acetic acid (44 μL, 0.769 mmol) and the solution was stirred for up to 72 h with reaction progress being monitored using .sup.1H NMR spectroscopy. Once the oxidation was complete, the suspension was filtered, and residual solvent volume reduced in vacuo. Excess acetic acid was removed by azeotropic distillation with toluene (3×50 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

[0793] Complex 25 (33% yield).

Synthesis of Complex 26

[0794] ##STR00143##

[0795] Complex 26 was synthesised under a nitrogen atmosphere. The appropriate KOAc (0.769 mmol) was added to solution of the ligand (0.30 g, 0.769 mmol) in acetonitrile (15-40 mL) and the solution was stirred for 30 mins, at 25° C. Next, Fe(OAc).sub.2 (0.769 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. Ethylene diamine (0.769 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C. The complexes were oxidized by exposure to air and by the addition of 1 equivalents of acetic acid (44 μL, 0.769 mmol) and the solution was stirred for up to 72 h with reaction progress being monitored using .sup.1H NMR spectroscopy. Once the oxidation was complete, the suspension was filtered, and residual solvent volume reduced in vacuo. Excess acetic acid was removed by azeotropic distillation with toluene (3×50 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

Synthesis of complex 27

[0796] ##STR00144##

[0797] Complex 27 was synthesised under a N.sub.2 atmosphere. The appropriate metal acetate ([M(OAc)n], where M=Na, K, Rb, Cs, Ca, Sr or Ba) (1.03 mmol) was added to solution of the pro-ligand (0.40 g, 1.03 mmol) in acetonitrile (15 mL) and the solution was stirred for 30 mins, at 25° C. Next, Co(OAc).sub.2 (0.18 g, 1.03 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. Ethylene diamine (69 μL, 1.03 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C. Acetic acid was removed by azeotropic distillation with toluene (3×25 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

[0798] Complex 27: (0.55 g, 0.88 mmol, 86%)

[0799] FIG. 10 shows an infrared spectrum for complex 27.

Synthesis of complex 28

[0800] ##STR00145##

[0801] Complex 28 was synthesised under a N.sub.2 atmosphere. The appropriate metal acetate ([M(OAc)n], where M=Na, K, Rb, Cs, Ca, Sr or Ba) (1.03 mmol) was added to solution of the pro-ligand (0.40 g, 1.03 mmol) in acetonitrile (15 mL) and the solution was stirred for 30 mins, at 25° C. Next, Co(OAc).sub.2 (0.18 g, 1.03 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. Ethylene diamine (69 μL, 1.03 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C. Acetic acid was removed by azeotropic distillation with toluene (3×25 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

[0802] Complex 28: (0.68 g, 0.91 mmol, 89%)

[0803] FIG. 11 shows an infrared spectrum for complex 28.

Synthesis of complex 29

[0804] ##STR00146##

[0805] Complex 29 was synthesised under a N.sub.2 atmosphere. The appropriate metal acetate ([M(OAc)n], where M=Na, K, Rb, Cs, Ca, Sr or Ba) (1.03 mmol) was added to solution of the pro-ligand (0.40 g, 1.03 mmol) in acetonitrile (15 mL) and the solution was stirred for 30 mins, at 25° C. Next, Co(OAc).sub.2 (0.18 g, 1.03 mmol) was added and the reaction mixture was stirred for a further 2 h at 25° C. Ethylene diamine (69 μL, 1.03 mmol) was added, dropwise, to the reaction mixture and it was stirred for 16 h, at 25° C. Acetic acid was removed by azeotropic distillation with toluene (3×25 mL). The resulting solid was washed with pentane (3×50 mL) and dried in vacuo to afford the target complex as a brown solid.

[0806] Complex 29: (0.63 g, 0.88 mmol, 86%): Anal. Calcd for C.sub.26H.sub.30BaCoN.sub.2O.sub.10 (726.8 g mol.sup.−1): C, 43.0; H, 4.2; N, 3.9%. Found; C, 43.1; H, 4.4; N, 3.9%.

[0807] FIG. 12 shows an infrared spectrum for complex 29.

Synthesis of Complex 30

[0808] ##STR00147##

[0809] Complex 30 was synthesised by combining the dialdehyde pro-ligand (1.02 mmol), Co(OAc).sub.2 (1.02 mmol) and Ca(OAc).sub.2 (1.02 mmol) in dry acetonitrile (15 ml) to form a yellow-orange suspension and stirred at room temperature for 30 mins under a nitrogen atmosphere. To the suspension was added ethylene diamine (1.02 mmol), immediately giving a deep red-brown solution. The solution was stirred overnight at room temperature under a nitrogen atmosphere before adding acetic acid (2.04 mmol) and stirring for three days with the reaction open to air. The solution was filtered to remove the insoluble, unreacted Co(II) species and the brown solution evaporated in vacuo to give a dark brown solid. Azeotropic washes were performed on the solid with toluene (3×50 mL) to remove residual acetic acid, and hexane (3×50 mL) to remove residual toluene. The solid was then dried in vacuo overnight.

[0810] Complex 30 (56% yield): (0.39 g, 0.57 mmol, 56%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 7.81 (2H, s, HC═N) 6.94 (4H, m, meta-ArH) 6.51 (2H, t, para-ArH) 4.49-3.92 (16H, s, O—CH.sub.2—) 1.44 (6H, s, CH.sub.3COO).

[0811] FIG. 13 shows ORTEP representation for the molecular structure of Complex 30 with disorder and hydrogen atoms omitted for clarity and thermal ellipsoids represented at 50% probability.

Complex 31

[0812] ##STR00148##

[0813] Complex 31 was synthesised by combining the dialdehyde pro-ligand (1.02 mmol), Co(OAc).sub.2 (1.02 mmol) and Sr(OAc).sub.2 (1.02 mmol) in dry acetonitrile (15 ml) to form a yellow-orange suspension and stirred at room temperature for 30 mins under a nitrogen atmosphere. To the suspension was added ethylene diamine (1.02 mmol), immediately giving a deep red-brown solution. The solution was stirred overnight at room temperature under a nitrogen atmosphere before adding acetic acid (2.04 mmol) and stirring for three days with the reaction open to air. The solution was filtered to remove the insoluble, unreacted Co(II) species and the brown solution evaporated in vacuo to give a dark brown solid. Azeotropic washes were performed on the solid with toluene (3×50 mL) to remove residual acetic acid, and hexane (3×50 mL) to remove residual toluene. The solid was then dried in vacuo overnight.

[0814] Complex 31 (40% yield): (0.30 g, 0.41 mmol, 40%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ(ppm): 7.73 (2H, s, HC═N) 6.87 (4H, m, meta-ArH) 6.59 (2H, t, para-ArH) 4.55-3.79 (16H, s, O—CH.sub.2—) 1.38 (6H, s, CH.sub.3COO).

Complex 32

[0815] ##STR00149##

[0816] Complex 32 was synthesised by combining the dialdehyde pro-ligand (1.02 mmol), Co(OAc).sub.2 (1.02 mmol) and Ba(OAc).sub.2 (1.02 mmol) in dry acetonitrile (15 ml) to form a yellow-orange suspension and stirred at room temperature for 30 mins under a nitrogen atmosphere.

[0817] To the suspension was added ethylene diamine (1.02 mmol), immediately giving a deep red-brown solution. The solution was stirred overnight at room temperature under a nitrogen atmosphere before adding acetic acid (2.04 mmol) and stirring for three days with the reaction open to air. The solution was filtered to remove the insoluble, unreacted Co(II) species and the brown solution evaporated in vacuo to give a dark brown solid. Azeotropic washes were performed on the solid with toluene (3×50 mL) to remove residual acetic acid, and hexane (3×50 mL) to remove residual toluene. The solid was then dried in vacuo overnight.

[0818] Complex 32 (21% yield): (0.17 g, 0.22 mmol, 21%).sup.1H NMR (400 MHz, CDCl.sub.3, 298 K) δ (ppm): 7.67 (2H, s, HC═N) 6.83 (4H, m, meta-ArH) 6.51 (2H, t, para-ArH) 4.57-3.70 (16H, s, O—CH.sub.2—) 1.45 (6H, s, CH.sub.3COO).

Example 2—Characterisation

.SUP.1.H NMR Spectroscopy

[0819] Successful metalation of the pro-ligand was observed by .sup.1H NMR spectroscopy by observing the reduction of the phenolic oxygen peak at 10.86 ppm and the addition of acetate proton resonances at 0.80-2.00 ppm (CDCl.sub.3, 298 K). Furthermore, a significant up-field shift is observed comparing the aldehyde in the pro-ligand to the imine (where applicable) in the catalyst. The two metal precursors were able to be added together and selectively form Complexes 1-4 due to the size difference of the metals (Co(II); 0.75 Å, Na(1); 1.10 Å, K(I); 1.50 Å, Rb(I); 1.60 Å and Cs(I); 1.70 Å) and the coordination environments in each of the binding cavities (N.sub.2O.sub.2; 1.9 Å, 18-C—6; 2.7 Å).

[0820] Complexes 7-11 are typically highly fluxional at room temperature in solution (CDCl.sub.3, C.sub.2D.sub.2Cl.sub.4), facilitated by the flexible C3 diimine backbone. Variable temperature NMR spectroscopy (328-398 K) permitted the characterisation of these complexes in fast-exchange regimes. Complex 10, distinct in its possession of two acetate co-ligands capping each face of the macrocyclic framework, produces well-defined NMR spectra at room temperature, implying a more rigid ligand conformation enforced by this saturated coordination environment consistent with the solid state structure observed (FIG. 5). Complex 1, on the other hand, shows two different binding modes of the acetate, but one in the NMR implying a fast exchange between the two different binding modes. All of complexes 12, 13 and 14 displayed very low solubility between 298 K and 398 K, which required .sup.13C NMR characterisation by CP-MAS solid state NMR spectroscopy. In general, the observation of 1 imine and 3 crown-ether environments by .sup.1H NMR spectroscopy indicates C.sub.2n time-averaged molecular symmetry. However, Complexes 6, 11, 13, and 15 all display additional splitting of the crown-methylene resonances. This desymmetrisation of the complex is likely caused by increased rigidity in the crown moiety, although unsymmetrical metal binding to the macrocycle cannot be discounted. All complexes are believed to be monomeric in solution and under reaction conditions.

2D DOSY NMR Spectroscopy

[0821] 2D DOSY NMR experiments (CDCl.sub.3, 298 K) result in a single diffusion coefficient for each of complexes 1-4, indicative of a single species in solution. An approximate hydrodynamic radii is calculated using the Stokes-Einstein equation (viscosity of chloroform 0.54 mPa.Math.s) resulting in solution hydrodynamic radii of 5.14 Å, 5.17 Å, 5.65 Å, and 6.66 Å for complexes 1-4, respectively. This hydrodynamic radii in solution agrees well with the hydrodynamic radii calculated in the solid state for complexes 1 and 2, indicating a monomeric complex for both solid and solution states. On the other-hand, complexes 3 and 4 result in smaller hydrodynamic radii in solution state than that calculated for the solid state, suggesting a monomeric nuclearity in solution but dimeric/multimeric in the solid state. This has been previously observed for other complexes that incorporate an 18-crown-6 moiety and is rationalized by the increase ionic radii of Rb and Cs and their accessibility to higher coordination numbers resulting in multimeric species.

MALDI-ToF Mass Spectrum

[0822] The MALDI-ToF mass spectrum displays peaks at 495 m/z, 511 m/z and 604 m/z corresponding to the molecular cation, [pro-ligand-Co(II)M.sup.2]+ for complexes 1, 2 and 4, respectively. Furthermore, the isotropic distribution pattern measured match that which was computed for the molecular formula of Complexes 1-4.

Paramagnetism Studies

[0823] The Ni(II) complexes, 8 and 16 were both observed to be paramagnetic, μ=2.47 and 2.57 BM respectively. Attempts to characterise the complexes by X-band electron paramagnetic resonance (EPR) spectroscopy were unsuccessful; EPR silence of Ni(II) complexes can result from large zero field splitting, rendering active transitions unobservable.

[0824] Although concentrated samples (10 mM, toluene) of Ni complexes did produce a weak resonance at g=1.999, by comparison to an 2.7 mM Cu(II) standard (Cu-tetraphenyl porphyrin), the approximate concentration of this weak component was determined at <1 nM. This is proposed to arise from a Ni(II)/Ni(Ill) equilibrium, with spin density localised at the phenolate moiety, as has previously been observed in paramagnetic phenolate complexes.

Crystallographic Studies

[0825] The structure of the prepared complexes could in some cases be confirmed by X-ray crystallography:

Complexes 1 and 2

[0826] Crystals suitable for single crystal X-ray diffraction were obtained via vapor diffusion of pentane (Complex 1) or diethyl ether (Complex 2) into a saturated solution of complex in dichloromethane and are shown in FIGS. 1 and 2 respectively. Structural elucidation confirmed the formation of the desired heterodinuclear complexes. Complexes 1 and 2 were shown to be isostructural, both monomeric in the solid state with an O.sub.h cobalt centre occupying the imine-phenol cavity and the group 1 metal occupying the crown-ether moiety. There is a measurable increase in the Co-M.sup.2 distance (M.sup.2−Na=3.388 Å, K=3.698 Å, Rb=3.877 Å) consistent with the larger van der Waal radii of potassium in comparison to sodium. One acetate is shown to bridge between the cobalt centre and the alkali metal centre whereas the other is terminal on the cobalt. The structures of Complexes 1 and 2 suggest the formation of a cobalt ‘ate’ species.

Complexes 7, 10, 12 and 15

[0827] Single crystals suitable for X-ray diffraction were obtained for Complexes 7, 10, 12 and 15 from slow evaporation of CHCl.sub.3 solutions. Crystals of Complex 7-(EtOH) were obtained from slow evaporation of an ethanol solution and crystals from complex 10 were obtained from slow diffusion of pentane into dichloromethane. Complex 7, Complex 7-(EtOH) and Complex 10, adopt monomeric structures in the solid-state, while Complex 12 was observed to be dimeric with bridging acetate ions. All of the Complexes demonstrate the formation of ‘ate’ complexes with the anionic acetate oxygen localised at the transition metal, as evidenced by the unsymmetrical C—O bond distances of the co-ligand and short M-O distances of towards the metal in the salen moiety. This is most dramatically illustrated in Complex 7-(EtOH), which displays acetate binding at zinc, alongside one ethanol molecule bound at the sodium ion. The formation of ‘-ate’ complexes allows for the retention of a Lewis acidic sodium ion, predisposed towards epoxide coordination. Interestingly, Complex 10 shows two acetates bridging between the cobalt and the sodium while Complex 1 has one bridging and one monodentate acetate. Complex 15 forms a coordination polymer linked intramolecularly by bridging acetate co-ligands, either causing, or resulting from, significant distortion of the solid-state structure, with highly unsymmetrical binding of sodium to the crown-ether moiety. In the context of these data, it is possible to contrast the C, molecular symmetry of Complex 15 (inferred from NMR spectroscopy), with the C.sub.2n symmetry inferred from the highly fluxional .sup.1H NMR observed for Complex 7, despite their similar C3 N,N′-backbones.

Example 3—Polymerisation Studies

[0828] The synthesised complexes were explored as catalysts for the copolymerisation of a variety of epoxide monomers, including PO and CHO:

Propylene Oxide

[0829] Complexes 1-4 were tested in the ROCOP of CO.sub.2/PO with 3.5 mM catalyst, neat PO (6 mL, 14 M), 20 bar CO.sub.2 pressure at 50° C. Conversions were calculated using .sup.1H NMR by comparison of the methine proton on PO (4.92 ppm) against an internal standard (mesitylene 10 equiv.).

[0830] The polymerisation results are presented in Table 1 below:

TABLE-US-00001 TABLE 1 PO ROCOP in the presence of CO.sub.2 using complexes 1-4.sup.a as well as selected catalysts from the literature k.sub.p ×10.sup.3 M.sub.n (dm.sup.3 [Ð] Time Conv. CO.sub.2 Polym. TOF mol.sup.−1 (kg Entry Complex (h) (%) .sup.b (%).sup.c (%).sup.d TON.sup.e (h.sup.−1).sup.f s.sup.−1).sup.g mol.sup.−1).sup.h 1 1 5 15 >99 79 584 117 2.09 2.3 [1.08] 2 2 4 34 >99 98 1352 326 11.20 5.9 [1.10] 3 2 4 25 >99 94 976 266 6.50 9.4 [1.04] 4 2 21 48 >99 94 1920 89 2.47 33.8 [1.04] 16.2 [1.04] 5 2 24 21 >99 83 820 34 0.73 33.7 [1.11] 14.4 [1.04] 6.sup.i 2 1.4 28 >99 93 1126 834 24.0 5800 [1.07] 7.sup.j 2 19.8 90 >99 98 1790 91 10.70 8800 [1.04] 8 3 23 31 >99 91 1216 52 1.77 6.5 [1.07] 9 4 23 27 >99 84 1049 46 1.76 5.6 [1.08] 10.sup.K19 [(Salen)Co(2,4-NP)]/18C6/KI 3.0 27 >99 41 540 182 — 4700 [1.43] 11.sup.L20 [(Salcy)Co(O.sub.2CCF.sub.3)[PPN(O.sub.2CCF.sub.3) 48 95 >99 >99 475 10 — 7800 [1.06] (20 H.sub.2O) 12.sup.M21 [(Salen[Pip.sup.+].sub.2)Co(OAc).sub.2] (20 20 95 >99 96 1900 95 — 5100 [1.06] MeOH) 13.sup.N22 [(Salen[NBu.sub.3.sup.+].sub.4)Co(OAc)](NO.sub.2).sub.4 (400 1 10 >99 >99 10,300 10,300 — 2600 [1.05] adipic acid) 14.sup.O23 Et.sub.3B:[NBu.sub.4.sup.+].sub.2[O.sub.3C.sup.2−] 14 95 91 95 37 3 — 4100 [1.10] 15.sup.P24 Zn—Co-DMCC (15 sebacic 30 64 75 98 1280 g/g 43 g/g/h — 1500 [1.10] acid) .sup.aReaction conditions: catalyst (0.025 mol %), PO (6 mL, 14M), 1,2-cyclohexene diol (0.5 mol %, 70 mM), 20 bar CO.sub.2, 50° C., except for entries 3, 4 and 5, where 0.25 mol %, 0.125 mol % and 0 mol % respectively of 1,2-cyclohexene diol were used. .sup.b Expressed as a percentage of PO conversion vs the theoretical maximum (100%); determined from the .sup.1H NMR spectrum by comparison of the relative integrals of the resonances assigned to the polycarbonate (4.92 ppm), cyclic carbonate (4.77 ppm) and polyether (3.46-3.64 ppm) against the internal standard mesitylene (6.70 ppm, 10 equiv.). .sup.cExpressed as a percentage of CO.sub.2 uptake vs the theoretical maximum (100%); determined by comparison of the relative integrals of the .sup.1H NMR resonances due to polycarbonate (4.92 ppm) and cyclic carbonate (4.77 ppm) against polyether (3.46-3.64 ppm). .sup.dExpressed as a percentage of polymer formation vs the theoretical maximum (100%); determined by comparison of the relative integrals of the .sup.1H NMR resonances due to polycarbonate (4.92 ppm) against cyclic carbonate (4.77 ppm). .sup.eTurn-over number (TON) = number of moles of PO consumed/number of moles catalyst. .sup.fTurn-over frequency (TOF) = TON/time (h). .sup.gk.sub.p = k.sub.obs/[cat].sup.1; k.sub.obs determined as the gradient of the semi-logarithmic plot of In[PO].sub.t/[PO].sub.0 vs time. .sup.hDetermined by GPC, in THF, calibrated using narrow-M.sub.n polystyrene standards. .sup.iCatalyst (0.025 mol %, 3.5 mM), PO (6 mL, 14M), 1,2-cyclohexanediol (0.5 mol %, 70 mM), 30 bar CO.sub.2, 70° C. .sup.JCatalyst (0.025 mol %, 3.5 mM), PO (3 mL, 7M) Diethylcarbonate (3 mL), 1,2-cyclohexanediol (0.5 mol %, 70 mM), 20 bar CO.sub.2, 50° C. .sup.KCatalyst (0.05 mol %, 7.1 mM), PO (14 mL, 14M), KI (0.05 mol %, 7.1 mM), 15 bar CO.sub.2, 25° C. .sup.LCatalyst (0.2 mol %, 10.0 mM), PO (0.5 mL, 4.6M) Toluene/Chloroform (1 mL), PPNX (0.2 mol %, 10.0 mM), H.sub.2O (2.0 mol %, 1M), 15 bar CO.sub.2, 25° C. .sup.MCatalyst (0.05 mol %, 7.2 mM), PO (1 mL, 7M) 1,2-dimethoxyethane (1 mL), Methanol (1.0 mol %, 0.14M), 14 bar CO.sub.2, 25° C. .sup.NCatalyst (0.001 mol %, 1.7 μM), PO (12 mL, 14M), adipic acid (0.4 mol %, 0.68M), 25 bar CO.sub.2, 75° C. .sup.OCatalyst (7.5 mol %, 0.25M, 1 mL from a 1M THF solution), tributyl ammonium carbonate (TBAC) (2.5 mol %, 0.09M), PO (2 mL, 7M), THF (1 mL), 10 bar CO.sub.2, 40° C. .sup.PCatalyst (50 mg), PO (100 mL, 14M), sebacic acid (95 mmol, 0.95M), 40 bar CO.sub.2, 50° C.

[0831] Table 1 shows that the catalysts of the present invention (entries 1-9, Table 1), in particular complex 2, exhibit excellent catalytic performance in terms of activity, selectivity and yields for PPC polyols with very high CO.sub.2 uptake. Additionally, the data highlights the ability of the catalysts of the present invention to prepare low molar mass polycarbonate polyols with high efficiency without the need for unfeasibly large acid loading.

[0832] By utilizing data obtained through catalytic loading experiments, a plot of molar mass (kg mol.sup.−1) vs turn-over number (TON) can be obtained (FIG. 6a). A linear increase in molar mass vs TON is observed whilst maintaining narrow, monomodal dispersity (Ð<1.10) indicative of well-controlled polymerisations.

[0833] A primary disadvantage to the traditional salen:cocatalyst combination for ROCOP catalysis is the complexity of the resultant rate law. Often reported to have a dependence in catalyst order between 1 and 2, with a cocatalyst dependence of between 0.5 and 2, a first order dependence in epoxide concentration and a zeroth order in CO.sub.2 pressure. The complexity of the rate law has led to a lack of understanding of the role of cocatalyst, whether it solely provides an attacking nucleophile for ring-opening, stabilizes the metal-containing Salen species to provide the attacking nucleophile or a combination is yet to be fully resolved as its role also appears dependent on both its ratio towards catalyst and concentration. Having a thorough understanding of the rate law underpinning the polymerisation process of the present invention will facilitate future industrial optimisation and scale up.

[0834] To determine the order dependence in epoxide concentration, 3.57 mM of Complex 2 was dissolved in a 50:50 mixture of PO:diethyl carbonate (total volume 6 mL) with a resulting PO concentration of 7M and heated to 50° C. A sigmoidal feature in the conversion time plot was observed which may correspond to poor initiation under dilution. A semi-logarithmic plot of epoxide concentration vs. time (ln([PO].sub.t/[PO].sub.0) vs t) from 30-90% epoxide conversion showed a linear relationship (k.sub.obs=3.82×10.sup.−5 s.sup.−1 R.sup.2=0.9992) indicative of a first order dependence on epoxide concentration (FIG. 7a).

[0835] To determine the order dependence in catalyst concentration, a series of PO/CO.sub.2 ROCOP reactions were carried out in neat PO (14 M), 20 bar CO.sub.2 at 50° C. using a range of Complex 2 concentrations (1.56-7.13 mM). All polymerization reactions afforded perfectly alternating PPC with no ether linkages or significant cyclic carbonate (<5%) by-products observed by H NMR spectroscopy. A linear relationship between the logarithm of the observed rate and the logarithm of catalyst concentration (ln(k.sub.obs) vs ln([cat])) was observed with a gradient of 0.96 (R.sup.2=0.9526) indicating a first order dependence on catalyst concentration (FIG. 7b).

[0836] The dependence on CO.sub.2 pressure was determined by measuring the observed rate constant (k.sub.obs) across the CO.sub.2 pressure range 5-30 bar using 3.57 mM catalyst, neat PO (14 M) at 50° C. A plot of observed rate constant versus pressure (k.sub.obs vs P.sub.CO2) resulted in an approximate zeroth order dependence on CO.sub.2 pressure between 10-25 bar. A decrease in rate is observed at pressures<10 bar and is attributed to the increased formation of cyclic carbonate. At CO.sub.2 pressures>20 bar a decrease in activity is observed, in line with previous observations and may be due to CO.sub.2 gas expansion reducing the overall catalyst and epoxide concentrations (FIG. 7c).

Rate=[Cat].sup.1[PO].sup.1[CO.sub.2].sup.0

[0837] Overall, the reaction operates via an approximate second order rate law; first order in both catalyst and epoxide concentrations and a near zeroth order in CO.sub.2 pressure. This is in-line with previously reported dinuclear systems for CO.sub.2/CHO copolymerisation and matches the simplified rate laws obtained using the quaternary ammonium salt appended salens.

[0838] Certain complexes were tested in the ROCOP of CO.sub.2/PO. The polymerisation results are presented in Tables 1a to 1d below.

TABLE-US-00002 TABLE 1a Polymerization data for PO/CO.sub.2 ROCOP using complexes 17-22.sup.a PPC k.sub.obs, PPC*10.sup.5/ k.sub.p *10.sup.2 M.sub.n, exp. Selec. Conversion TOF.sub.PPC TOF.sub.CC k.sub.obs, CC*10.sup.5 (dm.sup.3 (g mol.sup.−1) Complex (%) (%) TON (h.sup.−1) (h.sup.−1) (s.sup.−1) mol.sup.−1 s.sup.−1) [Ð] 22 81 26 1051 117 28 8.66/5.31 2.42/1.49 4600 [1.10] 17 >99 24 973 389 0 15.3 4.29 4000 [1.06] 18 12.3 9 347 2 16 .sup. —/2.67 .sup. —/0.747 — 19 80 30 1196 73 19 4.39/0.145 1.23/0.0406 4400 [1.11] 20 85 35 1377 101 17 6.82/1.20 1.91/0.336 5500 [1.15] 21 96 37 1493 191 8 6.46/2.16 1.81/0.604 8900 [1.11] .sup.aReaction conditions: Catalyst (0.025 mol %, 3.5 mM), PO (6 mL, 14M), 1,2-cyclohexanediol (0.5 mol %, 70 mM), 20 bar CO.sub.2, 50° C.

TABLE-US-00003 TABLE 1b Polymerization data for PO/CO.sub.2 ROCOP using complex 24 CO.sub.2 PPC M.sub.n, exp. Time selectivity Selectivity Conversion TOF.sub.PPC TOF.sub.CC (g mol.sup.−1) Complex (h) (%) (%) (%) (h.sup.−1) (h.sup.−1) [Ð] 24 23 62 16 12 0.5 1.3 —

TABLE-US-00004 TABLE 1c Polymerization data for PO/CO.sub.2 ROCOP using complexes 1-4.sup.a M.sub.n Co(III)/ Time Conv. CO.sub.2 Polym. TOF [Ð] Complex M(I) (h) (%).sup.b (%).sup.c (%).sup.d TON.sup.e (h.sup.−1).sup.f (g mol.sup.−1).sup.h 1 Na 5.0 15 >99 79 600 120 2300 [1.08] 2 K 4.0 34 >99 98 1360 340 5900 [1.10] 2 K 1.4 28 >99 93 1120 800 5800 [1.07] 2 K 19.8 90 >99 98 1800 91 8800 [1.04] 3 Rb 23 31 >99 91 1240 54 6500 [1.07] 4 Cs 23 27 >99 84 1080 47 5600 [1.08] .sup.aReaction conditions: Catalyst (0.025 mol %, 3.5 mM), PO (6 mL, 14M), 1,2-cyclohexanediol (0.5 mol %, 70 mM), 20 bar CO.sub.2, 50° C.

TABLE-US-00005 TABLE 1d Polymerization data for PO/CO.sub.2 ROCOP using complexes 27 and 29.sup.a M.sub.n Co(II)/ Time Conv. Polym. TOF [Ð] Complex M(II) (h) (%).sup.b CO.sub.2 (%).sup.c (%).sup.d TON.sup.e (h.sup.−1).sup.f (g mol.sup.−1).sup.h 27 Ca 24 Trace >99 >99 — — — 29 Ba 24 7 >99 >99 263 12 7200 [1.10] .sup.aReaction conditions: Catalyst (0.025 mol %, 3.5 mM), CHO (6 mL, 9.9M), 1,2-cyclohexanediol (0.5 mol %, 70 mM), 20 bar CO.sub.2, 50° C.

[0839] An investigation into the temperature dependence on rate and selectivity of PO/CO.sub.2 ROCOP using Complex 2 was also undertaken across the temperature range 40-70° C. The polymerizations were carried out with a 3.57 mM catalyst loading, neat PO (14 M) under high CO.sub.2 pressure (20 bar). The polymerisation results are presented in Table 2 below:

TABLE-US-00006 TABLE 2 Temperature dependence of CO.sub.2/PO on complex 2 k.sub.p ×10.sup.3 (dm.sup.−3 Mn Temp Time Conv CO.sub.2 Polym TOF mol.sup.−1 (kg mol.sup.−1) Entry (° C.) (h) (%).sup.b (%).sup.c (%).sup.d TON.sup.e (h.sup.−1).sup.f s.sup.−1).sup.g [Ð].sup.h 1 40 6.5 22 >99 97 870 134 3.4 3.9 [1.07] 2 45 4.1 24 >99 95 925 226 5.1 4.2 [1.07] 3 50 3.2 32 >99 >99 1285 408 10.0 5.9 [1.07] 4 55 2.9 34 >99 92 1328 455 11.6 5.2 [1.07] 5 60 2.0 28 >99 92 1124 577 14.1 5.6 [1.08] 6 70 1.4 30 >99 63 1180 833 17.4 4.1 [1.08] 7* 70 1.4 28 >99 93 1126 834 24.0 5.8 [1.07] .sup.aReaction conditions: catalyst (0.025 mol %), PO (6 mL, 14M), CTA (20 equiv.), 20 bar CO.sub.2. .sup.bExpressed as a percentage of PO conversion vs the theoretical maximum (100%); determined from the .sup.1H NMR spectrum by comparison of the relative integrals of the resonances assigned to the polycarbonate (4.92 ppm), cyclic carbonate (4.77 ppm) and polyether (3.46-3.64 ppm) against the internal standard mesitylene (6.70 ppm, 10 equiv.). .sup.cExpressed as a percentage of CO.sub.2 uptake vs the theoretical maximum (100%); determined by comparison of the relative integrals of the .sup.1H NMR resonances due to polycarbonate (4.92 ppm) and cyclic carbonate (4.77 ppm) against polyether (3.46-3.64 ppm). .sup.dExpressed as a percentage of polymer formation vs the theoretical maximum (100%); determined by comparison of the relative integrals of the .sup.1H NMR resonances due to polycarbonate (4.92 ppm) against cyclic carbonate (4.77 ppm). .sup.eTurn-over number (TON) = number of moles of PO consumed/number of moles catalyst. .sup.fTurn-over frequency (TOF) = TON/time (h). .sup.gk.sub.p = k.sub.obs/[cat].sup.1; k.sub.obs determined as the gradient of the semi-logarithmic plot of In[PO].sub.t/[PO].sub.0 vs time. .sup.hDetermined by GPC, in THF, calibrated using narrow-M.sub.n polystyrene standards. *30 bar CO.sub.2

[0840] All polymerisations displayed excellent CO.sub.2 uptake (>99%) with trace polyether linkages observed by .sup.1H NMR spectroscopy. An increase in activity was observed from 134 h.sup.−1 to 834 h.sup.−1 at 40° C. and 70° C., respectively. At 70° C., 20 bar CO.sub.2, a decrease in polymer selectivity from 93% to 63% was observed and concurrently an increase in PC was measured. Carrying out the reaction at an elevated CO.sub.2 pressure (30 bar) negated the formation of cyclic carbonate and restored polymer selectivity>90%. Furthermore, all polymerizations resulted in well-controlled, monomodal, polymer distributions (Ð<1.1).

Cyclohexene Oxide

[0841] The synthesised complexes were also explored as catalysts for ROCOP of CO.sub.2/CHO. Polymerisations were typically run at 1 bar CO.sub.2 pressure and 100° C. with 10 equivalence of trans-1,2-cyclohexanediol as chain transfer agent (CTA) producing low molecular weight polyols. The catalyst loading was varied for the higher rate complexes to avoid high viscosity regime. The polymerisation results are presented in Table 3 below:

TABLE-US-00007 TABLE 3 polymerisation data for CO.sub.2/CHO ROCOP with various complexes.sup.j M.sub.n Time Temperature PCHC TOF (g .Math. mol.sup.−1) Entry Complex (h) (° C.) Selectivity.sup.a Conversion.sup.b TON.sup.c (h.sup.−1).sup.d [Ð].sup.e 1.sup.f 7 26 80 >99% 30% 301 12 1500 [1.13] 2.sup.f 5 8 100 94% 24% 235 29 1700 [1.13] 3.sup.f 12 8 100 97% 27% 265 33 2000 [1.17] 4.sup.f 15 14 100 93% 32% 318 23 2500 [1.13] 5.sup.f 9 20 80 73% 4% 29 1.5 n.d. 6.sup.f 6 24 100 48% 18% 177 7 400 [1.43] 7.sup.f 13 24 100 43% 14% 140 6 400 [133] 8.sup.f 11 22 100 — 0% 0 0 n.d. 6.sup.f 8 4 100 >99% 22% 222 56 2000 [1.11] 10.sup.f 16 4 100 98% 41% 412 103 3100 [1.14] 11.sup.f 10 14 100 95% 58% 581 42 3000 [1.17] 12.sup.g 1 0.5 100 >99% 16% 795 1590 5300 [1.07] 2200 [1.05] 13.sup.h 1 1 120 >99% 17% 4343 4343 15700 [1.03] 6700 [1.17] 14.sup.i 14 4 100 >99% 48% 480 119 3700 [1.17] .sup.aSelectivity for PCHC against trans-cyclohexene carbonate (no ether observed). Measured by integration of .sup.1H NMR resonances for cyclic carbonate (δ 4.00 ppm) and ether linkages (δ 3.45 ppm) against PCHC (δ 4.65 ppm). .sup.bCyclohexene oxide consumed as a percentage of total starting amount, determined by .sup.1H NMR spectroscopy. .sup.cTurnover number (TON) = moles of CHO consumed/moles catalyst, moles of CHO consumed determined by the addition of integrals of .sup.1H NMR resonances of cyclic carbonate (δ 4.00 ppm) and PCHC (δ 4.65 ppm) over addition of CHO (δ 3.05 ppm), cyclic carbonate (δ 4.00 ppm) and PCHC (δ 4.65 ppm), multiplied by initial moles of CHO. .sup.dTurnover frequency (TOF) = TON/time. .sup.eDetermined by SEC, in THF, calibrated against narrow M.sub.n polystyrene standards; polydispersity given in square brackets. .sup.f0.1 mol % catalyst loading; .sup.g0.02 mol % catalyst loading, 1:10:4000. .sup.h0.004 mol % catalyst loading, 1:10:25000, 120° C., 20 bar CO.sub.2. .sup.i0.02 mol % catalyst loading .sup.jCatalysis conditions:catalyst:CHD:CHO 1:10:1000, 1 bar pressure CO.sub.2 and in neat epoxide.

[0842] The turnover frequencies (TOFs) span 4 orders of magnitude (0-1590 h.sup.−1) at 1 bar CO.sub.2 pressure, while selectivity for polycyclohexene carbonate (PCHC) formation ranges from 43->99%. In general, the onset of trans-cyclic carbonate formation becomes significant above 100° C., although this barrier was lower for selected catalysts. For all magnesium catalysts, lower TOFs (0-7 h.sup.−1) and lower selectivities for PCHC formation (43-73%) are observed, the latter driven by competitive trans-cyclic carbonate formation (Table 3, entries 5-7). The zinc catalysts were moderately active (12-33 h.sup.1) and in the case of Complex 7, no side products could be detected by .sup.1H NMR spectroscopy. Across the zinc series, the more flexible C3 backbone in Complex 7 appears to decrease polymerisation rate (Table 3, entries 1-3), while use of the diamine variant complex 15 led to a slight increase in activity alongside a concomitant decrease in selectivity (Table 3, entries 1 and 4).

[0843] Significant improvements were observed for the nickel analogues, with Complex 16 displaying TOFs up to 103 h.sup.−1 at 98% selectivity (Table 3, entries 9 and 10). However, most remarkable is the observed variation in polymerisation rate for the cobalt series (Table 3, entries 11, 13 and 14), with a greater than 30-fold rate acceleration observed on substituting the aliphatic C3 and C2 backbones. For Complex 1, a TOF of 1590 h.sup.−1 was recorded, making this the most active, highly selective catalyst for CHO/CO.sub.2 ROCOP at 1 bar CO.sub.2 reported to date. Increasing the polymerisation temperature to 120° C. led to the accelerated formation of trans-cyclic carbonate. Increasing the CO.sub.2 pressure to 20 bar in a stainless-steel reactor with improved stirring efficiency allowed for increased TOFs of 4343 h.sup.1 at 120° C. (Table 3, entry 13).

[0844] Given the impressive activity of Complex 1, the polymerisation kinetics were studied by in-situ FTIR spectroscopy as dilute solutions in diethyl carbonate. A close to first-order kinetics with respect to the catalyst was observed as can be seen from the linear log plots of k.sub.obs vs concentration of the catalyst (FIGS. 8c and 8d). This is qualitatively supported by the very high TOFs accessible at very low catalyst loading ([CHO]:[Cat]=1:25000, Table 3, entry 13). The order in epoxide was determined by a log plot of concentration over time from 5-70% conversion (FIG. 8a). The data shows a linear decrease of ln([CHO]/[CHO]o), indicating a first order dependence in [CHO]. No statistically significant correlation was observed between CO.sub.2 pressure and rate, demonstrating a zero-order gas dependence (FIG. 8b).

Other Epoxide Monomers

[0845] Complex 2 was tested in the ROCOP of CO.sub.2 with a series of acyclic and cyclic epoxide monomers. The polymerisation results are presented in Table 4 below:

TABLE-US-00008 TABLE 4 monomer scope for ROCOP of CO2/epoxide using complex 2.sup.a Time Conv. CO.sub.2 Polym TOF k.sub.p ×10.sup.3 M.sub.n [Ð] Entry Epoxide (h) (%).sup.b (%).sup.c (%).sup.d TON.sup.e (h.sup.−1).sup.f (dm.sup.3 mol.sup.−1 s.sup.−1).sup.g (kg mol.sup.−1).sup.h 1 Acyclic PO 4.2 34 >99 >99 1352 326 11.2 5.9 [1.10] 2 vPO 23.5 60 >99 >99 2091 89 5.9 4.1 [1.30] 3 AGE 5.6 51 >99 >99 1220 219 15.4 3.9 [1.28] 4 .sup.tBGE 7.9 >99 92 908 116 7.39 5.1 [1.15] 5 Cyclic CHO 2.3 52 >99 >99 1430 631 31.7 5.9 [1.10] 6 vCHO 3.2 60 >99 >99 1285 408 24.6 9.5 [1.08] 7 CPO 6.3 32 >99 95 1062 162 5.1 4.2 [1.07] .sup.aReaction conditions: catalyst (3.57 mM), neat epoxide (6 mL), CTA (20 equiv.), 20 bar CO.sub.2, 50° C. .sup.bExpressed as a percentage of PO conversion vs the theoretical maximum (100%); determined from the .sup.1H NMR spectrum by comparison of the relative integrals of the resonances assigned to the polycarbonate (4.81 ppm, 1H), cyclic carbonate (4.38 ppm, 1H) and polyether (3.30-3.55 ppm, 3H) against an internal standard mesitylene (6.59 ppm, 10 equiv. (30H)). .sup.cExpressed as a percentage of CO.sub.2 uptake vs the theoretical maximum (100%); determined by comparison of the relative integrals of the .sup.1H NMR resonances due to polycarbonate (4.81 ppm, 1H) and cyclic carbonate (4.38 ppm, 1H) against polyether (3.30-3.55 ppm, 3H). .sup.dExpressed as a percentage of polymer formation vs the theoretical maximum (100%); determined by comparison of the relative integrals of the .sup.1H NMR resonances due to polycarbonate (4.81 ppm, 1H) against cyclic carbonate (4.38 ppm, 1H). .sup.eTurn-over number (TON) = number of moles of PO consumed/number of moles catalyst. .sup.fTurn-over frequency (TOF) = TON/time (h). .sup.gkp = k.sub.obs/[cat].sup.1; k.sub.obs determined as the gradient of the semi-logarithmic plot of In[PO].sub.t/[PO].sub.0 vs time, [cat] = 3.57 mM. .sup.hDetermined by GPC, in THF, calibrated using narrow-M.sub.n polystyrene standards. PO = propylene oxide, vPO = vinyl propylene oxide, AGE = allyl glycidyl ether, .sup.tBGE = tert-butyl glycidyl ether, CHO = cyclohexene oxide, vCHO = vinyl cyclohexene oxide, CPO = cyclopentene oxide.

[0846] Overall, the catalyst displayed excellent CO.sub.2 selectivity (>99%) with no polyether linkages observed by .sup.1H NMR spectroscopy. Excellent polycarbonate selectivity (>95%) with trace quantities of cyclic carbonate (<5%) was observed, with the exception of styrene oxide (SO).

[0847] On the whole, cyclic epoxides proceeded with a higher rate constant in comparison to acyclic examples. Furthermore, the 6-membered ring epoxides (CHO and vCHO) proceeded faster than 5-membered ring epoxides (CPO).

[0848] Cyclopentene oxide is a particularly interesting epoxide monomer as its polycarbonate shows unusual depolymerization to recover the monomer (instead of backbiting to trans-cyclopentene carbonate) thus accessing potential for recyclable polymers. The copolymerization of cyclopentene oxide with CO.sub.2 showed excellent selectivity (95%) with trace cis-cyclopenetene oxide (5%) observed by .sup.1H NMR spectroscopy (Table 4, Entry 10). An activity of 162 h.sup.−1 was observed under the optimized conditions (0.025 mol % cat, 50° C., 20 bar CO.sub.2, neat CPO). This represents a 4-fold increase in activity compared to the best reported cobalt-salen with a tethered quaternary ammonium salt (42 h.sup.−1, 0.1 mol % cat, 50° C., 20 bar CO.sub.2) and a 2-fold increase in activity compared to its chromium derivative (77 h.sup.−1, 0.1 mol % cat, 70° C., 20 bar CO.sub.2)..sup.25

[0849] While specific embodiments of the invention have been described herein for the purpose of reference and illustration, various modifications will be apparent to a person skilled in the art without departing from the scope of the invention as described by the appended claims.

REFERENCES

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POLYMERISATION PROCESS

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C08G64/0208

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B01J31/2217

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C08G64/34

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C08G64/34

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Abstract

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