Reduction of the R2P-functionalized zirconocene dichlorides [C5Me4(CH2)2PR2] (C5Me5)ZrCl2 (R = Me (1) and Ph (2)) and [C5Me4(CH2)2PMe2][C5Me4(CH2)2PR2]ZrCl2 (R = Me (3) and Ph (4)) with amalgamated magnesium was studied. In the reduction of compounds 1 and 2, intramolecular C-H activation highly selectively afforded the fulvene hydride complexes Zr(H)(η5−C5Me5)[η5:η2(C,P)−(CH2)C5Me3CH2CH2PR2] (R = Me (7), Ph (8)); in the case of compound 2, the aryl hydride Zr(H)(η5:C5Me5)[η5:η1(C)−C5Me4CH2CH2PPh(o−C6H4)] (9) was also formed. The reduction of complexes 3 and 4 gave the ZrII derivatives Zr[η5:η1(P)− C5Me4CH2CH2PMe2]2 (12) and Zr[η5:η1(P)−C5Me4CH2CH2PMe2][η5:η1(P)−C5Me4CH2 CH2PPh2] (14) stabilized by two phosphine groups. The second product in the reduction of compound 4 was the fulvene hydride complex Zr(H)(η5−C5Me4CH2CH2PPh2)[η5:η2(C,P)−(CH2)C5Me3CH2CH2PMe2] (15). The reaction of compound 7 with an excess of MeI resulted selectively in replacement of the hydride ligand by iodide to give the complex ZrI(η5−C5Me5)[η5:η2(C,P)−(CH2)C5Me3CH2CH2PMe2] (10). In contrast, in the reaction of compound 7 with Me2Si(H)Cl, the Zr-CH2 bond underwent cleavage to give the chloride hydride complex Zr(H)Cl(η5−C5Me5)[η5:η1(P)−C5Me3(CH2SiMe2H)CH2CH2PMe2] (11). In the reaction of complex 12 with CO, a phosphine group was replaced by CO to form the complex Zr(CO)(η5−C5Me4CH2CH2PMe2)[η5:η1(P)−C5Me4CH2CH2PMe2] (13). The results obtained were compared with analogous reduction reactions of MeO-, MeS-, and Me2N-functionalized zirconocene dichlorides.

The copolymerization of ethylene with propylene in the liquid propylene initiated by ansa -metallocenes of the C 1 symmetry, rac -[1-(9-η 5 -fluorenyl)-2-(5,6-cyclopenta-2-methyl-1-η 5 -indenyl)ethane]zirconium dichloride and rac -[1-(9-η 5 -fluorenyl)-2-(5,6-cyclopenta-2-methyl-1-η 5 -indenyl)ethane]hafnium dichloride, activated by methylaluminoxane has been studied. Triisobutylaluminum has been used as a cocatalyst. The propylene-ethylene copolymers thus prepared contain 5–60 mol % ethylene units. The reactivity ratios have been measured. In the case of the zirconocene-based catalyst, the molecular mass of the copolymers decreases with an increase in the content of ethylene units. The reverse situation is observed in the case of the hafnocene-based catalytic system. The copolymers are characterized by the low T g values (down to −45°C). Incorporation of a small amount of ethylene units (5 mol %) results in a rise in the elastomeric behavior of the polymers.

Bulk propylene polymerization in the presence of ansa-metallocenes with C-2 and C-1 symmetries has been studied. The catalytic activity, polymerization kinetics, and the molecular weight of polypropylene (PP) depend strongly on catalyst formation conditions. Mixtures of rac and meso isomers of metallocenes make it possible to rapidly produce a high-molecular-weight isotactic PP with high stereoregularity and mechanical characteristics and thus skip the stage of the isolation of pure rac isomer in the catalyst synthesis. The ability of triisobutylaluminum to serve as a cocatalyst is studied for ansa-metallocenes of C-1 symmetry. In this case, the molecular weight of PP is higher, indicating that organoaluminum compounds participate in chain termination reactions. An increase in the reaction temperature results in an increase in the stereoregularity and crystallinity of PP. Polypropylene synthesized using ansa-metallocenes of C-1 symmetry has good elastomeric properties.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The regioselectivity of alkylation of lithium (trimethylsilyl)tetramethylcyclopentadienide C5Me4SiMe3−Li+ was studied by 1H and 13C NMR spectroscopy using its reactions with MeI, MeOTs, ClCH2CH2Br, and ClCH2CH2I in different solvents as representative examples. Sterically non-hindered MeI and MeOTs presumably attack the C atom bonded to the silyl group giving 1,2,3,4,5-pentamethylcyclopentadienylsilane. For bulkier alkyl halides, such as ClCH2CH2Br and ClCH2CH2I, the regioselectivity of alkylation changes to form preferentially gem-dialkyl-substituted cyclopentadienes. The reaction of C5Me4SiMe3−Li+ with formaldehyde affords 1,2,3,4-tetramethylfulvene in a high yield, providing an alternative synthetic approach to a number of ω-functionalized peralkylated cyclopentadienes. The quantum-chemical calculations of the C5Me4SiMe3− anion by the RHF and DFT (RMPW1PW91) methods in the valence-split 6-311+G(d,p) basis set are in good agreement with the experimental data.

Isomeric 1-(fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta [f]-1 H-indenyl) ethanes 1a,b and C1-symmetric metallocenes, viz., rac-1-(η5-fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta [f]-η5-inden-1-yl) ethanezirconium dichloride (9) and rac-1-(η5-fluoren-9-yl)- 2-(2-methyl-5, 6-dihydrocyclopenta [f]η5-inden-1-yl)ethanehafnium dichloride (10), with these ligands were synthesized by modified procedures. The structures of compounds 1b (two crystalline modifications) and 10 were established by X-ray diffraction analysis. The synthesis of polypropylene (PP) in bulk was studied in the presence of polymethylalumoxane-activated metallocenes 9 and 10 in the temperature range of 30–70°C. It was demonstrated that triisobutylaluminum can be used as a cocatalyst. In this case, the molecular weight of PP increases by a factor of ∼2. An increase in the reaction temperature leads to an increase in stereoregularity and crystallinity of PP. The polymer synthesized at high temperatures crystallizes in the γ form. The resulting PP is characterized by a wide range of properties from rigid crystalline thermoplastic to amorphous elastomeric. Samples, which have a high molecular weight and moderate isotacticity, exhibit high elastomeric and durability properties.

The effects of various pathways of the formation of catalytic systems based on the rac -Me 2 SiInd 2 ZrCl 2 metallocene on the activity and properties of polypropylene prepared by the bulk polymerization of propylene were studied in detail. It was found that the conditions of formation of the catalytic system affect not only its activity and the character of kinetic curves but also the molecular weight of the synthesized polymer. Propylene polymerization was studied with the use of a number of bisindenyl derivatives of zirconium, which were mixtures of rac and meso forms that differ in the nature of substituents in the Si bridge or the indenyl ligand. The conclusion was drawn that, with the use of metallocenes as a mixture of rac and meso forms, high-molecular-weight isotactic polypropylene can be prepared with high stereoregularity at a very high rate; thereby, the stage of separation of a pure rac isomer can be excluded in the synthesis of the catalyst.

The new biscyclopentadienyl lutetium complex (η 5 :η 1 -C 5 H 4 CH 2 CH 2 PPh 2 ) 2 LuCl was synthesized by the reaction of LuCl 3 (THF) 3 with lithium (2-diphenylphosphinoethyl)cyclopentadienide. Its behavior in solution was investigated by dynamic NMR spectroscopy. It was shown that the coordination of both phosphino groups to the lutetium center is retained over the whole temperature range studied. The barrier to pseudo-rotation for the trigonal bipyramid, which governs the intramolecular dynamics of this complex, was determined.

Treatment of a mixture of isomeric (2-chloroethyl)-1,2,3,4-tetramethylcyclopentadienes with lithium diphenylphosphide leads to novel 4,5,6,7-tetramethylspiro[2,4]hepta-4,6-diene among the reaction products. The reaction of spiroheptadiene obtained with excess LiPPh2 at elevated temperature affords lithium 5-(2-diphenylphosphinoethyl)-1,2,3,4-tetramethylcyclopentadienide in almost quantitative yield. the regioselectivity of alkylation of the tetramethylcyclopentadienide anion is estimated from quantum-chemical calculations performedab initio for C5Mc4H−. The full charges on the ring carbon atoms are determined within the framework of Bader's theory of atomic fragments in molecules.