OXO-NITROGENATED VANADIUM COMPLEX, CATALYTIC SYSTEM COMPRISING SAID OXO-NITROGENATED VANADIUM COMPLEX AND PROCESS FOR (CO)POLYMERISING CONJUGATED DIENES

Abstract

An oxo-nitrogenated vanadium complex having the general formula (I): in which: R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7, mutually identical or different, represent a hydrogen atom; or are selected from optionally halogenated, linear or branched 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, mutually identical or different, represent a halogen atom such as, for example, chlorine, bromine, iodine, preferably chlorine; or are selected from linear or branched C.sub.1-C.sub.20, preferably C.sub.1-C.sub.15, alkyl groups, —OCOR.sub.8 groups or —OR.sub.8 groups in which R.sub.8 is selected from linear or branched C.sub.1-C.sub.20, preferably C.sub.1-C.sub.15, alkyl groups; Y is selected from ethers such as, for example, diethyl ether, tetrahydrofuran (THF), dimethoxyethane, preferably is tetrahydrofuran (THF); n is 0 or 1. Said oxo-nitrogenated vanadium complex having the general formula (I) may advantageously be used in a catalytic system for (co)polymerising conjugated dienes.

Claims

1. An oxo-nitrogenated vanadium complex having the general formula (I): ##STR00009## in which: R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7, mutually identical or different, represent a hydrogen atom; or are selected from optionally halogenated, linear or branched C.sub.1-C.sub.20, optionally substituted cycloalkyl groups, optionally substituted aryl groups; X.sub.1 and X.sub.2, mutually identical or different, represent a halogen atom; or are selected from linear or branched C.sub.1-C.sub.20alkyl groups, —OCOR.sub.8 groups or —OR.sub.8 groups in which R.sub.8 is selected from linear or branched C.sub.1-C.sub.20alkyl groups; Y is selected from ethers; n is 0 or 1.

2. An oxo-nitrogenated vanadium complex having the general formula (I) according to claim 1, in which: R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7, mutually identical or different, represent a hydrogen atom; or are selected from linear or branched C.sub.1-C.sub.20alkyl groups; X.sub.1 and X.sub.2, mutually identical, represent a halogen atom; Y is tetrahydrofuran (THF); n is 0 or 1.

3. A catalytic system for (co)polymerising conjugated dienes comprising: (a) at least one oxo-nitrogenated vanadium complex having the general formula (I) of claim 1; and (b) at least one co-catalyst selected from the group of organo-derivatives of aluminium consisting of: (b.sub.1) aluminium compounds having the general formula (II):
Al(R.sub.9)(R.sub.10)(R.sub.11)   (II) in which R.sub.9 represents a hydrogen atom, or a fluorine atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, aryl groups, alkylaryl groups, arylalkyl groups, alkoxy groups; R.sub.10 and R.sub.11, mutually identical or different, are selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, aryl groups, alkylaryl groups, arylalkyl groups; (b.sub.2) aluminoxanes having the general formula (III):
(R.sub.12).sub.2—Al—O—[—Al(R.sub.13)—O—].sub.m—Al—(R.sub.14).sub.2   (III) in which R.sub.12, R.sub.13 and R.sub.14, mutually identical or different, represent a hydrogen atom, or a halogen atom; or are selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, aryl groups, said groups being optionally substituted with one or more atoms of silicon or germanium; and m is an integer ranging from 0 to 1000; (b.sub.3) partially hydrolysed organo-aluminium derivatives; (b.sub.4) halogen alkylaluminiums having the general formula (IV) or (V):
Al(R.sub.15).sub.p(X.sub.3).sub.3-p   (IV)
Al.sub.2(R.sub.15).sub.q(X.sub.3).sub.3-q   (V) in which p is 1 or 2; q is an integer ranging from 1 to 5; R.sub.15, mutually identical or different, are selected from linear or branched C.sub.1-C.sub.20 alkyl groups; X.sub.3 represents an atom of chlorine or bromine; or mixtures thereof.

4. A catalytic system for (co)polymerising conjugated dienes according to claim 3, in which said co-catalyst is selected from aluminoxanes (b.sub.2) having the general formula (III).

5. A process for (co)polymerising conjugated dienes, characterised in that it uses the catalytic system according to claim 3.

6. A process for polymerising 1,3-butadiene or isoprene, characterised in that it uses the catalytic system according to claim 3.

Description

EXAMPLES

Reagents and Materials

[0092] The following list shows the reagents and materials used in the subsequent examples of the invention, any optional pretreatments and the manufacturers thereof: [0093] anhydrous vanadium trichloride (Aldrich): degree of purity 99.9%, used as such; [0094] vanadium(III) chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3]: prepared as described by Manzer L. E. et al., “Inorganic Syntheses” (1982), vol. 21, pp. 135-140; [0095] 2,4-pentanedione (Aldrich): used as such; [0096] aniline (Aldrich): distilled under reduced pressure and stored under an inert atmosphere; [0097] 2,4,6-trimethylaniline (Aldrich): used as such; [0098] o-toluidine (Aldrich): used as such; [0099] formic acid (Aldrich): used as such; [0100] ethyl ether (Aldrich): used as such; [0101] toluene (Fluka): degree of purity >99.5%, refluxed over sodium (Na) for about 8 hours, then distilled and stored over molecular sieves under nitrogen; [0102] pentane (Fluka): degree of purity >99%, refluxed over sodium/potassium (Na/K) for about 8 hours, then distilled and stored over molecular sieves under nitrogen; [0103] hexane (Aldrich): used as such; [0104] 1,3-butadiene (Air Liquide): pure, ≧99.5%, evaporated from the container before each production, dried by being passed through a column packed with molecular sieves and condensed inside the reactor which has been pre-cooled to −20° C.; [0105] isoprene (Aldrich): pure, ≧99%, refluxed over calcium hydride for 2 hours, then distilled “trap-to-trap” and stored under a nitrogen atmosphere at 4° C.; [0106] methylaluminoxane (MAO) (10% by weight solution in toluene) (Aldrich): used as such, or in “dry” form (dry MAO) obtained by removing the free trimethylaluminium together with the solvent from the solution in toluene under a vacuum and drying the resultant residue still under a vacuum; [0107] methanol (Carlo Erba, RPE): used as such, or optionally dried by distillation over magnesium (Mg); [0108] hydrochloric acid, 37% aqueous solution (Aldrich): used as such; [0109] 1,2-dichlorobenzene (Aldrich): degree of purity 99%, refluxed over calcium hydride (CaH.sub.2) for about 8 hours, then distilled and stored over molecular sieves under nitrogen; [0110] deuterated tetrachloroethylene (C.sub.2D.sub.2Cl.sub.4) (Acros): used as such; [0111] deuterated chloroform (CDCl.sub.3) (Acros): used as such.

[0112] The analysis and characterisation methods stated below were used.

Elemental Analysis

[0113] a) Determination of Vanadium (V)

[0114] The quantity by weight of vanadium (V) in the oxo-nitrogenated vanadium complexes object of the present invention was determined by placing an accurately weighed aliquot, working in a dry box under a stream of nitrogen, of about 30 mg-50 mg of sample in a platinum crucible of about 30 ml, together with a mixture of 1 ml of 40% hydrofluoric acid (HF) (Aldrich), 0.25 ml of 96% sulfuric acid (H.sub.2SO.sub.4) (Aldrich) and 1 ml of 70% nitric acid (HNO.sub.3) (Aldrich). The crucible was then heated on a plate, increasing the temperature until white sulfuric fumes appeared (about 200° C.). The resultant mixture was cooled to room temperature (20° C.-25° C.), 1 ml of 70% nitric acid (HNO.sub.3) (Aldrich) was added and then heated again until fumes appeared. Once the sequence had been repeated twice, a clear, almost colourless solution was obtained. 1 ml of 70% nitric acid (HNO.sub.3) (Aldrich) and about 15 ml of water were then added cold and the temperature was raised to 80° C. for about 30 minutes. The sample thus prepared was diluted with MilliQ purity water to an accurately weighed weight of about 50 g, in order to obtain a solution on which an instrumental analytical determination was performed by means of a Thermo Optek IRIS Advantage Duo ICP-OES spectrometer (plasma with optical detection) by comparison with solutions of known concentration. For this aim, a calibration curve in the range from 0 ppm-10 ppm was prepared for each analyte by measuring solutions of known content obtained by weight dilution of certified solutions.

[0115] The solution of the sample prepared as above was again weight-diluted in such a manner as to obtain concentrations close to the reference concentrations prior to carrying out spectrophotometric detection. All samples were prepared in duplicate. The results were considered acceptable if the individual results of the duplicate tests differed by no more than 2% relative with respect to the mean value thereof.

[0116] b) Determination of Chlorine

[0117] To this aim, about 30 mg-50 mg samples of the oxo-nitrogenated vanadium complexes object of the present invention were accurately weighed into 100 ml glass beakers in a dry box under a stream of nitrogen. 2 g of sodium carbonate (Na.sub.2CO.sub.3) (Aldrich) were added and, outside the dry box, 50 ml of MilliQ water. The mixture was brought to the boil on a plate and stirred with a magnetic stirrer for about 30 minutes. The mixture was left to cool, sulfuric acid (H.sub.2SO.sub.4) (Aldrich) diluted to ⅕was added until an acidic reaction was obtained and titration was performed with 0.1 N silver nitrate (AgNO.sub.3) (Aldrich) with a potentiometric titrator.

[0118] c) Determination of Carbon, Hydrogen and Nitrogen

[0119] Carbon, hydrogen and nitrogen were determined in the oxo-nitrogenated vanadium complexes provided by the present invention using a Carlo Erba model 1106 automatic analyser.

.sup.13C-NMR and .sup.1H-NMR

[0120] The .sup.13C-NMR and .sup.1H-NMR spectra were recorded with a Bruker Avance 400 nuclear magnetic resonance spectrometer using deuterated tetrachloroethylene (C.sub.2D.sub.2Cl.sub.4) at 103° C. and hexamethyldisiloxane (HDMS) (Aldrich) as internal standard, or using deuterated chloroform (CDCl.sub.3) at 25° C. and tetramethylsilane (TMS) (Aldrich) as internal standard. Polymer solutions having concentrations of 10% by weight relative to the total weight of the polymer solution were used for this aim.

[0121] The microstructure of the polymers was determined by analysing the above-stated spectra on the basis of the details reported in the literature by Mochel, V. D., in “Journal of Polymer Science Part A-1: Polymer Chemistry” (1972), vol. 10, issue 4, pp. 1009-1018, for polybutadiene, and by Sato H. et al., in “Journal of Polymer Science: Polymer Chemistry Edition” (1979), vol. 17, issue 11, pp. 3551-3558, for polyisoprene.

FT-IR Spectra (Solid State, UATR)

[0122] The FT-IR spectra (solid state, UATR) were recorded by means of a Bruker IFS 48 spectrophotometer equipped with a Thermo Spectra-Tech horizontal ATR attachment. The section in which the samples are placed for analysis is a Fresnel ATR accessory (Shelton, Conn, USA) which uses zirconium selenide crystals (ZnSe) with an angle of incidence of 45° in the horizontal direction.

[0123] The FT-IR spectra (solid state, UATR) of the oxo-nitrogenated vanadium complexes object of the present invention were obtained by inserting samples of the oxo-nitrogenated vanadium complex for analysis into said section.

FT-IR Spectra

[0124] The FT-IR spectra were recorded by means of Thermo Nicolet Nexus 670 and Bruker IFS 48 spectrophotometers.

[0125] The FT-IR spectra of the polymers were obtained from polymer films on potassium bromide (KBr) pellets, said films being obtained by deposition of a solution of the polymer for analysis in hot 1,2-dichlorobenzene. The concentration of the analysed polymer solutions was 10% by weight relative to the total weight of the polymer solution.

Thermal Analysis (DSC)

[0126] DSC (“Differential Scanning Calorimetry”) thermal analysis for the aim of determining the melting point (T.sub.m) and the crystallisation temperature (T.sub.c) of the polymers obtained was carried out using a Perkin Elmer Pyris differential scanning calorimeter. To this aim, 5 mg of polymer were analysed at a scanning speed ranging from 1° C./min to 20° C./min, under an inert nitrogen atmosphere.

[0127] DSC (“Differential Scanning Calorimetry”) thermal analysis for the aim of determining the glass transition temperature (T.sub.g) of the polymers obtained was carried out by means of the above-stated calorimeter using the following temperature programme: isotherm for 3 min at +70° C.; cooling from +70° C. to −90° C. at a rate of 10° C./min; isotherm for 3 min at −90° C.; heating from −90° C. to +70° C. at a rate of 10° C./min.

Determination of Molecular Weight

[0128] The molecular weight (MW) of the polymers obtained was determined by GPC (“Gel Permeation Chromatography”) working under the following conditions: [0129] Agilent 1100 pump; [0130] Agilent 1100 IR detector; [0131] Mixed-A PL columns; [0132] solvent/eluent: tetrahydrofuran (THF) (Aldrich); [0133] flow rate: 1 ml/min; [0134] temperature: 25° C.; [0135] calculation of molecular mass: Universal Calibration method.

[0136] The weight-average molecular weight (M.sub.w) and the polydispersion index (PDI) corresponding to the ratio M.sub.w/M.sub.n (M.sub.n=number-average molecular weight) are reported.

Mass Spectra

[0137] The mass spectra of the ligands obtained were recorded with an AT 95S reverse-geometry, double-focusing spectrometer operated by desorption chemical ionisation (DCI) with iso-butane as reactant gas in positive ion mode. The emission current of the filament was calibrated to 0.1 mA with an electron beam energy of 100 eV and with the temperature of the ion source kept at 90° C.

Example 1

Synthesis of the Ligand Having the Formula (L1)

[0138] ##STR00003##

[0139] 5 g (50 mmol) of 2,4-pentanedione together with 100 ml of methanol, a few drops of formic acid and 4.7 g (50 mmol) of aniline were placed in a 500 ml reaction flask equipped with a Dean-Stark trap for azeotropic water removal: the resultant mixture was heated to 85° C. for 4 hours. The mixture was then cooled to room temperature, filtered through a porous membrane and the resultant filtrate was vacuum evaporated, a solid product being obtained. Said solid product was dissolved in ethyl ether (40 ml) and placed in a freezer for 24 hours, a precipitate being obtained. The resultant precipitate was recovered by way of filtration and dried under a vacuum at room temperature, 7 g of a yellowish solid product (yield=80%) having the formula (L1) being obtained.

[0140] Elemental analysis [found (calculated for C.sub.11H.sub.13NO)]: C: 75.20% (75.40%); H: 7.50% (7.48%); N: 8.00% (7.99%).

[0141] Molecular weight (MW): 175.23.

[0142] FT-IR (solid state, UATR, cm.sup.−1): 1590; 1571.

[0143] .sup.1H-NMR (CD.sub.2Cl.sub.2, δ 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).

[0144] GC-MS: M.sup.+=m/z 175.

[0145] FIG. 1 shows the FT-IR spectrum (solid state, UATR) of the resultant ligand (L1).

[0146] FIG. 2 shows the .sup.1H-NMR spectrum of the resultant ligand (L1).

[0147] FIG. 3 shows the GC-MS chromatogram of the resultant ligand (L1).

Example 2

Synthesis of the Ligand Having the Formula (L2)

[0148] ##STR00004##

[0149] 5 g (50 mmol) of 2,4-pentanedione together with 75 ml of benzene, a few drops of formic acid and 6.76 g (50 mmol) of 2,4,6-trimethylaniline were placed in a 500 ml reaction flask equipped with a Dean-Stark trap for azeotropic water removal: the resultant mixture was refluxed for 24 hours. The mixture was then cooled to room temperature, filtered through a porous membrane and the resultant filtrate was vacuum evaporated, a solid product being obtained. Said solid product was dissolved in ethyl ether (10 ml) and placed in a freezer for 24 hours, a precipitate being obtained. The resultant precipitate was recovered by way of filtration and dried under a vacuum at room temperature, 4.8 g of a yellowish solid product (yield=44%) having the formula (L2) being obtained.

[0150] Elemental analysis [found (calculated for C.sub.14H.sub.19NO )]: C: 77.40% (77.38%); H: 9.00% (8.81%); N: 6.32% (6.45%).

[0151] Molecular weight (MW): 217.31.

[0152] FT-IR (solid state, UATR, cm.sup.−1): 1606; 1567.

[0153] .sup.1H-NMR (CD.sub.2Cl.sub.2, δ ppm): 1.61 (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 C.sub.6H.sub.2), 11.82 (s, 1H NH).

[0154] GC-MS: M.sup.+=m/z 217.

[0155] FIG. 4 shows the FT-IR spectrum (solid state, UATR) of the resultant ligand (L2).

[0156] FIG. 5 shows the .sup.1H-NMR spectrum of the resultant ligand (L2).

[0157] FIG. 6 shows the GC-MS chromatogram of the resultant ligand (L2).

Example 3

Synthesis of the Ligand Having the Formula (L3)

[0158] ##STR00005##

[0159] 5 g (50 mmol) of 2,4-pentanedione together with 75 ml of benzene, a few drops of formic acid and 5.36 g (50 mmol) of o-toluidine were placed in a 500 ml reaction flask equipped with a Dean-Stark trap for azeotropic water removal: the resultant mixture was refluxed for 24 hours. The mixture was then cooled to room temperature, filtered through a porous membrane and the resultant filtrate was vacuum evaporated, a solid product being obtained. Said solid product was dissolved in ethyl ether (10 ml) and placed in a freezer for 24 hours, a precipitate being obtained. The resultant precipitate was recovered by way of filtration and dried under a vacuum at room temperature, 5.7 g of a white solid product (yield=60%) having the formula (L3) being obtained.

[0160] Elemental analysis [found (calculated for C.sub.12H.sub.15NO)]: C: 76.31% (76.16%); H: 7.92% (7.99%); N: 7.56% (7.40%).

[0161] Molecular weight (MW): 189.0.

[0162] FT-IR (solid state, UATR, cm.sup.−1): 1595; 1560.

[0163] .sup.1H-NMR (CD.sub.2Cl.sub.2, δ 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).

[0164] GC-MS: M.sup.+=m/z 189.

[0165] FIG. 7 shows the FT-IR spectrum (solid state, UATR) of the resultant ligand (L3).

[0166] FIG. 8 shows the .sup.1H-NMR spectrum of the resultant ligand (L3).

[0167] FIG. 9 shows the GC-MS chromatogram of the resultant ligand (L3).

Example 4

Synthesis of VCl.SUB.2.(L1)(thf) [Sample GT-298]

[0168] ##STR00006##

[0169] The vanadium(III) chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (348 mg; 0.93 mmol) was introduced into a 50 ml side-arm flask together with a yellow-coloured solution of the ligand having the formula (L1) (164 mg; 0.93 mmol; molar ratio L1/V=1), obtained as described in Example 1, in toluene (20 ml). The resultant mixture, which immediately turned reddish on addition of the vanadium(III) chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3], was refluxed for 2 hours, during which time evolution of acidic gases (HCl) was observed. The resultant suspension was allowed to cool to room temperature, the volume was reduced to about 5 ml by evaporation under a vacuum at room temperature, after which hexane (20 ml) was added. The dark red-coloured solid formed was recovered by way of filtration, washed with hexane (2×5 ml) and dried under a vacuum at room temperature, 325 mg (yield=96%) of a dark red-coloured solid product corresponding to the complex VCl.sub.2(L1)(thf) being obtained.

[0170] Elemental analysis [found (calculated for C.sub.15H.sub.20Cl.sub.2NO.sub.2V)]: C: 48.20% (48.93%); H: 5.00% (5.48%); N: 3.42% (3.80%); V: 13.10% (13.84%); Cl: 19.80% (19.26%).

[0171] FT-IR (solid state, UATR, cm.sup.−1): 1592; 1494; 1485.

[0172] FIG. 10 shows the FT-IR spectrum (solid state, UATR) of the resultant complex VCl.sub.2(L1)(thf).

Example 5

Synthesis of VCl.SUB.2.(L2) [Sample GT-301]

[0173] ##STR00007##

[0174] The vanadium(III) chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (374 mg; 1.0 mmol) was introduced into a 50 ml side-arm flask together with a yellow-coloured solution of the ligand having the formula (L2) (218 mg; 1.0 mmol; molar ratio L2/V=1), obtained as described in Example 2, in toluene (20 ml). The resultant mixture, which immediately turned reddish on addition of the vanadium(III) chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3], was refluxed for 3 hours, during which time evolution of acidic gases (HCl) was observed. The resultant suspension was allowed to cool to room temperature, the volume was reduced to about 5 ml by evaporation under a vacuum at room temperature, after which hexane (20 ml) was added. The dark red-coloured solid formed was recovered by way of filtration, washed with hexane (2×2 ml) and dried under a vacuum at room temperature, 235 mg (yield=69%) of a dark red-coloured solid product corresponding to the complex VCl.sub.2(L2) being obtained.

[0175] Elemental analysis [found (calculated for C.sub.14H.sub.18Cl.sub.2NOV)]: C: 48.99% (49.73%); H: 5.52% (5.37%); N: 3.82% (4.14%); V: 15.52% (15.06%); Cl: 21.19% (20.97%).

[0176] FT-IR (solid state, UATR, cm.sup.−1): 1542; 1465.

[0177] FIG. 11 shows the FT-IR spectrum (solid state, UATR) of the resultant complex VCl.sub.2(L2).

Example 6

Synthesis of VCl.SUB.2.(L3)(thf) [Sample GT-363]

[0178] ##STR00008##

[0179] The vanadium(III) chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3] (560 mg; 3.56 mmol) was introduced into a 50 ml side-arm flask together with a yellow-coloured solution of the ligand having the formula (L3) (675 mg; 3.57 mmol; molar ratio L3/V=1), obtained as described in Example 3, in toluene (20 ml). The resultant mixture, which immediately turned reddish on addition of the vanadium(III) chloride(tris-tetrahydrofuran) [VCl.sub.3(THF).sub.3], was refluxed for 3 hours, during which time evolution of acidic gases (HCl) was observed. The resultant suspension was allowed to cool to room temperature, the volume was reduced to about 10 ml by evaporation under a vacuum at room temperature, after which hexane (20 ml) was added. The dark red-coloured solid formed was recovered by way of filtration, washed with hexane (2×2 ml) and dried under a vacuum at room temperature, 826 mg (yield=75%) of a dark red-coloured solid product corresponding to the complex VCl.sub.2(L3)(thf) being obtained.

[0180] Elemental analysis [found (calculated for C.sub.12H.sub.14Cl.sub.2NOV)]: C: 45.98% (46.48%); H: 22.23% (22.87%); N: 4.05% (4.52%); V: 15.92% (16.43%); Cl: 22.80% (22.87%).

[0181] FT-IR (solid state, UATR, cm.sup.−1): 1539; 1486; 1334.

[0182] FIG. 12 shows the FT-IR spectrum (solid state, UATR) of the resultant complex VCl.sub.2(L3).

Example 7 (MM430)

[0183] 2 ml of 1,3-butadiene, equal to about 1.4 g, were condensed in the cold (−20° C.) in a 25 ml tube. 7.8 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Dry methylaluminoxane (dry MAO) in a solution in toluene (6.3 ml; 1.0×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L1)(thf) (sample GT-298) (1.84 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.68 mg) obtained as described in Example 4. The whole was stirred with a magnetic stirrer at 20° C. for 95 minutes. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.852 g of polybutadiene having a mixed cis/trans/1,2 structure and a 1,4-trans and 1,4-cis unit content of 72.5%: further characteristics of the process and of the resultant polybutadiene are shown in Table 1.

[0184] FIG. 13 shows the FT-IR spectrum of the resultant polybutadiene.

Example 8 (G1304)

[0185] 2 ml of 1,3-butadiene, equal to about 1.4 g, were condensed in the cold (−20° C.) in a 25 ml tube. 7.8 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Methylaluminoxane (MAO) in a solution in toluene (6.3 ml; 1.0×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L1)(thf) (sample GT-298) (1.84 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.68 mg) obtained as described in Example 4. The whole was stirred with a magnetic stirrer at 20° C. for 20 hours. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), 0.427 g of polybutadiene having a mixed cis/trans/1,2 structure and a 1,4-trans and 1,4-cis unit content of 89.4% being obtained: further characteristics of the process and of the resultant polybutadiene are shown in Table 1.

[0186] FIG. 14 shows the FT-IR spectrum of the resultant polybutadiene.

Example 9 (MM433)

[0187] 2 ml of 1,3-butadiene, equal to about 1.4 g, were condensed in the cold (−20° C.) in a 25 ml tube. 7.8 ml of 1,2-dichlorobenzene were then added and the temperature of the resultant solution was adjusted to 20° C. Dry methylaluminoxane (dry MAO) in a solution in 1,2-dichlorobenzene (6.3 ml; 1.0×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L1)(thf) (sample GT-298) (1.84 ml of suspension in 1,2-dichlorobenzene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.68 mg) obtained as described in Example 4. The whole was stirred with a magnetic stirrer at 20° C. for 95 minutes. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.739 g of polybutadiene having a mixed cis/trans/1,2 structure and a 1,4-trans and 1,4-cis unit content of 78.7%: further characteristics of the process and of the resultant polybutadiene are shown in Table 1.

[0188] FIG. 15 shows the FT-IR spectrum of the resultant polybutadiene.

Example 10 (MM316)

[0189] 2 ml of 1,3-butadiene, equal to about 1.4 g, were condensed in the cold (−20° C.) in a 25 ml tube. 7.6 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Dry methylaluminoxane (dry MAO) in a solution in toluene (6.3 ml; 1.0×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L2) (sample GT-301) (2.1 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 4.2 mg) obtained as described in Example 5. The whole was stirred with a magnetic stirrer at 20° C. for 60 minutes. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.988 g of polybutadiene having a mixed cis/trans/1,2 structure and a 1,4-trans and 1,4-cis unit content of 81.0%: further characteristics of the process and of the resultant polybutadiene are shown in Table 1.

[0190] FIG. 16 shows the FT-IR spectrum of the resultant polybutadiene.

Example 11 (G1305)

[0191] 2 ml of 1,3-butadiene, equal to about 1.4 g, were condensed in the cold (−20° C.) in a 25 ml tube. 7.6 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Methylaluminoxane (MAO) in a solution in toluene (6.3 ml; 1.0×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L2) (sample GT-301) (2.1 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 4.2 mg) obtained as described in Example 5. The whole was stirred with a magnetic stirrer at 20° C. for 10 minutes. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.986 g of polybutadiene having a predominantly 1,4-trans structure and a 1,4-trans unit content of 97.0%: further characteristics of the process and of the resultant polybutadiene are shown in Table 1.

[0192] FIG. 17 shows the .sup.1H-NMR and .sup.13C-NMR spectra of the resultant polybutadiene.

Example 12 (MM418)

[0193] 2 ml of 1,3-butadiene, equal to about 1.4 g, were condensed in the cold (−20° C.) in a 25 ml tube. 8.15 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Dry methylaluminoxane (dry MAO) in a solution in toluene (6.3 ml; 1.0×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L3)(thf) (sample GT-363) (1.55 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.1 mg) obtained as described in Example 6. The whole was stirred with a magnetic stirrer at 20° C. for 150 minutes. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.212 g of polybutadiene having a mixed cis/trans/1,2 structure and a 1,4-trans and 1,4-cis unit content of 79.0%: further characteristics of the process and of the resultant polybutadiene are shown in Table 1.

[0194] FIG. 18 shows the FT-IR spectrum of the resultant polybutadiene.

Example 13 (MM417)

[0195] 2 ml of 1,3-butadiene, equal to about 1.4 g, were condensed in the cold (−20° C.) in a 25 ml tube. 8.15 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Methylaluminoxane (MAO) in a solution in toluene (6.3 ml; 1.0×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L3)(thf) (sample GT-363) (1.55 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.1 mg) obtained as described in Example 6. The whole was stirred with a magnetic stirrer at 20° C. for 72 hours. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.291 g of polybutadiene having a mixed cis/trans/1,2 structure and a 1,4-trans and 1,4-cis unit content of 89.1%: further characteristics of the process and of the resultant polybutadiene are shown in Table 1.

[0196] FIG. 19 shows the FT-IR spectrum of the resultant polybutadiene.

Example 14 (MM434)

[0197] 2 ml of 1,3-butadiene, equal to about 1.4 g, were condensed in the cold (−20° C.) in a 25 ml tube. 8.15 ml of 1,2-dichlorobenzene were then added and the temperature of the resultant solution was adjusted to 20° C. Dry methylaluminoxane (dry MAO) in a solution in 1,2-dichlorobenzene (6.3 ml; 1.0×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L3)(thf) (sample GT-363) (1.55 ml of suspension in 1,2-dichlorobenzene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.1 mg) obtained as described in Example 6. The whole was stirred with a magnetic stirrer at 20° C. for 95 minutes. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.340 g of polybutadiene having a mixed cis/trans/1,2 structure and a 1,4-trans and 1,4-cis unit content of 73.2%: further characteristics of the process and of the resultant polybutadiene are shown in Table 1.

[0198] FIG. 20 shows the FT-IR spectrum of the resultant polybutadiene.

Example 15 (G1316)

[0199] 2 ml of isoprene equal to about 1.36 g were introduced into a 25 ml tube. 7.8 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Methylaluminoxane (MAO) in a solution in toluene (6.3 ml; 1×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L1)(thf) (sample GT-298) (1.84 ml of suspension in toluene ata concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.68 mg) obtained as described in Example 4. The whole was stirred with a magnetic stirrer at 20° C. for 24 hours. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.438 g of polyisoprene having a predominantly 1,4-cis structure and a 1,4-cis unit content of 91.3%: further characteristics of the process and of the resultant polyisoprene are shown in Table 2.

[0200] FIG. 21 shows the FT-IR spectrum of the resultant polyisoprene.

[0201] FIG. 22 shows the DSC diagram of the resultant polyisoprene.

[0202] FIG. 23 shows the .sup.1H-NMR and .sup.13C-NMR spectra of the resultant polyisoprene.

Example 16 (MM333)

[0203] 2 ml of isoprene equal to about 1.36 g were introduced into a 25 ml tube. 7.8 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Dry methylaluminoxane (dry MAO) in a solution in toluene (6.3 ml; 1×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L1)(thf) (sample GT-298) (1.84 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.68 mg) obtained as described in Example 4. The whole was stirred with a magnetic stirrer at 20° C. for 60 minutes. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.565 g of polyisoprene having a mixed cis/trans/3,4 structure and a 1,4-trans and 1,4-cis unit content of 83.3%: further characteristics of the process and of the resultant polyisoprene are shown in Table 2.

[0204] FIG. 24 shows the FT-IR spectrum of the resultant polyisoprene.

[0205] FIG. 25 shows the DSC diagram of the resultant polyisoprene.

[0206] FIG. 26 shows the .sup.1H-NMR and .sup.13C-NMR spectra of the resultant polyisoprene.

Example 17 (G1315)

[0207] 2 ml of isoprene equal to about 1.36 g were introduced into a 25 ml tube. 7.6 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Methylaluminoxane (MAO) in a solution in toluene (6.3 ml; 1×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L2) (sample GT-301) (2.1 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 4.2 mg) obtained as described in Example 5. The whole was stirred with a magnetic stirrer at 20° C. for 24 hours. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.340 g of polyisoprene having a predominantly 1,4-cis structure and a 1,4-cis unit content of 90.9%: further characteristics of the process and of the resultant polyisoprene are shown in Table 2.

[0208] FIG. 27 shows the DSC diagram of the resultant polyisoprene.

[0209] FIG. 28 shows the .sup.1H-NMR and .sup.13C-NMR spectra of the resultant polyisoprene.

Example 18 (G1318)

[0210] 2 ml of isoprene equal to about 1.36 g were introduced into a 25 ml tube. 7.6 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Dry methylaluminoxane (dry MAO) in a solution in toluene (6.3 ml; 1×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L2) (sample GT-301) (2.1 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 4.2 mg) obtained as described in Example 5. The whole was stirred with a magnetic stirrer at 20° C. for 60 minutes. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.225 g of polyisoprene having a mixed cis/trans/3,4 structure and a 1,4-trans and 1,4-cis unit content of 84.3%: further characteristics of the process and of the resultant polyisoprene are shown in Table 2.

[0211] FIG. 29 shows the DSC diagram of the resultant polyisoprene.

[0212] FIG. 30 shows the .sup.1H-NMR and .sup.13C-NMR spectra of the resultant polyisoprene.

Example 19 (MM427)

[0213] 2 ml of isoprene equal to about 1.36 g were introduced into a 25 ml tube. 8.15 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Methylaluminoxane (MAO) in a solution in toluene (6.3 ml; 1×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L3)(thf) (sample GT-363) (1.55 ml of suspension in toluene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.1 mg) obtained as described in Example 6. The whole was stirred with a magnetic stirrer at 20° C. for 21 hours. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.239 g of polyisoprene having a predominantly 1,4-cis structure and a 1,4-cis unit content of 86.2%: further characteristics of the process and of the resultant polyisoprene are shown in Table 2.

[0214] FIG. 31 shows the FT-IR spectrum of the resultant polyisoprene.

Example 20 (MM428)

[0215] 2 ml of isoprene equal to about 1.36 g were introduced into a 25 ml tube. 8.15 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Dry methylaluminoxane (dry MAO) in a solution in toluene (6.3 ml; 1×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L3)(thf) (sample GT-363) (1.55 ml of suspension in toluene ata concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.1 mg) obtained as described in Example 6. The whole was stirred with a magnetic stirrer at 20° C. for 21 hours. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.271 g of polyisoprene having a mixed cis/trans/3,4 structure and a 1,4-trans and 1,4-cis unit content of 81.5%: further characteristics of the process and of the resultant polyisoprene are shown in Table 2.

[0216] FIG. 32 shows the FT-IR spectrum of the resultant polyisoprene.

Example 21 (MM429)

[0217] 2 ml of isoprene equal to about 1.36 g were introduced into a 25 ml tube. 8.15 ml of toluene were then added and the temperature of the resultant solution was adjusted to 20° C. Dry methylaluminoxane (dry MAO) in a solution in 1,2-dichlorobenzene (6.3 ml; 1×10.sup.−2 moles, equal to about 0.58 g) was then added, followed by the complex VCl.sub.2(L3)(thf) (sample GT-363) (1.55 ml of suspension in 1,2-dichlorobenzene at a concentration of 2 mg/ml; 1×10.sup.−5 moles, equal to about 3.1 mg) obtained as described in Example 6. The whole was stirred with a magnetic stirrer at 20° C. for 20 hours. The polymerisation was then quenched by adding 2 ml of methanol containing a few drops of hydrochloric acid. The resultant polymer was then coagulated by adding 40 ml of a methanolic solution containing 4% of Irganox® 1076 antioxidant (Ciba), there being obtained 0.813 g of polyisoprene having a mixed cis/trans/3,4 structure and a 1,4-trans and 1,4-cis unit content of 85.0%: further characteristics of the process and of the resultant polyisoprene are shown in Table 2.

[0218] FIG. 33 shows the FT-IR spectrum of the resultant polyisoprene.

TABLE-US-00001 TABLE 1 Polymerisation of 1,3-butadiene with catalytic systems comprising oxo-nitrogenated vanadium complexes Time Conversion 1,4-cis 1,4-trans 1.2 M.sub.w Example (minutes) (%) (%) (%) (%) (g × mol.sup.−1) M.sub.w/M.sub.n  7 95 60.9 46.1 26.4 27.4 302950 2.2  8 1200 30.5 51.8 37.6 10.6 326603 1.9  9.sup.(a) 95 52.9 61.8 16.9 21.3 298700 2.0 10 60 70.6 23.5 57.5 18.2 269800 1.9 11 10 70.4 0 97 3 954730 1.6 12 150 15.1 43.2 35.8 21.0 315400 2.0 13 4320 20.8 68.8 20.3 10.9 395600 1.8 14.sup.(a) 95 24.3 37.2 36.0 26.8 287800 2.1 .sup.(a)polymerisation solvent 1,2-dichlorobenzene.

TABLE-US-00002 TABLE 2 Polymerisation of isoprene with catalytic systems comprising oxo-nitrogenated vanadium complexes Time Conversion 1,4-cis 1,4-trans 3.4 M.sub.w Example (hours) (%) (%) (%) (%) (g × mol.sup.−1) M.sub.w/M.sub.n 15 24 32.2 91.3 0 8.7 122500 1.8 16 1 41.5 32.2 51.1 16.7 98700 1.9 17 24 25.0 90.9 0 9.1 151700 2.0 18 1 16.5 28.2 56.1 15.7 115600 1.9 19 21 17.6 86.2 0 13.8 134900 2.0 20 21 19.9 31.5 50.0 31.5 118750 1.9 21.sup.(a) 20 59.8 36.7 48.3 15.0 135200 2.1 .sup.(a)polymerisation solvent 1,2-dichlorobenzene.