Process for the preparation of (co)polymers of conjugated dienes in the presence of a catalytic system comprising a vanadium bis-imine complex

Abstract

Process for the preparation of (co) polymers of conjugated dienes comprising polymerizing at least one conjugated diene in the presence of a catalytic system comprising at least one vanadium bis-imine complex having the general formula (I): wherein: m is 0 or 1; Z represents a CR.sub.5R.sub.6 group wherein R.sub.5 and R.sub.6, equal to or different from each other, represent a hydrogen atom; or a C.sub.1-C.sub.20 alkyl group, preferably C.sub.1-C.sub.15, linear or branched; or a bivalent aromatic group optionally substituted; R.sub.1 and R.sub.2 equal to or different from each other, represent a hydrogen atom; or they are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, optionally halogenated, cycloalkyl groups optionally substituted; or R.sub.1 and R.sub.2, may be optionally bound each other so as to form, together with the other atoms which they are bound to, a cycle containing from 4 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted by C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, said cycle optionally containing heteroatoms such as, for example, oxygen, sulfur, nitrogen, silicon, phosphorus, selenium; R.sub.3 and R.sub.4, equal to or different from each other, represent a hydrogen atom; or they are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; or R.sub.2 and R.sub.4, may be optionally bound each other so as to form, together with the other atoms which they are bound to, a cycle containing from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted by C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, said cycle optionally containing other heteroatoms such as, for example, oxygen, sulfur, nitrogen, silicon, phosphorus, selenium; or R.sub.1 and R.sub.3, may be optionally bound each other so as to form, together with other atoms which they are bound to, a cycle containing from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted by C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.1, linear or branched, said cycle optionally containing other heteroatoms such as oxygen, sulfur, nitrogen, silicon, phosphorus, selenium; X.sub.1, X.sub.2 and X.sub.3, equal to or different from each other, represent a halogen atom such as, for example, chlorine, bromine, iodine, preferably chlorine; or they are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, OCOR.sub.7 groups or OR.sub.7 groups wherein R.sub.7 is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched; Y is selected from ethers such as, for example, diethylether, tetrahydrofuran (THF), dimethoxyethane, preferably is tetrahydrofuran (THF); n is 0 or 1. ##STR00001##

Claims

1. A process for preparing a (co)polymer of conjugated dienes, comprising polymerizing at least one conjugated diene in the presence of a catalytic system comprising at least one vanadium bis-imine complex having formula (I): ##STR00021## wherein: m is 0 or 1; Z represents a CR.sub.5R.sub.6 group wherein R.sub.5 and R.sub.6 independently represent a hydrogen atom; or a C.sub.1-C.sub.20 alkyl group, linear or branched; or a bivalent aromatic group optionally substituted; R.sub.1 and R.sub.2 are independently selected from the group consisting of a hydrogen atom, a C.sub.1-C.sub.20 alkyl group, linear or branched, optionally halogenated, and a cycloalkyl group optionally substituted; or R.sub.1 and R.sub.2, optionally bound to each other so as to form, together with the other atoms which they are bound to, a cycle comprising from 4 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted by one or more C.sub.1-C.sub.20 alkyl groups, linear or branched, said cycle optionally comprising one or more heteroatoms; R.sub.3 and R.sub.4 are independently selected from the group consisting of a hydrogen atom, a C.sub.1-C.sub.20 alkyl group, linear or branched, optionally halogenated, a cycloalkyl group optionally substituted, and an aryl group optionally substituted; or R.sub.2 and R.sub.4 optionally bound to each other so as to form, together with the other atoms which they are bound to, a cycle comprising from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted by one or more C.sub.1-C.sub.20 alkyl groups, linear or branched, said cycle optionally comprising one or more heteroatoms; or R.sub.1 and R.sub.3 optionally bound to each other so as to form, together with other atoms which they are bound to, a cycle comprising from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted by one or more C.sub.1-C.sub.20 alkyl groups, linear or branched, said cycle optionally comprising one or more heteroatoms; X.sub.1, X.sub.2 and X.sub.3 are independently selected from the group consisting of a halogen atom, a C.sub.1-C.sub.20 alkyl group, linear or branched, an OCOR.sub.7 group, and an OR.sub.7 group wherein R.sub.7 is a C.sub.1-C.sub.20 alkyl group, linear or branched; Y is an ether; and n is 0 or 1.

2. The process of claim 1, wherein said catalytic system comprises at least one co-catalyst (b), which is an organic compound of an M element different from carbon, said M element being selected from the group consisting of elements belonging to the groups 2, 12, 13 and 14 of the Periodic Table of the Elements.

3. The process of claim 2, wherein said co-catalyst (b) is (b.sub.1) an aluminum alkyl having formula (II):
Al(X).sub.n(R.sub.8).sub.3-n(II) wherein X represents a halogen atom; R.sub.8 is selected from the group consisting of a linear or branched C.sub.1-C.sub.20 alkyl group, a cycloalkyl group, and an aryl group, said groups being optionally substituted by one or more silicon or germanium atoms; and n is an integer ranging from 0 to 2.

4. The process of claim 2, wherein said co-catalyst (b) comprises (b.sub.2) an organo-oxygenated compound of an M element different from carbon, said M element belonging to the groups 13 and 14 of the Periodic Table of the Elements.

5. The process of claim 2, wherein said co-catalyst (b) comprises (b.sub.3) a compound or mixture of organo-metallic compounds of an M element different from carbon, which is capable of reacting with the vanadium bis-imine complex having formula (I) and extracting from the vanadium bis-imine complex having formula (I) a X.sub.1, X.sub.2 or X.sub.3 substituent -bound, to form on one hand at least one neutral compound, and on the other hand an ionic compound consisting of a cation comprising the metal (V) coordinated by the ligand, and from a non-coordinating organic anion comprising the M metal, whose negative charge is delocalized on a multicenter structure.

6. The process of claim 1, wherein said conjugated diene is at least one selected from the group consisting of: 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and cyclo-1,3-hexadiene.

7. The process of claim 1, wherein in said vanadium bis-imine complex having formula (I): m is 0; R.sub.1 and R.sub.2 are independently selected from the group consisting of a hydrogen atom and a linear or branched C.sub.1-C.sub.20 alkyl group; R.sub.3 and R.sub.4 are independently a phenyl group optionally substituted by one or more linear or branched C.sub.1-C.sub.20 alkyl groups; X.sub.1, X.sub.2 and X.sub.3 are independently a halogen atom; n is 0 or 1; and Y is tetrahydrofuran (THF).

8. The process of claim 3, wherein said aluminum alkyl (b.sub.1) having formula (II) is di-ethyl-aluminum chloride (DEAC), mono-ethyl-aluminum dichloride (EADC), or ethylaluminumsesquichloride (EASC).

9. The process of claim 4, wherein said organo-oxygenated compound (b.sub.2) is one or more aluminoxanes having formula (III):
(R.sub.9).sub.2AlO[Al(R.sub.10)O].sub.pAl(R.sub.11).sub.2(III) wherein R.sub.9, R.sub.10 and R.sub.11 are independently selected from the group consisting of a hydrogen atom, a halogen atom, a linear or branched C.sub.1-C.sub.20 alkyl group, a cycloalkyl group, and an aryl group, said groups being optionally substituted by one or more silicon or germanium atoms; and p is an integer ranging from 0 to 1000.

10. The process of claim 9, wherein said organo-oxygenated compound (b.sub.2) is methylaluminoxane (MAO).

11. The process of claim 5, wherein said compound or mixture of compounds (b.sub.3) is an organic compound of aluminum or boron.

12. The process of claim 1, wherein said process is carried out in the presence of at least one inert organic solvent selected from the group consisting of: a saturated aliphatic hydrocarbon; a saturated cyclo-aliphatic hydrocarbon; a mono-olefin; an aromatic hydrocarbon; and a halogenated hydrocarbon.

13. The process of claim 12, wherein a concentration of the conjugated diene to be (co)polymerized in said inert organic solvent is from 5% by weight to 50% by weight, with respect to a total weight of the conjugated diene and the inert organic solvent.

14. The process of claim 1, wherein said process is carried out at a temperature ranging from 70 C. to +100 C.

Description

EXAMPLES

(1) Reagents and Materials

(2) The reagents and materials used in the following examples of the invention, the optional pretreatments thereof and the manufacturer thereof, are reported in the list below: vanadium trichloride:tetrahydrofuran complex (1:3) [VCl.sub.3(THF).sub.3] (Aldrich): purity degree 97%, used as such; methylaluminoxane (MAO) (toluene solution 10% by weight) (Crompton): used as such; or in the dry form (MAO-dry) obtained by removing the free trimethylaluminum together with the solvent from the toluene solution under vacuum and drying the residue obtained always under vacuum; modified methylaluminoxane (MAO-modified) (7% toluene solution) (Akzo Nobel): used as such; aniline (Aldrich): used after purification by means of distillation; 2 tert-butylaniline (Aldrich): used as such; 2,6-di-iso-propylaniline (Aldrich): used as such; o-toluidine (Aldrich): used as such; 2,4,6-trimethylaniline (Aldrich): used as such; methanol (Carlo Erba, RPE): used as such, or optionally anhydrified by distillation on magnesium (Mg); formic acid (Aldrich): used as such; 2,3-butandione (Aldrich): used as such; glyoxal (40% aqueous solution) (Aldrich): used as such; acetic acid (Aldrich): used as such; pentane (Fluka): purity degree 99%, maintained at reflux on sodium/potassium (Na/K) for about 8 hours, then distilled and stored on molecular sieves under nitrogen; toluene (Fluka): purity degree >99.5%, maintained under reflux on sodium (Na) for about 8 hours, then distilled and stored on molecular sieves under nitrogen; 1,2-dichlorobenzene (Aldrich): purity degree 99%, maintained at reflux on calcium hydride (CaH.sub.2) for about 8 hours, then distilled trap-to-trap and maintained in nitrogen atmosphere at 4 C.; 1,3-butadiene (Air Liquide): pure, 99.5%, evaporated from the container before of each production, dried by passing through a column packed with molecular sieves and condensed into the reactor which was pre-cooled at 20 C.; isoprene (Aldrich): pure, 99%, maintained at reflux on calcium hydride for 2 hours, then distilled trap-to-trap and maintained in nitrogen atmosphere at 4 C.; fluorhydric acid (HF) (40% aqueous solution) (Aldrich): used as such; sulfuric acid (H.sub.2SO.sub.4) (96% aqueous solution) (Aldrich): used as such, or diluted with distilled water (1/5); nitric acid (HNO.sub.3) (70% aqueous solution) (Aldrich): used as such; sodium carbonate (Na.sub.2CO.sub.3) (Aldrich): used as such; silver nitrate (AgNO.sub.3) (Aldrich): used as such; tetrachloroethane deuterated (C.sub.2D.sub.2Cl.sub.4) (Acros): used as such; examethyldisiloxane (HMDS) (Acros): used as such.

(3) Analysis and characterization methods, reported below, were used.

(4) Elementary Analysis

(5) a) Determination of V

(6) For determining the weight amount of vanadium (V), in the vanadium bis-imine complexes used for the aim of the present invention, an aliquot exactly weighted, operating in dry-box under nitrogen flux, of about 30 mg-50 mg of sample, was placed in a platinum crucible of about 30 ml, together with a mixture of 1 ml of hydrofluoric acid (HF) at 40%, 0.25 ml of sulphuric acid (H.sub.2SO.sub.4) at 96% and 1 ml of nitric acid (HNO.sub.3) at 70%. The crucible were then heated on a plate increasing the temperature up to the appearance of sulphuric white fumes (about 200 C.). The mixture thus obtained was cooled at room temperature (20 C.-25 C.) additivated with 1 ml of nitric acid (HNO.sub.3) at 70% and then brought again to fumes appearance. After having repeated for other two times the sequence, a clear solution, almost without colour, was obtained. Then, 1 ml of nitric acid (HNO.sub.3) and about 15 ml of water, were added, in the cold, then heated to 80 C., for about 30 minutes. The sample thus prepared was diluted with pure water MilliQ up to a weight of about 50 g, exactly weighted, to obtain a solution on which the instrumental analytic determination was carried out by a ICP-OES spectrometer (optical detection plasma) Thermo Optek IRIS Advantage Duo, by comparison with solutions having known concentration. For this aim, for each analyte, a calibration line was prepared in the range 0 ppm-10 ppm, measuring solutions with known titer obtained by dilution per weighing of certified solutions.

(7) The solution of the sample prepared as above was further diluted by weighing so as to obtain concentrations close to those of reference, before carrying out the spectrophotometric detection. All the samples were prepared in duplicate. The results were considered acceptable if the single data of the duplicate tests did not differ more than relative 2% with respect to the average value thereof.

(8) b) Determination of Chlorine

(9) About that, the samples of the vanadium bis-imine complexes used for the aim of the present invention, about 30 mg-50 mg, were exactly weighted into 100 ml glass in dry-box under nitrogen flow. 2 g of sodium carbonate (Na.sub.2CO.sub.3) were added and, outside the dry-box, ml of MilliQ water were added. Plate-boiling was achieved under magnetic stirring for about 30 minutes. After cooling, 1/5 diluted sulfuric acid (H.sub.2SO.sub.4) was added, up to acid reaction and titration with silver nitrate (AgNO.sub.3) 0.1 N was carried out by a potenziometric titrator.

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

(11) The determination of carbon, hydrogen and nitrogen, in the vanadium bis-imine complexes used for the aim of the present invention, as well as in the ligands used for the aim of the present invention, was carried out by a Carlo Erba Mod. 1106 automated analyzer.

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

(13) .sup.13C-HMR and .sup.1H-HMR spectra were registered by a nuclear magnetic resonance spectrometer mod. Bruker Avance 400, using tetrachloroethane deuterated (C.sub.2D.sub.2Cl.sub.4) at 103 C., and hexamethyldisiloxane (HMDS) as internal standard. For this aim, polymer solution having concentrations equal to 10% by weight with respect to the total weight of the polymer solution were used.

(14) The microstructure of the polymers [i.e. content of cis-1,4(%) units] was determined through the analysis of the above-mentioned spectra according to what reported in literature by Mochel, V. D., in Journal of Polymer Science Part A-1: Polymer Chemistry (1972), Vol. 10, Issue 4, pag. 1009-1018.

(15) Spectra FT-IR (Solid State, UATR)

(16) The FT-IR spectra (solid state, UATR) were registered by Bruker IFS 48 spectrophotometer equipped with an horizontal ATR linkage Thermo Spectra-Tech. 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.

(17) The FT-IR spectra (solid state, UATR) of the used vanadium bis-imine complexes object of the present invention, were obtained by inserting samples of the vanadium bis-imine complex to be analyzed in said section.

(18) IR Spectra

(19) The IR (FT-IR) spectra were registered by Thermo Nicolet Nexus 670 and Bruker IFS 48 spectrophotometers.

(20) The I.R. spectra (FT-IR) of the ligands used in the present invention, were obtained by dispersing the ligand to be analyzed in potassium bromide (KBr) anhydrous (KBr discs), or in nujol suspension.

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

(22) Determination of the Molecular Weight

(23) The determination of the molecular weight (MW) of the polymers obtained was carried out by GPC (Gel Permeation Chromatography) by operating under the following conditions: Agilent 1100 pump; detector I.R. Agilent 1100; PL Mixed-A columns; solvent/eluent: tetrahydrofuran (THF); flow: 1 ml/min; temperature: 25 C.; calculation of the molecular mass: Universal Calibration method.

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

Example 1

(25) Synthesis of the Ligand Having Formula (L1)

(26) ##STR00005##

(27) A solution of aniline (9.3 g-100 mmol) in methanol (80 ml), a solution of 2,3-butandione (4.3 g-50 mmol) in methanol (20 ml) and some drops of formic acid were loaded, consecutively and under stirring, into a reactor of 500 ml equipped with a magnetic stirrer. The obtained yellow solution was left, under stirring, at room temperature, for about 2 hours, up to obtain the precipitation of a yellow solid product. The whole was left at rest for 14 hours and, then, said solid product was recovered by filtration and dried, under vacuum, at room temperature, obtaining 11.6 g of a yellowish solid product (yield=98%) having formula (L1).

(28) FT-IR (nujol): 1633 cm.sup.1 .sub.(CN).

(29) Molecular weight (MW): 236.32.

(30) Elementary analysis [found (calculated for C.sub.16H.sub.16N.sub.2)]: C: 81.42% (81.32%); H: 6.33% (6.82%); N: 11.92% (11.85%).

Example 2

(31) Synthesis of the Ligand Having Formula (L2)

(32) ##STR00006##

(33) A solution of o-toluidina (9.6 g-90 mmol) in methanol (50 ml), a solution of 2.3-butandione (3.875 g-45 mmol) in methanol (30 ml) and some drops of formic acid were loaded, consecutively and under stirring, into a reactor of 500 ml equipped with a magnetic stirrer. The obtained yellow solution was left, under stirring, at room temperature, for about 2 hours, up to obtain the precipitation of a yellow solid product. The whole was left at rest for 14 hours and, then, said solid product was recovered by filtration and dried, under vacuum, at room temperature, obtaining 9.7 g of a yellowish solid product (yield=81%) having formula (L2).

(34) FT-IR (nujol): 1637 cm.sup.1 .sub.(CN).

(35) Molecular weight (MW): 264.37.

(36) Elementary analysis [found (calculated for C.sub.18H.sub.20N.sub.2)]: C: 81.75% (81.78%); H: 7.65% (7.63%); N: 10.58% (10.60%).

Example 3

(37) Synthesis of the Ligand Having Formula (L3)

(38) ##STR00007##

(39) A solution of 2 tert-butylaniline (13.43 g-90 mmol) in methanol (50 ml) and some drops of formic acid, were loaded, consecutively and under stirring, into a reactor of 500 ml equipped with a magnetic stirrer, and then a solution of 2,3-butandione (3.875 g-45 mmol) in 30 ml of methanol was added dropwise under stirring. The obtained yellow solution was left, under stirring, at room temperature, for about 2 hours, up to obtain the precipitation of a yellow solid product. The whole was left at rest for 14 hours and, then, said solid product was recovered by filtration and dried, under vacuum, at room temperature, obtaining 14.1 g of a yellowish solid product (yield=90%) having formula (L3).

(40) FT-IR (nujol): 1638 cm.sup.1 .sub.(CN).

(41) Molecular weight (MW): 348.53.

(42) Elementary analysis [found (calculated for C.sub.24H.sub.32N.sub.2)]: C: 81.95% (82.71%); H: 9.26% (9.25%); N: 8.02% (8.04%).

Example 4

(43) Synthesis of the Ligand Having Formula (L4)

(44) ##STR00008##

(45) A solution of 2,6-di-iso-propylaniline (15.96 g-90 mmol) in methanol (80 ml) and some drops of formic acid, were loaded, consecutively and under stirring, into a reactor of 500 ml equipped with a magnetic stirrer, and then a solution of 2,3-butandione (3.875 g-45 mmol) in methanol (80 ml) was added dropwise under stirring. The obtained yellow solution was left, under stirring, at room temperature, for about 2 hours, up to obtain the precipitation of a yellow solid product. The whole was left at rest for 14 hours and, then, said solid product was recovered by filtration and dried, under vacuum, at room temperature, obtaining 15.4 g of a yellowish solid product (yield=84%) having formula (L4).

(46) FT-IR (nujol): 1640 cm.sup.1 .sub.(CN).

(47) Molecular weight (MW): 404.64.

(48) Elementary analysis [found (calculated for C.sub.28H.sub.40N.sub.2)]: C: 82.86% (83.11%); H: 9.97% (9.96%); N: 6.94% (8.92%).

Example 5

(49) Synthesis of the Ligand Having Formula (L5)

(50) ##STR00009##

(51) A solution of glyoxal (14.51 g-100 mmol) (aqueous solution 40% by weight), further diluted with methanol (80 ml) and distilled water (8 ml), and after cooling at 0 C. by a water/ice bath, a solution of o-toluidine (21.43 g-200 mmol) in methanol (25 ml), were loaded, consecutively and under stirring, into a reactor of 500 ml equipped with a magnetic stirrer. The obtained yellow solution was left, under stirring, at room temperature, for about 30 minutes, up to obtain the precipitation of a yellow solid product. Said solid product was recovered by filtration, washed with methanol, recrystallized from methanol and dried, under vacuum, at room temperature, obtaining 23 g of a microcrystalline yellowish solid product (yield=97%) having formula (L5).

(52) FT-IR (nujol): 1605 cm.sup.1 .sub.(CN).

(53) Molecular weight (MW): 236.26.

(54) Elementary analysis [found (calculated for C.sub.16H.sub.16N.sub.2)]: C: 81.42% (81.32%); H: 6.80% (6.82%); N: 12.00% (11.85%).

Example 6

(55) Synthesis of the Ligand Having Formula (L6)

(56) ##STR00010##

(57) 2 tert-butylaniline (14.924 g-100 mmol) dissolved in a mixture of methanol and distilled water (50 ml+100 ml) and, after cooling at 0 C. by a water/ice bath, a solution of glyoxal (7.26 g-50 mmol) (aqueous solution at 40% by weight), were loaded, consecutively and under stirring, into a reactor of 500 ml equipped with a magnetic stirrer. The obtained yellow solution was left, under stirring, at room temperature, for about 30 minutes, up to obtain the precipitation of a yellow solid product. Said solid product was recovered by filtration, washed with methanol, recrystallized from pentane and dried, under vacuum, at room temperature, obtaining 12 g of a microcrystalline yellowish solid product (yield=75%) having formula (L6).

(58) FT-IR (nujol): 1608 cm.sup.1 .sub.(CN).

(59) Molecular weight (MW): 320.48.

(60) Elementary analysis [found (calculated for C.sub.22H.sub.28N.sub.2)]: C: 82.42% (82.45%); H: 8.80% (8.81%); N: 8.76% (8.74%).

Example 7

(61) Synthesis of the Ligand Having Formula (L7)

(62) ##STR00011##

(63) A solution of 2,6-di-iso-propylaniline (17.73 g-100 mmol) in methanol (25 ml), some drops of acetic acid and, after heating at 50 C., a solution of glyoxal (7.26 g-50 mmol) (aqueous solution at 40% by weight) in methanol (25 ml), were loaded, consecutively and under stirring, into a reactor of 500 ml equipped with a magnetic stirrer. The obtained yellow solution was left, under stirring, at 50 C., for 15 minutes, and then at room temperature for 24 hours, up to obtain the precipitation of a yellow solid product. Said solid product was recovered by filtration, washed with methanol, recrystallized from pentane and dried, under vacuum, at room temperature, obtaining 16.8 g of a microcrystalline yellowish solid product (yield=90%) having formula (L7).

(64) FT-IR (nujol): 1608 cm.sup.1 .sub.(CN).

(65) Molecular weight (MW): 376.59.

(66) Elementary analysis [found (calculated for C.sub.26H.sub.36N.sub.2)]: C: 82.91% (82.93%); H: 9.80% (9.64%); N: 7.70% (7.74%).

Example 8

(67) Synthesis of the Ligand Having Formula (L8)

(68) ##STR00012##

(69) 2,4,6-trimethylaniline (13.52 g-100 mmol) dissolved in a mixture of methanol and distilled water (50 ml+100 ml) and, after cooling at 0 C. with a bath of water/ice, a solution of glyoxal (7.26 g-50 mmol) (40% by weight aqueous solution) were loaded, consecutively and under stirring, into a reactor of 500 ml equipped with a magnetic stirrer. The obtained yellow solution was left, under stirring, at room temperature, for about 2 hours, up to obtain the precipitation of a yellow solid product. Said solid product was recovered by filtration, washed with methanol, recrystallized from pentane and dried, under vacuum, at room temperature, obtaining 12 g of a microcrystalline yellowish solid product (yield=82%) having formula (L8).

(70) FT-IR (nujol): 1616 cm.sup.1 .sub.(CN).

(71) Molecular weight (MW): 292.42.

(72) Elementary analysis [found (calculated for C.sub.20H.sub.24N.sub.2)]: C: 82.00% (82.15%); H: 8.28% (8.27%); N: 9.50% (9.58%).

Example 9

(73) Synthesis of the VCl.sub.3(L1) (THF) Complex [Sample BIB1]

(74) ##STR00013##

(75) A bright yellow toluene solution (20 ml) of the ligand having formula (L1) (0.68 g; 2.88 mmol; molar ratio L1/V=1), obtained as described in Example 1, was added dropwise into a tailed flask of 100 ml, to a suspension of vanadium(III)chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (1.08 g; 2.89 mmol) in toluene (15 ml). The whole was left to react, at room temperature, overnight thus obtaining a first portion of dark red crystals which were separated by filtration and then dried, under vacuum, at room temperature. The solution obtained after filtration, was concentrated under vacuum and, then, pentane was added (40 ml): the whole was left at rest at room temperature, overnight, thus obtaining a second portion of dark red crystals, which were separated by filtration and then dried, under vacuum, at room temperature. On the whole, 0.92 g (yield=68.0%) of a dark red crystalline solid product corresponding to the VCl.sub.3(L1) (THF) complex were obtained.

(76) Elementary analysis [found (calculated for C.sub.20H.sub.24Cl.sub.3N.sub.2OV)]: C: 51.70% (51.58%); H: 5.45% (5.19%); Cl: 23.00% (22.84%); N: 6.10% (6.02%); V: 10.80% (10.94%).

(77) Molecular weight (MW): 465.72.

(78) FT-IR (.sub.(max)cm.sup.1): 3057 m, 3051 m 2982 br, 1592 s, 1486 s, 1451 m, 1419 w, 1380 m, 1237 s, 1140 w, 1072 w, 1015 m.

Example 10

(79) Synthesis of the VCl.sub.3(L2) (THF) Complex [Sample IP56]

(80) ##STR00014##

(81) A yellow toluene solution (20 ml) of the ligand having formula (L2) (0.613 g; 2.32 mmol; molar ratio L2/V=1), obtained as described in Example 2, in toluene (20 ml) was added dropwise into a tailed flask of 100 ml, to a suspension of vanadium(III)chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (0.867 g; 2.32 mmol) in toluene (15 ml): the whole was left to react, at room temperature, overnight. Then, pentane was added (50 ml) thus obtaining a suspension which was filtered: the residue remained on the filter was dried, under vacuum, at room temperature, thus obtaining a brown powder 0.807 g (yield=71.1%) corresponding to the VCl.sub.2(L2) (THF) complex.

(82) Elementary analysis [found (calculated for C.sub.22H.sub.28Cl.sub.3N.sub.2OV)]: C: 53.65% (53.51%); H: 5.85% (5.72%); Cl: 21.45% (21.54%); N: 5.80% (5.67%); V: 10.40% (10.32%).

(83) Molecular weight (MW): 493.77.

(84) In FIG. 1 the FT-IR spectrum of the obtained VCl.sub.3(L2) (THF) complex (Absorbance; Wavenumber) is reported.

Example 11

(85) Synthesis of the VCl.sub.3(L3) Complex [IP61 Sample]

(86) ##STR00015##

(87) A yellow toluene solution (15 ml) of the ligand having formula (L3) (0.523 g; 1.5 mmol; molar ratio L3/V=1), obtained as described in Example 3, was added dropwise into a tailed flask of 100 ml, to a suspension of vanadium(III)chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (0.560 g; 1.5 mmol) in toluene (10 ml): the whole was left to react, at room temperature, overnight. Then, pentane was added (40 ml) thus obtaining a suspension which was filtered: the residue remained on the filter was dried, under vacuum, at room temperature, thus obtaining a light brown powder 0.489 g (yield=64.5%) corresponding to the VCl.sub.3(L3) complex.

(88) Elementary analysis [found (calculated for C.sub.28H.sub.32Cl.sub.3N.sub.2V)]: C: 56.86% (56.99%); H: 6.10% (6.38%); Cl: 21.20% (21.03%); N: 5.35% (5.54%); V: 10.30% (10.07%).

(89) Molecular weight (MW): 505.82.

(90) In FIG. 2 the FT-IR spectrum of the obtained VCl.sub.3(L3) complex (Absorbance; Wavenumber) is reported.

Example 12

(91) Synthesis of the VCl.sub.3(L4) Complex [GL1403 Sample]

(92) ##STR00016##

(93) A yellow/brown toluene solution (30 ml) of the ligand having formula (L4) (1.69 g; 4.18 mmol; molar ratio L4/V=1,1), obtained as described in Example 4, was added dropwise into a tailed flask of 100 ml, to a suspension of vanadium(III)chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (1.42 g; 3.80 mmol) in toluene (60 ml): the whole was left to react, at room temperature, overnight. Then, the obtained solution was concentrated by evaporation, under vacuum, at about 20 ml, then pentane (70 ml) was added and the whole was left at 20 C., overnight. The obtained suspension was filtered: the residue remained on the filter was dried, under vacuum, at room temperature, thus obtaining a brown microcrystalline powder 1,66 g (yield=78%) corresponding to the VCl.sub.3(L4)complex.

(94) Elementary analysis [found (calculated for C.sub.28H.sub.40Cl.sub.3N.sub.2V)]: C: 59.70% (59.85%); H: 7.10% (7.17%); Cl: 19.20% (18.93%); N: 5.15% (4.99%); V: 9.20% (9.07%).

(95) Molecular weight (MW): 561.93.

Example 13

(96) Synthesis of the VCl.sub.3(L5) (THF) Complex [IP55 Sample]

(97) ##STR00017##

(98) A yellow toluene solution (15 ml) of the ligand having formula (L5) (0.583 g; 2.47 mmol; molar ratio L5/V=1), obtained as described in Example 5, was added dropwise into a tailed flask of 100 ml, to a suspension of vanadium(III)chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (0.906 g; 2.42 mmol) in toluene (15 ml): the whole was left to react, at room temperature, overnight. Then, pentane was added (30 ml) thus obtaining a suspension which was filter: the residue remained on the filter was dried, under vacuum, at room temperature, thus obtaining a dark brown powder 0.604 g (yield=53.6%) corresponding to the VCl.sub.3(L5) (THF) complex.

(99) Elementary analysis [found (calculated for C.sub.20H.sub.24Cl.sub.3N.sub.2V)]: C: 51.54% (51.58%); H: 5.40% (5.19%); Cl: 23.05% (22.84%); N: 6.18% (6.02%); V: 10.80% (10.94%).

(100) Molecular weight (MW): 465.72.

(101) In FIG. 3 the FT-IR spectrum of the obtained VCl.sub.3(L5) (THF) complex (Absorbance; Wavenumber) is reported.

Example 14

(102) Synthesis of the VCl.sub.3(L6) Complex [IP62 Sample]

(103) ##STR00018##

(104) A yellow toluene solution (20 ml) of the ligand having formula (L6) (0.839 g; 2.6 mmol; molar ratio L6/V=1), obtained as described in Example 6, was added dropwise into a tailed flask of 100 ml, to a suspension of vanadium(III)chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (0.964 g; 2.6 mmol) in toluene (15 ml): the whole was left to react, at room temperature, overnight. Then, pentane was added (50 ml) thus obtaining a suspension which was filtered: the residue remained on the filter was dried, under vacuum, thus obtaining a dark violet powder 0.864 g (yield=70.4%) corresponding to the VCl.sub.3(L6) complex.

(105) Elementary analysis [found (calculated for C.sub.22H.sub.28Cl.sub.3N.sub.2OV)]: C: 54.95% (55.31%); H: 6.08% (5.91%); Cl: 22.70% (22.26%); N: 5.76% (5.86%); V: 10.60% (10.66%).

(106) Molecular weight (MW): 477.77.

(107) In FIG. 4 the FT-IR spectrum of the obtained VCl.sub.3(L6) complex (Absorbance; Wavenumber) is reported.

Example 15

(108) Synthesis of the VCl.sub.3(L7) Complex [BIB2 Sample]

(109) ##STR00019##

(110) A yellow toluene solution (15 ml) of the ligand having formula (L7) (0.79 g; 2.09 mmol; molar ratio L7/V=1), obtained as described in Example 7, was added dropwise into a tailed flask of 100 ml, to a suspension of vanadium(III)chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (0.78 g; 2.09 mmol) in toluene (10 ml): the whole was left to react, at room temperature, overnight. Then, the obtained solution was concentrated, by evaporation, under vacuum, to about 10 ml, then pentane (50 ml) was added and the whole was left at 20 C., overnight. The obtained suspension was filtered: the residue remained on the filter was dried, under vacuum, at room temperature, thus obtaining 0.66 g (yield=59%) of a brown powder corresponding to the VCl.sub.3(L7) complex.

(111) Elementary analysis [found (measured for C.sub.26H.sub.36Cl.sub.3N.sub.2V)]: C: 59.00% (58.49%); H: 6.90% (6.80%); Cl: 20.10% (19.92%); N: 5.10% (5.25%); V: 9.40% (9.54%).

(112) Molecular weight (MW): 533.88.

(113) FT-IR (.sub.(max)cm.sup.1): 2972 s, 2926 m, 2875 m, 1580 v, 1490 m, 1461 m, 1384 w, 1364 w, 1333 w, 1174 w, 1097 m, 1056 m, 1041 m, 1010 m.

Example 16

(114) Synthesis of the VCl.sub.3(L8) Complex [Sample IP68]

(115) ##STR00020##

(116) A yellow toluene solution (20 ml) of the ligand having formula (L8) (0.680 g; 2.33 mmol; molar ratio L8/V=1,1), obtained as described in Example 8, was added dropwise into a tailed flask of 100 ml, to a suspension of vanadium(III)chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (0.779 g; 2.09 mmol) in toluene (15 ml): the whole was left to react, at room temperature, overnight. Then, pentane (50 ml) was added thus obtaining a suspension which was filtered: the residue remained on the filter was dried, under vacuum, at room temperature, thus obtaining 0.890 g (yield=95%) of a dark brown/violet powder corresponding to the VCl.sub.3(L8) complex.

(117) Elementary analysis [found (calculated for C.sub.20H.sub.24Cl.sub.3N.sub.2V)]: C: 53.20% (53.41%); H: 5.25% (5.38%); Cl: 23.55% (23.65%); N: 6.25% (6.23%); V: 11.40% (11.33%).

(118) Molecular weight (MW): 449.72.

(119) In FIG. 5 the FT-IR spectrum of the obtained VCl.sub.3(L8) complex (Absorbance; Wavenumber) is reported.

Example 17 (GR1)

(120) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.37 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; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L1) (THF) complex (sample BIB1) (2.33 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.66 mg) obtained as described in Example 9. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.215 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 85.5%): further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(121) In FIG. 6 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

Example 18 (GR2)

(122) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.37 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L1) (THF) complex (sample BIB1) (2.33 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.66 mg) obtained as described in Example 9. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.328 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 85.7%): further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(123) In FIG. 7 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

Example 19 (IP58)

(124) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.23 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; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L2) (THF) complex (sample IP56) (2.47 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.94 mg) obtained as described in Example 10. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.171 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 85.9%): further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(125) In FIG. 8 the GPC curve (Gel Permeation Chromatography) of the obtained polybutadiene is reported.

Example 20 (Gr3)

(126) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.23 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; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L2) (THF) complex (sample IP56) (2.47 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.94 mg) obtained as described in Example 10. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.256 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 86.5%): further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(127) In FIG. 9 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

Example 21 (IP63)

(128) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 6.81 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; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L3) complex (sample IP61) (2.89 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.78 mg) obtained as described in Example 11. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.299 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 85.7%): further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(129) In FIG. 10 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

(130) In FIG. 11 the GPC curve (Gel Permeation Chromatography) of the obtained polybutadiene is reported.

Example 22 (GR4)

(131) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.23 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L3) complex (sample IP61) (2.89 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.78 mg) obtained as described in Example 11. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.385 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 84.2%): further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

Example 23 (GR5)

(132) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 6.90 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; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L4) complex (sample GL1403) (2.8 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.6 mg) obtained as described in Example 12. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.442 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 82%): further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

Example 24 (MP450)

(133) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 6.9 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L4) complex (sample GL1403) (2.8 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.6 mg) obtained as described in Example 12. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.515 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 81.7%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(134) In FIG. 12 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

Example 25 (IP57)

(135) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.37 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; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L5) (THF) complex (sample IP55) (2.33 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.66 mg) obtained as described in Example 13. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.709 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 80.4%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(136) In FIG. 13 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

(137) In FIG. 14 the .sup.1H-NMR (below) and .sup.13C-NMR (above) spectra of the obtained polybutadiene are reported.

Example 26 (IP78)

(138) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.4 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L5) (THF) complex (sample IP55) (2.3 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.66 mg) obtained as described in Example 13. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 1.020 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 77.2%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(139) In FIG. 15 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

(140) In FIG. 16 the .sup.1H-NMR (below) and .sup.13C-NMR (above) spectra of the obtained polybutadiene are reported.

Example 27 (IP59)

(141) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 8.37 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane modified (MAO-modified) in toluene solution (5.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L5) (THF) complex (sample IP55) (2.33 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.66 mg) obtained as described in Example 13. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.951 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 72.1%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(142) In FIG. 17 the .sup.1H-NMR (below) and .sup.13C-NMR (above) spectra of the obtained polybutadiene are reported.

Example 28 (IP64)

(143) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 6.95 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; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L6) complex (sample IP62) (2.75 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.5 mg) obtained as described in Example 14. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.157 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 82.2%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(144) In FIG. 18 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

(145) In FIG. 19 the .sup.1H-NMR (below) and .sup.13C-NMR (above) spectra of the obtained polybutadiene are reported.

Example 29 (GR6)

(146) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 6.95 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L6) complex (sample IP62) (2.75 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.5 mg) obtained as described in Example 14. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.378 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 76.6%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(147) In FIG. 20 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

Example 30 (IP30)

(148) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.37 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane modified (MAO-modified) in toluene solution (5.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L6) complex (sample IP62) (2.4 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.8 mg) obtained as described in Example 14. The whole was maintained, under magnetic stirring, at 20 C., for 70 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.836 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 76%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

Example 31 (GR7)

(149) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.03 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; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L7) complex (sample BIB2) (2.67 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.34 mg) obtained as described in Example 15. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.669 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 77.9%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1. In FIG. 21 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

Example 32 (GR8)

(150) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.03 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L7) complex (sample BIB2) (2.67 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.34 mg) obtained as described in Example 15. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.669 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 87.2%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(151) In FIG. 22 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

Example 33 (IP71)

(152) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.09 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; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L8) complex (sample IP68) (2.61 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.22 mg) obtained as described in Example 16. The whole was maintained, under magnetic stirring, at 20 C., for 5 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.321 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 70%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1. In FIG. 23 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported.

Example 34 (IP69)

(153) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 7.09 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L8) complex (sample IP68) (2.61 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.22 mg) obtained as described in Example 16. The whole was maintained, under magnetic stirring, at 20 C., for 3 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 1.2 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 71.6%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

(154) In FIG. 24 the FT-IR spectrum of the polybutadiene obtained (Absorbance; Wavenumber) is reported. In FIG. 25 the GPC curve (Gel Permeation Chromatography) of the obtained polybutadiene is reported.

Example 35 (IP70)

(155) 2 ml of 1,3-butadiene equal to about 1.4 g were cold condensed (20 C.) in a test tube of 25 ml. Then, 8.09 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-modified (MAO-modified) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L8) complex (sample IP68) (2.61 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.22 mg) obtained as described in Example 16. The whole was maintained, under magnetic stirring, at 20 C., for 24 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.132 g of polybutadiene having a cis-1,4/trans-1,4/1,2 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 72.4%: further characteristics of the process and of the polybutadiene obtained are reported in Table 1.

Example 36 (MP451)

(156) 2 ml of isoprene equal to about 1.34 g were introduced in a test tube of 25 ml. Then, 6.9 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L4) complex (sample GL1403) (2.8 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.6 mg) obtained as described in Example 12. The whole was maintained, under magnetic stirring, at 20 C., for 21 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.257 g of polyisoprene having a cis-1,4/trans-1,4/3,4 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 84.6%: further characteristics of the process and of the polyisoprene obtained are reported in Table 2.

(157) In FIG. 26 the FT-IR spectrum of the polyisoprene obtained (Absorbance; Wavenumber) is reported.

(158) In FIG. 27 the .sup.1H-NMR (below) and .sup.13C-NMR (above) spectra of the obtained polyisoprene are reported.

Example 37 (IP79)

(159) 2 ml of isoprene equal to about 1.34 g were introduced in a test tube of 25 ml. Then, 7.4 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 1.010.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L5) (THF) complex (sample IP55) (2.33 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.66 mg) obtained as described in Example 13. The whole was maintained, under magnetic stirring, at 20 C., for 21 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.647 g of polyisoprene having a cis-1,4/trans-1,4/3,4 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 77.2%: further characteristics of the process and of the polyisoprene obtained are reported in Table 2.

(160) In FIG. 28 the FT-IR spectrum of the polyisoprene obtained (Absorbance; Wavenumber) is reported.

(161) In FIG. 29 the .sup.1H-NMR (below) and .sup.13C-NMR (above) spectra of the obtained polyisoprene are reported.

Example 38 (IP80)

(162) 2 ml of isoprene equal to about 1.34 g were introduced in a test tube of 25 ml. Then, 7.4 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, then, the VCl.sub.3(L5) (THF) complex (sample IP55) (2.33 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 4.66 mg) obtained as described in Example 13. The whole was maintained, under magnetic stirring, at 20 C., for 21 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.235 g of polyisoprene having a cis-1,4/trans-1,4/3,4 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 80.9%: further characteristics of the process and of the polyisoprene obtained are reported in Table 2.

(163) In FIG. 30 the FT-IR spectrum of the polyisoprene obtained (Absorbance; Wavenumber) is reported.

(164) In FIG. 31 the .sup.1H-NMR (below) and .sup.13C-NMR (above) spectra of the obtained polyisoprene are reported.

(165) In FIG. 32 the GPC curve (Gel Permeation Chromatography) of the obtained polyisoprene is reported.

Example 39 (IP81)

(166) 2 ml of isoprene equal to about 1.34 g were introduced in a test tube of 25 ml. Then, 7.1 ml of toluene were added and the temperature of the solution thus obtained was brought to 20 C. Then, methylaluminoxane-dry (MAO-dry) in toluene solution (6.3 ml; 110.sup.2 moles, equal to about 0.58 g) was added and, then, the VCl.sub.3(L8) complex (sample IP68) (2.61 ml of toluene suspension at a concentration equal to 2 mg/ml; 110.sup.5 moles, equal to about 5.22 mg) obtained as described in Example 16. The whole was maintained, under magnetic stirring, at 20 C., for 21 hours. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The obtained polymer was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox 1076 (Ciba) antioxidant obtaining 0.14 g of polyisoprene having a cis-1,4/trans-1,4/3,4 mixed structure having a content of trans-1,4 and cis-1,4 units equal to 80.6%: further characteristics of the process and of the polyisoprene obtained are reported in Table 2.

(167) In FIG. 33 the FT-IR spectrum of the polyisoprene obtained (Absorbance; Wavenumber) is reported.

(168) In FIG. 34 the GPC curve (Gel Permeation Chromatography) of the obtained polyisoprene is reported.

(169) TABLE-US-00001 TABLE 1 Polymerization of 1,3-butadiene with catalytic systems comprising vanadium bis-imine complexes Temperature Time Conversion cis-1,4 trans-1,4 1,2 M.sub.w Example ( C.) (h) (%) (%) (%) (%) (g mol.sup.1) M.sub.w/M.sub.n 17 20 5 15.4 80.5 5.0 14.5 65000 2.0 18 20 5 23.4 82.9 2.8 14.3 125000 2.5 19 20 5 12.2 66.8 19.1 14.1 39000 1.8 20 20 5 18.3 64.7 21.8 13.5 95000 2.0 21 20 5 21.4 78.1 7.6 14.2 52300 1.9 22 20 5 27.5 75.9 8.3 15.8 135000 2.2 23 20 5 31.6 65.9 16.1 18.0 48700 2.3 24 20 5 36.8 61.3 20.4 18.3 87800 2.4 25 20 5 50.6 77.0 3.4 19.6 63000 2.5 26 20 5 72.9 61.8 15.4 22.8 115800 2.4 27 20 22 67.9 68.7 3.4 27.9 89800 2.6 28 20 5 11.2 63.3 18.9 17.8 42300 2.5 29 20 5 27 59.9 16.7 23.4 105000 2.4 30 20 70 59.7 61.5 14.5 24.0 59200 3.2 31 20 5 47.8 72.7 5.2 22.1 74500 2.7 32 20 5 66.3 68.7 18.5 12.8 148000 2.5 33 20 5 2.9 66.0 4.0 30.0 67600 2.8 34 20 3 85 61.4 10.2 28.4 111000 3.3 35 20 24 9.4 62.6 9.8 27.6 77900 3.0

(170) TABLE-US-00002 TABLE 2 Polymerization of isoprene with catalytic systems compriding vanadium bis-imine complexes Temperature Time Conversion cis-1,4 trans-1,4 3,4 M.sub.w Example ( C.) (h) (%) (%) (%) (%) (g mol.sup.1) M.sub.w/M.sub.n 36 20 21 19.1 36.7 47.9 15.4 43700 2.6 37 20 21 47.6 70.6 6.6 22.8 105000 3.1 38 20 21 17.3 80.9 0 19.1 18900 2.3 39 20 21 10.3 73.8 6.8 19.4 24900 2.6