Oxo-nitrogenated iron complex, catalytic system comprising said oxo-nitrogenated iron complex and process for the (co)polymerization of conjugated dienes

Abstract

An oxo-nitrogenated iron complex having general formula (I) or (II) wherein: R.sub.1 and R.sub.2 identical or different, represent a hydrogen atom; or are selected from linear or branched, optionally halogenated C.sub.1-C.sub.20, preferably C.sub.1-C.sub.15, alkyl groups, optionally substituted cycloalkyl groups, optionally substituted aryl groups; R.sub.3, identical or different, represent a hydrogen atom; or are selected from linear or branched, optionally halogenated C.sub.1-C.sub.20, preferably C.sub.1-C.sub.15, alkyl groups, optionally substituted cycloalkyl groups, optionally substituted aryl groups; X.sub.1 and X.sub.2, identical or different, represent a halogen atom such as, for example, chlorine, bromine, iodine; or are selected from linear or branched C.sub.1-C.sub.20, preferably C.sub.1-C.sub.15, alkyl groups, OCOR.sub.4 groups or OR.sub.4 groups wherein R.sub.4 is selected from linear or branched C.sub.1-C.sub.20, preferably C.sub.1-C.sub.15, alkyl groups. Said oxo-nitrogenated iron complex having general formula (I) or (II) can be advantageously used in a catalytic system for the (co)polymerization of conjugated dienes. ##STR00001##

Claims

1. A catalytic system for the (co)polymerization of conjugated diener comprising: a) at least one oxo-nitrogenated iron complex having general formula (I) or (II): ##STR00019## wherein: each of R.sub.1 and R.sub.2; R.sub.3 is an unsubstituted phenyl group; and each of X.sub.1 and X.sub.2 is a chlorine atom; and b) at least one co-catalyst selected from organic compounds of an element M different from carbon, said element M being selected from elements belonging to groups 2, 12, 13, or 14 of the Periodic Table of the Elements.

2. The catalytic system for the (co)polymerization of conjugated dienes according to claim 1, wherein said co-catalyst (b) is selected from (b.sub.1) aluminum alkyls having general formula (III):
Al(X).sub.n(R.sub.5).sub.3-n(III) wherein said element M different from carbon includes said Al atom, X represents a halogen atom; R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, or aryl groups, said groups being optionally substituted with one or more atoms of silicon or germanium; and n is an integer ranging from 0 to 2.

3. The catalytic system for the (co)polymerization of conjugated dienes according to claim 2, wherein said aluminum alkyls (b.sub.1) having general formula (III) are di-ethyl-aluminum chloride (DEAC), mono-ethyl-aluminum dichloride (EADC), or ethyl aluminum-sesquichloride (EASC).

4. The catalytic system for the (co)polymerization of conjugated dienes according to claim 1, wherein said co-catalyst (b) is selected from (b.sub.2) organo-oxygenated compounds of said element M different from carbon belonging to groups 13 or 14 of the Periodic Table of Elements.

5. The catalytic system for the (co) polymerization of conjugated dienes according to claim 4, wherein said organo-oxygenated compounds (b.sub.2) are selected from aluminoxanes having general formula (IV):
(R.sub.6).sub.2AlO[Al(R.sub.7)O].sub.pAl(R.sub.8).sub.2(IV) wherein said element M different from carbon includes said Al atoms, R.sub.6, R.sub.7 and R.sub.8, identical or different, represent a hydrogen atom, a halogen atom; or are selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, or aryl groups, said groups being optionally substituted with one or more atoms of silicon or germanium; and p is an integer ranging from 0 to 1000.

6. The catalytic system for the (co)polymerization of conjugated dienes according to claim 5, wherein said organo-oxygenated compound (b.sub.2) is methylaluminoxane (MAO).

7. The catalytic system for the (co)polymerization of conjugated dienes according to claim 1, wherein said co-catalyst (b) is selected from (b.sub.3) compounds or mixtures of organometallic compounds of said element M different from carbon able to react with the oxo-nitrogenated iron complex having general formula (I), extracting from this a -linked substituent X.sub.1 or X.sub.2, to form on the one hand at least one neutral compound, and on the other hand an ionic compound consisting of a cation containing the metal (Fe) coordinated by the ligand, and an organic non-coordinating anion containing the metal M, whose negative charge is delocalized on a multicentric structure.

8. The catalytic system for the (co)polymerization of conjugated dienes according to claim 7, wherein said compounds or mixtures of compounds (b.sub.3) are selected from organic compounds of aluminum or boron, including those represented by the following general formulae:
[(R.sub.C).sub.WH.sub.4-W].Math.[B(R.sub.D).sub.4]; B(R.sub.D).sub.3; Al(R.sub.D).sub.3; B(R.sub.D).sub.3Pyr; [Ph.sub.3C]+.Math.[B(R.sub.D).sub.4];
[(R.sub.C).sub.3PyrH]+.Math.[B(R.sub.D).sub.4];
[Li]+.Math.[B(R.sub.D).sub.4]; [Li]+.Math.[Al(R.sub.D).sub.4] wherein said element M different from carbon includes said Al atom or said B atom, w is an integer ranging from 0 to 3, each R.sub.C group independently represents an alkyl group or an aryl group having from 1 to 10 carbon atoms and each RD group independently represents an aryl group partially or totally fluorinated, having from 6 to 20 carbon atoms, and Pyr represents a pyrrolyl radical optionally substituted.

9. The catalytic system for the (co) polymerization of conjugated dienes comprising: at least one said oxo-nitrogenated iron complex having the general formula (I) as claimed in claim 1 wherein said element M different from carbon is selected from: boron, aluminum, zinc, magnesium, gallium, or tin.

10. A (co)polymerization process, wherein the catalytic system according to claim 1 is used to (co)polymerize conjugated dienes.

11. The (co)polymerization process according to claim 10, wherein said conjugated dienes are 1,3-butadiene or isoprene.

Description

EXAMPLES

(1) Reagents and Materials

(2) The list below reports the reagents and materials used in the following examples of the invention, any optional pre-treatments thereof and their manufacturer iron powder (Fe) (Aldrich): purity 99%, used as it is; iron trichloride (FeCl.sub.3) (Aldrich): purity 99.9%, used as it is; iron dichloride (FeCl.sub.2) (Aldrich): purity 97%, used as it is; tetrahydrofuran (THF) (Aldrich): used as it is; iron dichloride:tetrahydrofuran complex (1:1.5) [FeCl.sub.2(THF).sub.1.5] (Aldrich): prepared from iron powder (Fe) and iron trichloride (FeCl.sub.2), in tetrahydrofuran (THF) hot, according to the method specified in Calderazzo F. et al., in Comptes Rendus Acadmie des Sciences (1999), t. 2, Srie II c, pg. 311-319; iron dichloride tetrahydrate (FeCl.sub.2.4H.sub.2O) (Aldrich): purity 96%, used as it is; methylaluminoxane (MAO) (toluene solution 10% by weight) (Crompton): used as it is; 2,4-pentanedione (Aldrich): used as it is; benzene (Aldrich): pure, 99.9%, distilled over sodium (Na) in an inert atmosphere; aniline (Aldrich): distilled at reduced pressure and stored in an inert atmosphere; hydrochloric add in 37% aqueous solution (Aldrich): used as it is; o-toluidine (Aldrich): distilled at reduced pressure and stored in an inert atmosphere; p-toluidine (Aldrich): distilled at reduced pressure and stored in an inert atmosphere; 2,6-di-iso-propylaniline (Aldrich): distilled at reduced pressure and stored in an inert atmosphere; ethyl ether (Aldrich): pure, 99%, distilled over sodium (Na) in an inert atmosphere; 2,4,6-tri-methylaniline (Aldrich): distilled at reduced pressure and stored in an inert atmosphere; n-butyllithium (Aldrich): 2.5 M solution in hexane; dichloromethane (CH.sub.2Cl.sub.2) (Acres): pure, 99.9%, used as it is; Celite 545 (Aldrich): used as it is; hexane (Aldrich): pure, 99%, distilled over sodium (Na) in an inert atmosphere; heptane (Aldrich): pure, 99%, distilled over sodium (Na) in an Inert atmosphere; methanol (Carlo Erba, RPE): used as it is; toluene (Aldrich): pure, 99.5%, distilled over sodium (Na) in an inert atmosphere; 1,3-butadiene (Air Liquide): pure, 99.5%, evaporated from the container before each production, dried by passing it through a molecular sieve packed column and condensed inside the reactor that was pre-cooled to 20 C.; isoprene (Aldrich): pure, 99%, refluxed over calcium hydride for 2 hours, then distilled trap-to-trap and stored in a nitrogen atmosphere at 4 C.; hydrofluoric acid (HF) (40% aqueous solution) (Aldrich): used as it is; sulfuric acid (H.sub.2SO.sub.4) (96% aqueous solution) (Aldrich): used as it is, or diluted with distilled water (1/5); nitric add (HNO.sub.3) (70% aqueous solution) (Aldrich): used as it is; sodium carbonate (Na.sub.2CO.sub.3) (Aldrich): used as it is; silver nitrate (AgNO.sub.3) (Aldrich): used as it is; deuterated tetrachloroethylene (C.sub.2D.sub.2Cl.sub.4) (Acros): used as it is; hexamethyldisiloxane (HMDS) (Acros): used as it is; deuterated chloroform (CDCl.sub.3) (Acros): used as it is; tetramethyldisiloxane (HMDS) (Acros): used as it is;

(3) The analysis and characterization methods reported below were used.

(4) Elementary Analysis

(5) a) Determination of Fe

(6) For the determination of the quantity in weight of iron (Fe) in the oxo-nitrogenated iron complexes object of the present invention, an exactly weighted aliquot, operating in dry-box under nitrogen flow, of about 30 mg-50 mg of sample, was placed in a 30 ml platinum crucible, together with a 1 ml mixture of 40% hydrofluoric add (HF), 0.25 ml of 96% sulfuric add (H.sub.2SO.sub.4) and 1 ml of 70% nitric acid (HNO.sub.3). The crucible was then heated on a hot plate increasing the temperature until white sulfur fumes appeared (about 200 C.). The mixture thus obtained was cooled to ambient temperature (20 C.-25 C.) and 1 ml of 70% nitric add (HNO.sub.3) was added, then it was left again until fumes appeared. After repeating the sequence another two times, a clear, almost colorless, solution was obtained. 1 ml of nitric acid (HNO.sub.3) and about 15 ml of water were then added cold, then heated to 80 C. for about 30 minutes. The sample thus prepared was diluted with MilliQ pure water until it weighed about 50 g, precisely weighed, to obtain a solution on which the instrumental analytical determination was performed using a Thermo Optek IRIS Advantage Duo ICP-OES (plasma optical emission) spectrometer, for comparison with solutions of known concentration. For this purpose, for every analyte, a calibration curve was prepared in the range 0 ppm-10 ppm, measuring calibration solutions by dilution by weight of certified solutions.

(7) The solution of sample prepared as above was then diluted again by weight in order to obtain concentrations close to the reference ones, before performing spectrophotometric measurement. All the samples were prepared in double quantities. The results was considered acceptable if the individual repeated test data did not have a relative deviation of more than 2% with respect to their mean value.

(8) b) Determination of Chlorine

(9) For said purpose, samples of the oxo-nitrogenated iron complexes object of the present invention, about 30 mg-50 mg, were precisely weighed in 100 ml glass beakers in dry-box under nitrogen flow. 2 g of sodium carbonate (Na.sub.2CO.sub.3) were added and, outside the dry-box, 50 ml of MilliQ water. It was brought to the boil on the hot plate, under magnetic stirring, for about 30 minutes. It was left to cool, then 1/5 diluted sulfuric acid (H.sub.2SO.sub.4) was added, until acid reaction and was then titrated with 0.1 N silver nitrate (AgNO.sub.3) with a potentiometric titrator.

(10) c) Determination of Carbon, of Hydrogen and of Nitrogen

(11) The determination of carbon, of hydrogen and of nitrogen, in the oxo-nitrogenated iron complexes object of the present invention, like in the ligands used for the purpose of the present invention, was performed through a Carlo Erba automatic analyzer Mod. 1106.

(12) .sup.13C-HMR and .sup.1H-HMR Spectra

(13) The .sup.13C-HMR and .sup.1H-HMR spectra were recorded using a nuclear magnetic resonance spectrometer mod. Bruker Avance 400, using deuterated tetrachloroethylene (C.sub.2D.sub.2Cl.sub.4) at 103 C., and hexamethyldisiloxane (HDMS) as internal standard, or using deuterated chloroform (CDCl.sub.3), at 25 C., and tetramethylsilane (TMS) as internal standard. For this purpose, polymeric solutions were used with concentrations equal to 10% by weight with respect to the total weight of the polymeric solution.

(14) The microstructure of the polymers [i.e. 1,4-cis (%) 1,4-trans (%) and 1,2(%) unit content for polybutadiene and 1,4-cis (%), 1,4-trans (%) and 3,4(%) unit content for polyisoprene] was determined through the analysis of the aforementioned spectra based on what is reported in literature by Mochel, V. D., in Journal of Polymer Science Part A-1: Polymer Chemistry (1972), Vol. 10, Issue 4, pg. 1009-1018 for polybutadiene, and by Sato H. et al. in Journal of Polymer Science: Polymer Chemistry Edition (1979), Vol. 17, Issue 11, pg. 3551-3558, for polyisoprene.

(15) FT-IR Spectra/Solid StateUATR)

(16) The FT-IR spectra (solid stateUATR) were recorded using a Bruker IFS 48 spectrophotometer equipped with a Thermo Spectra-Tech horizontal ATR connection.

(17) The section wherein the samples to be analyzed are placed is a Fresnel ATR accessory (Shelton, Conn., USA) which uses crystals of zirconium selenide (ZnSe) with an angle of incidence of 45 in the horizontal direction.

(18) The FT-IR spectra (solid stateUATR) of the oxo-nitrogenated iron complexes object of the present invention, were obtained by inserting samples of the oxo-nitrogenated iron complex to be analyzed into said section.

(19) I.R. Spectra

(20) The I.R. (FT-IR) spectra were recorded through Thermo Nicolet Nexus 670 and Bruker IFS 48 spectrophotometers.

(21) The I.R. (FT-IR) spectra of the ligands used for the purpose of the present invention, were obtained by dispersing the ligand to be analyzed in anhydrous potassium bromide (KBr) (KBr disks), or in Nujol solution.

(22) The I.R. (FT-IR) spectra of the polymers were obtained from polymeric films on potassium bromide (KBr) tablets, said films being obtained through the deposition of a solution in hot 1,2-dichlorobenzene of the polymer to be analyzed. The concentration of the polymeric solutions analyzed was equal to 10% by weight with respect to the total weight of the polymeric solution.

(23) Determination of the Molecular Weight

(24) The determination of the molecular weight (MW) of the polymers obtained was performed through GPC (Gel Permeation Chromatography), using the Waters Alliance GPC/V 2000 System by Waters Corporation which uses two detection lines: Refractive Index (RI) and Viscometer operating under the following conditions: two PLgel Mixed-B columns; solvent/eluent: o-dichlorobenzene (Aldrich); flow rate: 0.8 ml/min; temperature: 145 C.; molecular mass calculation: Universal Calibration method.

(25) The weight-average molecular weight (M.sub.w) and the Polydispersion Index (PDI) are reported, corresponding to the ratio M.sub.w/M.sub.n (M.sub.n=number-average molecular weight).

(26) Mass Spectra

(27) The mass spectra of the ligands used for the purpose of the present invention were performed with a Trace DSQ single quadrupole mass spectrometer (Thermo ISQ) in Electronic Ionization (EI mode), operating under the following conditions: scanning: from 35 amu to 600 amu (amu=atomic mass unit); temperature of the source: 250 C.; transfer line temperature: 300 C.; capillary column: MDN-5S (Supelco) (length=30 m; diameter=0.25 mm; stationary phase thickness=0.25 m); carrier gas: helium (He) with constant flow equal to 1 ml/min.

Example 1

(28) Synthesis of Ligand Having Formula (L1)

(29) ##STR00004##

(30) 5 g (50 mmoles) of 2,4-pentandione were placed in a 500 ml flask equipped with a Dean-Stark trap for the azeotropic removal of water, together with 100 ml of benzene, some drops of hydrochloric acid and 4.66 g (50 mmoles) of aniline: the mixture obtained was heated under reflux, for 24 hours. Subsequently, the mixture was cooled to ambient temperature, filtered on a porous septum obtaining a filtrate which was evaporated under vacuum obtaining a solid product. The solid product thus obtained was dissolved in ethyl ether (40 ml) and placed in the freezer for 24 hours, obtaining a precipitate that was filtered and dried, under vacuum, at ambient temperature, obtaining 7 g of a white crystalline product (yield=80%) having formula (L1).

(31) Elementary analysis [found (calculated for C.sub.11H.sub.13NO)]: C: 75.20% (75.40%); H: 7.50% (7.48%); N: 8.00% (7.99%).

(32) Molecular weight (MW): 175.23.

(33) FT-IR (solid stateUATR) 1590 cm.sup.1; 1571 cm.sup.1.

(34) .sup.1H-NMR (CD.sub.2Cl.sub.2, ppm): 12.49 (s, 1H NH), 8.27 (d, 1H PyH), 7.34-7.28 (m, 2H ArH), 7.19-7.15 (m, 1H ArH), 7.10-7.08 (m, 2H ArH), 5.18 (s, 1H CH), 2.09 (s, 3H CH.sub.3), 1.97 (s, 3H CH.sub.3).

(35) GC-MS: M.sup.+=m/z 175.

Example 2

(36) Synthesis of Ligand Having Formula (L2)

(37) ##STR00005##

(38) 30 g (300 mmoles) of 2,4-pentandione were placed in a 500 ml flask equipped with a Dean-Stark trap for the azeotropic removal of water, together with 300 ml of benzene, some drops of hydrochloric acid and 32.1 g (300 mmoles) of o-toluidine: the mixture obtained was heated under reflux, for 24 hours. Subsequently, the mixture was cooled to ambient temperature, filtered on a porous septum obtaining a filtrate which was evaporated under vacuum obtaining a solid product. The solid product thus obtained was dissolved in ethyl ether (100 ml) and placed in the freezer for 24 hours, obtaining a precipitate that was filtered and dried, under vacuum, at ambient temperature, obtaining 35 g of a white crystalline product (yield=61%) having formula (L2).

(39) Elementary analysis [found (calculated for C.sub.12H.sub.15NO)]: C: 76.18% (76.16%); H: 7.97% (7.99%); N: 7.37% (7.40%).

(40) Molecular weight (MW): 189.26.

(41) FT-IR (solid stateUATR) 1595 cm.sup.1; 1560 cm.sup.1.

(42) .sup.1H-NMR (CD.sub.2Cl.sub.2, ppm): 1.87 (s, 3H CH.sub.3CN), 2.11 (s, 3H CH.sub.3CO), 2.28 (s, 3H C.sub.6H.sub.2CH.sub.3), 5.20 (s, 1H CH), 7.06-7.23 (s, 4H C.sub.6H.sub.4), 12.35 (s, 1H NH).

(43) GC-MS: M.sup.+=m/z 189.

Example 3

(44) Synthesis of Ligand Having Formula (L3)

(45) ##STR00006##

(46) 5 g (50 mmoles) of 2,4-pentandione were placed in a 500 ml flask equipped with a Dean-Stark trap for the azeotropic removal of water, together with 75 ml of benzene, some drops of hydrochloric add and 5.35 g (50 mmoles) of p-toluidine: the mixture obtained was heated under reflux, for 24 hours. Subsequently, the mixture was cooled to ambient temperature, filtered on a porous septum obtaining a filtrate which was evaporated under vacuum obtaining a solid product. The solid product thus obtained was dissolved in ethyl ether (10 ml) and placed in the freezer for 24 hours, obtaining a precipitate that was filtered and dried, under vacuum, at ambient temperature, obtaining 5.7 g of a white crystalline product (yield=60%) having formula (L3).

(47) Elementary analysis [found (calculated for C.sub.12H.sub.15NO)]: C: 76.13% (76.16%); H: 7.87% (7.99%); N: 7.36% (7.40%).

(48) Molecular weight (MW): 189.26.

(49) FT-IR (KBr): 1609 cm.sup.1; 1565 cm.sup.1.

(50) .sup.1H-NMR (CD.sub.2Cl.sub.2, ppm): 1.93 (s, 3H CH.sub.3), 2.05 (s, 3H CH.sub.3), 2.31 (s, 3H CH.sub.3), 5.15 (s, 1H CH), 6.98 (d, 2H Ph), 7.13 (d, 2H Ph), 12.38 (s, 1H, NH).

(51) GC-MS: M.sup.+=m/z 189.

Example 4

(52) Synthesis of Ligand Having Formula (L4)

(53) ##STR00007##

(54) 5 g (50 mmoles) of 2,4-pentandione were placed in a 500 ml flask equipped with a Dean-Stark trap for the azeotropic removal of water, together with 75 ml of benzene, some drops of hydrochloric acid and 8.9 g (50 mmoles) of 2,6-di iso-propylaniline: the mixture obtained was heated under reflux, for 24 hours. Subsequently, the mixture was cooled to ambient temperature, filtered on a porous septum obtaining a filtrate which was evaporated under vacuum obtaining a solid product. The solid product thus obtained was dissolved in ethyl ether (10 ml) and placed in the freezer for 24 hours, obtaining a precipitate that was filtered and dried, under vacuum, at ambient temperature, obtaining 6.5 g of a white crystalline product (yield=50%) having formula (L4).

(55) Elementary analysis [found (calculated for C.sub.17H.sub.23NO)]: C: 78.60% (78.72%); H: 9.60% (9.71%); N: 5.32% (5.40%).

(56) Molecular weight (MW); 259.39.

(57) FT-IR (KBr): 1606 cm.sup.1; 1567 cm.sup.1.

(58) .sup.1H NMR (CDCl.sub.3, ppm): 1.11 (d, 6H, CH(CH.sub.3).sub.2), 1.18 (d, 6H, CH(CH.sub.3).sub.2), 1.60 (s, 3H CH.sub.3CN), 2.10 (s, 3H CH.sub.3CO), 3.00 (sept 2H, CHMe.sub.2), 5.19 (s, 1H CHCO), 7.12-7.28 (m, 3H, Ar), 12.05 (s, 1H NH).

(59) GC-MS: M.sup.+=m/z 259.

Example 5

(60) Synthesis of Ligand Having Formula (L5)

(61) ##STR00008##

(62) 5 g (50 mmoles) of 2,4-pentandione were placed in a 500 ml flask equipped with a Dean-Stark trap for the azeotropic removal of water, together with 75 ml of benzene, some drops of hydrochloric acid and 6.76 g (50 mmoles) of 2,4,6-tri-methylaniline: the mixture obtained was heated under reflux, for 24 hours. Subsequently, the mixture was cooled to ambient temperature, filtered on a porous septum obtaining a filtrate which was evaporated under vacuum obtaining a solid product. The solid product thus obtained was dissolved in ethyl ether (10 ml) and placed in the freezer for 24 hours, obtaining a precipitate that was filtered and dried, under vacuum, at ambient temperature, obtaining 4.8 g of a light yellow product (yield=44%) having formula (L5).

(63) Elementary analysis [found (calculated for C.sub.14H.sub.19NO)]: C: 77.40% (77.38%); H: 9.00% (8.81%); N: 6.32% (6.45%).

(64) Molecular weight (MW): 217.31.

(65) FT-IR (solid state, ATR): 1606 cm.sup.1; 1567 cm.sup.1.

(66) .sup.1H-NMR (CD.sub.2Cl.sub.2, ppm): 1.6 (s, 3H CH.sub.3CN), 2.05 (s, 3H CH.sub.3CO), 2.18 (s, 6H 2-C.sub.6H.sub.2CH.sub.3), 2.28 (s, 3H 4-C.sub.6H.sub.2CH.sub.3), 5.21 (s, 1H CH), 6.92 (s, 2H CM), 11.82 (s, 1H NH).

(67) GC-MS: M.sup.+=m/z 217.

Example 6

(68) Synthesis of FeCl.sub.2(L1) [Sample MG101]

(69) ##STR00009##

(70) In a 100 ml flask, a solution of n-butyllithium (2.5 M in hexane; 0.6 ml; 1.43 mmoles) was added to a solution of the ligand having formula (L1) (250 mg; 1.43 mmoles), obtained as described in Example 1, in hexane (40 ml), maintained at 40 C.: the solution obtained was left to return to ambient temperature slowly and maintained at said temperature, under stirring, for about 4 hours. Subsequently, iron trichloride (FeCl.sub.3) (232 mg; 1.43 mmoles; molar ratio L1/Fe=1) was added: the brown suspension obtained was left, under stirring, at ambient temperature, for about 5 hours. The solvent was then removed under vacuum, at ambient temperature, and the residue obtained was suspended in dichloromethane (CH.sub.2Cl.sub.2) (20 ml). The suspension obtained was filtered on Celite 545 and the solution obtained was dried, under vacuum, at ambient temperature, obtaining 275 mg of a dark brown solid product corresponding to the complex FeCl.sub.2(L1), equal to a 64% conversion with respect to the iron trichloride (FeCl.sub.3) loaded.

(71) Elementary analysis [found (calculated for C.sub.11H.sub.12Cl.sub.2FeNO)]: C: 43.45% (43.89%); H: 4.31% (4.02%); N: 4.48% (4.65%); Cl: 22.99% (23.56%); Fe: 17.95% (18.55%).

(72) FIG. 1 shows the FT-IR spectrum (solid stateUATR) of the complex FeCl.sub.2(L1) obtained.

Example 7

(73) Synthesis of FeCl.sub.2(L1).sub.2 [Sample MG110]

(74) ##STR00010##

(75) In a 100 ml flask, the iron dichloride:tetrahydrofuran complex (1:1.5) [FeCl.sub.2(THF).sub.1.5] (237 mg; 1.01 mmoles; molar ratio L1/Fe=2) was added to a solution of the ligand having formula (L1) (353 mg; 2.02 mmoles), obtained as described in Example 1, in tetrahydrofuran (THF) (40 ml): the intense orange mixture obtained was maintained, under stirring, at ambient temperature, for 3 hours. The solvent was then removed under vacuum and the residue obtained was dried under vacuum, at ambient temperature, obtaining 450 mg of an orange solid product corresponding to the complex FeCl.sub.2(L1).sub.2, equal to a 93% conversion with respect to the iron dichloride:tetrahydrofuran complex (1:1.5) [FeCl.sub.2(THF).sub.1.5] loaded.

(76) Elementary analysis [found (calculated for C.sub.22H.sub.26Cl.sub.2FeN.sub.2O.sub.2)]: C: 55.95% (55.37%); H: 5.01% (5.49%); N: 5.48% (5.87%); Cl: 15.01% (14.85%); Fe: 11.25% (11.70%).

(77) FIG. 2 shows the FT-IR spectrum (solid stateUATR) of the complex FeCl.sub.2(L1).sub.2 obtained.

Example 8

(78) Synthesis of FeCl.sub.2(L2) [Sample MG199]

(79) ##STR00011##

(80) In a 100 ml flask, a solution of n-butyllithium (2.5 M in hexane; 0.46 ml; 1.14 mmoles) was added to a solution of the ligand having formula (L2) (215 mg; 1.14 mmoles), obtained as described in Example 2, in hexane (30 ml), maintained at 40 C.: the solution obtained was left to return to ambient temperature slowly and maintained at said temperature, under stirring, for about 4 hours. Subsequently, iron trichloride (FeCl.sub.2) (185 mg; 1.14 mmoles; molar ratio L2/Fe=1) was added: the brown suspension obtained was left, under stirring, at ambient temperature, for about 5 hours. The solvent was then removed under vacuum, at ambient temperature, and the residue obtained was suspended in dichloromethane (CH.sub.2Cl.sub.2) (20 ml). The suspension obtained was filtered on Celite 545 and the solution obtained was dried, under vacuum, at ambient temperature, obtaining 224 mg of a purple solid product corresponding to the complex FeCl.sub.2(L2), equal to a 62% conversion with respect to the iron trichloride (FeCl.sub.3) loaded.

(81) Elementary analysis [found (calculated for C.sub.12H.sub.14Cl.sub.2FeNO)]: C: 45.05% (45.75%); H: 4.03% (4.46%); N: 4.12% (4.45%); Cl: 22.00% (22.51%); Fe: 17.54% (17.73%).

(82) FIG. 3 shows the FT-IR spectrum (solid stateUATR) of the complex FeCl.sub.2(L2) obtained.

Example 9

(83) Synthesis of FeCl.sub.2(L2).sub.2 [Sample MG114]

(84) ##STR00012##

(85) In a 100 ml flask, iron dichloride tetrahydrate (FeCl.sub.2.4H.sub.2O) (638 mg; 3.38 mmoles; molar ratio L2/Fe=2) was added to a solution of the ligand having formula (L2) (353 mg; 2.02 mmoles), obtained as described in Example 2, in tetrahydrofuran (THF) (40 ml): the intense orange mixture obtained was maintained, under stirring, at ambient temperature, for 3 hours. The solvent was then removed under vacuum and the residue obtained was dried under vacuum, at ambient temperature, obtaining 700 mg of an orange solid product corresponding to the complex FeCl.sub.2(L2).sub.2, equal to a 93% conversion with respect to the iron dichloride tetrahydrate (FeCl.sub.2.4H.sub.2O) loaded.

(86) Elementary analysis [found (calculated for C.sub.24H.sub.30Cl.sub.2FeN.sub.2O.sub.2)]: C: 56.95% (57.05%); H: 5.51% (5.98%); N: 5.48% (5.54%); Cl: 14.51% (14.03%); Fe: 11.95% (11.05%).

(87) FIG. 4 shows the FT-IR spectrum (solid stateUATR) of the complex FeCl.sub.2(L2).sub.2 obtained.

Example 10

(88) Synthesis of FeCl.sub.2(L3) [Sample MG200]

(89) ##STR00013##

(90) In a 100 ml flask, a solution of n-butyllithium (2.5 M In hexane; 0.44 ml; 1.10 mmoles) was added to a solution of the ligand having formula (L3) (208 mg; 1.10 mmoles), obtained as described in Example 3, in hexane (30 ml), maintained at 40 C.: the solution obtained was left to return to ambient temperature slowly and maintained at said temperature, under stirring, for about 4 hours. Subsequently, iron trichloride (FeCl.sub.3) (179 mg; 1.10 mmoles; molar ratio L3/Fe=1) was added: the brown suspension obtained was left, under stirring, at ambient temperature, for about 5 hours. The solvent was then removed under vacuum, at ambient temperature, and the residue obtained was suspended in dichloromethane (CH.sub.2Cl.sub.2) (20 ml). The suspension obtained was filtered on Celite 545 and the solution obtained was dried, under vacuum, at ambient temperature, obtaining 184 mg of a purple solid product corresponding to the complex FeCl.sub.2(L3), equal to a 53% conversion with respect to the iron trichloride (FeCl.sub.3) loaded.

(91) Elementary analysis [found (calculated for C.sub.12H.sub.14Cl.sub.2FeNO)]: C: 44.99% (45.75%); H: 4.31% (4.48%); N: 4.56% (4.45%); Cl: 22.20% (22.51%); Fe: 18.05% (17.73%).

(92) FIG. 5 shows the FT-IR spectrum (solid stateUATR) of the complex FeCl.sub.2(L3) obtained.

Example 11

(93) Synthesis of FeCl.sub.2(L3).sub.2 [Sample MG137

(94) ##STR00014##

(95) In a 100 ml flask, the iron dichloride:tetrahydrofuran complex (1:1.5) [FeCl.sub.2(THF).sub.1.5] (94 mg; 0.36 mmoles; molar ratio L3/Fe=2) was added to a solution of the ligand having formula (L3) (135 mg; 0.71 mmoles), obtained as described in Example 3, in tetrahydrofuran (THF) (20 ml): the intense orange mixture obtained was maintained, under stirring, at ambient temperature, for 3 hours. The solvent was then removed under vacuum and the residue obtained was washed with heptane (210 ml) and dried under vacuum, at ambient temperature, obtaining 161 mg of an orange solid product corresponding to the complex FeCl.sub.2(L3).sub.2, equal to an 89% conversion with respect to the iron dichloride:tetrahydrofuran complex (1:1.5) [FeCl.sub.2(THF).sub.1.5] loaded.

(96) Elementary analysis [found (calculated for C.sub.24H.sub.30Cl.sub.2FeN.sub.2O.sub.2)]: C: 56.75% (57.05%); H: 5.61% (5.98%); N: 5.75% (5.54%); Cl: 14.81% (14.03%); Fe: 11.55% (11.05%).

(97) FIG. 6 shows the FT-IR spectrum (solid stateUATR) of the complex FeCl.sub.2(L3).sub.2 obtained.

Example 12

(98) Synthesis of FeCl.sub.2(L4) [Sample MG201]

(99) ##STR00015##

(100) In a 100 ml flask, a solution of n-butyllithium (2.5 M In hexane; 0.28 ml; 0.69 mmoles) was added to a solution of the ligand having formula (L4) (180 mg; 0.69 mmoles), obtained as described in Example 4, in hexane (15 ml), maintained at 40 C.: the solution obtained was left to return to ambient temperature slowly and maintained at said temperature, under stirring, for about 4 hours. Subsequently, iron trichloride (FeCl.sub.2) (113 mg; 0.69 mmoles; molar ratio L4/Fe=1) was added: the brown suspension obtained was left, under stirring, at ambient temperature, for about 5 hours. The solvent was then removed under vacuum, at ambient temperature, and the residue obtained was suspended in dichloromethane (CH.sub.2Cl.sub.2) (20 ml). The suspension obtained was filtered on Celite 545 and the solution obtained was dried, under vacuum, at ambient temperature, obtaining 205 mg of a purple solid product corresponding to the complex FeCl.sub.2(L4), equal to a 77% conversion with respect to the iron trichloride (FeCl.sub.2) loaded.

(101) Elementary analysis [found (calculated for C.sub.17H.sub.24Cl.sub.2FeNO)]: C: 52.56% (53.02%); H: 6.00% (6.28%); N: 3.01% (3.64%); Cl: 17.99% (18.41%); Fe: 15.01% (14.50%).

(102) FIG. 7 shows the FT-IR spectrum (sold stateUATR) of the complex FeCl.sub.2(L4) obtained.

Example 13

(103) Synthesis of FeCl.sub.2(L4).sub.2 [Sample MG145]

(104) ##STR00016##

(105) In a 100 ml flask, the iron dichloride:tetrahydrofuran complex (1:1.5) [FeCl.sub.2(THF).sub.1.5] (134 mg; 0.57 mmoles; molar ratio L4/Fe=2) was added to a solution of the ligand having formula (L4) (296 mg; 1.14 mmoles), obtained as described in Example 4, in tetrahydrofuran (THF) (20 ml): the intense orange mixture obtained was maintained, under stirring, at ambient temperature, for 3 hours. The solvent was then removed under vacuum and the residue obtained was washed with heptane (210 ml) and dried under vacuum, at ambient temperature, obtaining 292 mg of an orange solid product corresponding to the complex FeCl.sub.2(L4).sub.2, equal to a 79% conversion with respect to the iron dichloride:tetrahydrofuran complex (1:1.5) [FeCl.sub.2(THF).sub.1.5] loaded.

(106) Elementary analysis [found (calculated for C.sub.34H.sub.50Cl.sub.2FeN.sub.2O.sub.2)]: C: 63.75% (63.26%); H: 7.61% (7.81%); N: 4.75% (4.34%); Cl: 10.21% (10.98%); Fe: 8.15% (8.65%).

(107) FIG. 8 shows the FT-IR spectrum (solid stateUATR) of the complex FeCl.sub.2(L4).sub.2 obtained.

Example 14

(108) Synthesis of FeCl.sub.2(L5) [Sample MG102]

(109) ##STR00017##

(110) In a 100 ml flask, a solution of n-butyllithium (2.5 M In hexane; 0.55 ml; 1.37 mmoles) was added to a solution of the ligand having formula (L5) (298 mg; 1.37 mmoles), obtained as described in Example 5, in hexane (40 ml), maintained at 40 C.: the solution obtained was left to return to ambient temperature slowly and maintained at said temperature, under stirring, for about 4 hours. Subsequently, iron trichloride (FeCl.sub.3) (223 mg; 1.37 mmoles; molar ratio L5/Fe=1) was added: the brown suspension obtained was left, under stirring, at ambient temperature, for about 5 hours. The solvent was then removed under vacuum, at ambient temperature, and the residue obtained was suspended in dichloromethane (CH.sub.2Cl.sub.2) (20 ml). The suspension obtained was filtered on Celite 545 and the solution obtained was dried, under vacuum, at ambient temperature, obtaining 383 mg of a purple solid product corresponding to the complex FeCl.sub.2(L5), equal to a 74% conversion with respect to the iron trichloride (FeCl.sub.3) loaded.

(111) Elementary analysis [found (calculated for C.sub.14H.sub.18Cl.sub.2FeNO)]: C: 49.75% (49.02%); H: 5.61% (5.29%); N: 4.43% (4.08%); Cl: 20.21% (20.67%); Fe: 15.85% (16.28%).

(112) FIG. 9 shows the FT-IR spectrum (solid stateUATR) of the complex FeCl.sub.2(L5) obtained.

Example 15

(113) Synthesis of FeCl.sub.2(L5).sub.2 [Sample MG112]

(114) ##STR00018##

(115) In a 100 ml flask, the iron dichloride:tetrahydrofuran complex (1:1.5) [FeCl.sub.2(THF).sub.1.5] (309 mg; 1.32 mmoles; molar ratio L5/Fe=2) was added to a solution of the ligand having formula (L5) (571 mg; 2.64 mmoles), obtained as described in Example 5, in tetrahydrofuran (THF) (40 ml): the intense orange mixture obtained was maintained, under stirring, at ambient temperature, for 3 hours. The solvent was then removed under vacuum and the residue obtained was washed with heptane (210 ml) and dried under vacuum, at ambient temperature, obtaining 651 mg of an orange solid product corresponding to the complex FeCl.sub.2(L5).sub.2, equal to an 88% conversion with respect to the iron dichloride:tetrahydrofuran complex (1:1.5) [FeCl.sub.2(THF).sub.1.5] loaded.

(116) Elementary analysis [found (calculated for C.sub.28H.sub.38Cl.sub.2FeN.sub.2O.sub.2)]: C: 59.25% (59.91%); H: 6.61% (6.82%); N: 4.78% (4.99%); Cl: 12.21% (12.63%); Fe: 9.25% (9.95%).

(117) FIG. 10 shows the FT-IR spectrum (solid stateUATR) of the complex FeCl.sub.2(L5).sub.2 obtained.

Example 16 (G1470)

(118) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 8.2 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) in toluene solution (6.3 ml; 110.sup.2 motes, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L1) complex [sample MG101] (1.5 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 3.01 mg) obtained as described in Example 6. The whole was kept under magnetic stirring, at ambient temperature, for 3 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.754 g of polybutadiene having a mixed 1,4-cis/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(119) FIG. 11 shows the FT-IR spectrum of the polybutadiene obtained.

(120) FIG. 12 shows the GPC (Gel Permeation Chromatography) curve of the polybutadiene obtained.

(121) FIG. 13 shows the .sup.1H-NMR (top) and .sup.13C-NMR (bottom) spectra of the polybutadiene obtained.

Example 17 (G1471)

(122) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 7.3 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) in toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L1).sub.2 complex [sample MG110] (2.4 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.8 mg) obtained as described in Example 7. The whole was kept under magnetic stirring, at ambient temperature, for 3 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric add. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 1.4 g of polybutadiene having a mixed 1,4-cis/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(123) FIG. 14 shows the FT-IR spectrum of the polybutadiene obtained.

(124) FIG. 15 shows the GPC (Gel Permeation Chromatograph) curve of the polybutadiene obtained.

(125) FIG. 16 shows the .sup.1H-NMR (top) and .sup.13C-NMR (bottom) spectra of the polybutadiene obtained.

Example 18 (G1474)

(126) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 10.45 ml of toluene were added and the temperature of the solution thus obtained was brought to 50 C. Then, methylaluminoxane (MAO) in toluene solution (3.15 ml; 510.sup.3 moles, equal to about 0.29 g) was added and, subsequently, the FeCl.sub.2(L1).sub.2 complex [sample MG110] (2.4 ml of toluene solution at a concentration equal 2 mg/ml; 110.sup.5 moles, equal to about 4.6 mg) obtained as described in Example 7. The whole was kept under magnetic stirring, at 50 C., for 120 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.456 g of polybutadiene having a mixed 1,4-cis/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(127) FIG. 17 shows the FT-IR spectrum of the polybutadiene obtained.

Example 19 (IP185)

(128) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 8.1 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) in toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L2) complex [sample MG199] (1.6 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 3.15 mg) obtained as described in Example 8. The whole was kept under magnetic stirring, at ambient temperature, for 120 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.580 g of polybutadiene having a mixed 1,4-cis/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(129) FIG. 18 shows the FT-IR spectrum of the polybutadiene obtained.

Example 20 (IP180)

(130) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 7.2 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) in toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L2).sub.2 complex [sample MG114] (2.5 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.05 mg) obtained as described in Example 9. The whole was kept under magnetic stirring, at ambient temperature, for 120 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric add. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 1.028 g of polybutadiene having a mixed 1,4-cis/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

Example 21 (IP186)

(131) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 8.1 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) In toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L3) complex [sample MG101] (1.6 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.6 moles, equal to about 3.15 mg) obtained as described in Example 10. The whole was kept under magnetic stirring, at ambient temperature, for 120 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.438 g of polybutadiene having a mixed 1,4-cis/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(132) FIG. 19 shows the FT-IR spectrum of the polybutadiene obtained.

Example 22 (IP140)

(133) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 7.2 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) in toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L3).sub.2 complex [sample MG137] (2.5 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.05 mg) obtained as described in Example 11. The whole was kept under magnetic stirring, at ambient temperature, for 480 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric add. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.262 g of polybutadiene having a mixed 1,4-cis/1,4-trans/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(134) FIG. 20 shows the FT-IR spectrum of the polybutadiene obtained.

(135) FIG. 21 shows the .sup.1H-NMR (top) and .sup.13C-NMR (bottom) spectra of the polybutadiene obtained.

Example 23 (IP184)

(136) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 7.8 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) In toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L4) complex [sample MG201] (1.9 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 3.85 mg) obtained as described in Example 12. The whole was kept under magnetic stirring, at ambient temperature, for 5760 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.331 g of polybutadiene having a mixed 1,4-cis/1,4-trans/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(137) FIG. 22 shows the FT-IR spectrum of the polybutadiene obtained.

Example 24 (IP141)

(138) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 6.5 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) In toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L4).sub.2 complex [sample MG145] (3.2 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 6.46 mg) obtained as described in Example 13. The whole was kept under magnetic stirring, at ambient temperature, for 180 minutes.

(139) The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric add. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.561 g of polybutadiene having a mixed 1,4-cis/1,4-trans/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(140) FIG. 23 shows the FT-IR spectrum of the polybutadiene obtained.

(141) FIG. 24 shows the GPC (Gel Permeation Chromatography) curve of the polybutadiene obtained.

Example 25 (G1472)

(142) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 7.98 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) in toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L5) complex [sample MG102] (1.72 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 3.43 mg) obtained as described in Example 14. The whole was kept under magnetic stirring, at ambient temperature, for 5760 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric add. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.290 g of polybutadiene having a mixed 1,4-cis/1,4-trans/1,2 structure. Further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(143) FIG. 25 shows the FT-IR spectrum of the polybutadiene obtained.

Example 26 (G1473)

(144) 2 ml of 1,3-butadiene equal to about 1.4 g were condensed, cold (20 C.) in a 25 ml test tube. Subsequently, 6.89 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane (MAO) in toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L5).sub.2 complex [sample MG112] (2.8 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.6 mg) obtained as described in Example 15. The whole was kept under magnetic stirring, at ambient temperature, for 390 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.417 g of polybutadiene having a mixed 1,4-cis/1,2 structure: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(145) FIG. 26 shows the FT-IR spectrum of the polybutadiene obtained.

(146) FIG. 27 shows the .sup.1H-NMR (top) and .sup.13C-NMR (bottom) spectra of the polybutadiene obtained.

Example 27 (IP126)

(147) 7.3 ml of toluene were inserted into a 25 ml test tube and, subsequently, 2 ml of isoprene equal to about 1.36 g. Then methylaluminoxane (MAO) in toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L1).sub.2 complex [sample MG110] (2.48 ml of toluene solution at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.8 mg) obtained as described in Example 7. The whole was kept under magnetic stirring, at ambient temperature, for 180 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric add. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.553 g of polyisoprene having a mixed 1,4-cis/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 2.

(148) FIG. 28 shows the FT-IR spectrum of the polyisoprene obtained.

Example 28 (IP143)

(149) 6.5 ml of toluene were inserted into a 25 ml test tube, at ambient temperature, and, subsequently, 2 ml of isoprene equal to about 1.36 g. Then methylaluminoxane (MAO) in toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, subsequently, the FeCl.sub.2(L4).sub.2 complex [sample MG145] (3.2 ml of toluene at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 6.4 mg) obtained as described in Example 13. The whole was kept under magnetic stirring, at ambient temperature, for 600 minutes. The polymerization was then stopped by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 antioxidant (Ciba) obtaining 0.502 g of polyisoprene having a mixed 1,4-cis/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 2.

(150) FIG. 29 shows the FT-IR spectrum of the polyisoprene obtained.

(151) TABLE-US-00001 TABLE 1 Polymerization of 1,3-butadiene with catalytic systems comprising iron complexes Time Conversion 1,4-cis 1,4-trans 1.2 M.sub.w Example (min) (%) (%) (%) (%) (gxmol.sup.1) M.sub.w/M.sub.n 16 3 53.9 46.6 0 53.4 575000 2.0 17 3 100 44.3 0 55.7 402000 1.9 18 120 32.1 47.5 0 52.5 818000 2.1 19 120 41.4 46.1 0 53.9 560500 2.1 20 120 73.4 49.7 0 50.3 455000 1.8 21 1210 31.3 53.5 0 46.5 492000 2.0 22 480 18.7 51.6 4 44.4 344000 1.9 23 5760 23.6 75.7 4.9 19.4 297500 2.2 24 180 40.1 81.0 6.9 12.1 154500 2.1 25 5760 20.7 80.6 7.1 12.3 283000 2.2 26 390 29.8 80.1 0 19.9 164500 2.1

(152) TABLE-US-00002 TABLE 2 Polymerization of isoprene with catalytic systems comprising iron complexes Time Conversion 1,4-cis 1,4-trans 3.4 M.sub.w Example (min) (%) (%) (%) (%) (gxmol.sup.1) M.sub.w/M.sub.n 27 180 40.7 39.4 0 60.6 175000 2.0 28 600 36.9 33.5 0 66.5 97500 1.9