ansa-Metallocene derivatives

Abstract

ansa-Metallocene derivatives xxv *. Synthesis, crystal structure and reactions of a tetramethylethano-bridged vanadocene dichloride, (CH3)4C2(CsH4)zVClz

A journey into the electrochemistry of vanadium compounds

“…The tetramethylethano-bridged vanadocene dichloride was investigated a few years later [236], to get information about the nature of alkene polymerization catalysts. Instead, the ring-bridged vanadocene could not be isolated and cyclovoltammetry indicated that this V(II) complex (in contrast to its unbridged counterpart decays within seconds after its formation by electrochemical reduction of its chloro derivative.…”

Ansa-vanadocene complexes with short interannular bridges

“…The Cp-V bond distances in chloride derivative 3 [1.9650 (9) [20] and are shorter than in ring-substituted compounds (RC 5 - [25,26]. The bromide compound (4) has the Cg-V bond lengths [1.9574(12) Å ] barely shorter than compound 3.…”

“…Previously some efficient routes for preparation of ansavanadocene complexes were developed by Brintzinger et al [20][21][22]. Such studies were focused particularly on the catalytic properties of ansa-metallocenes toward polymerization of a-olefins.…”

ChemInform Abstract: Boron‐Bridged Group‐4 ansa‐Metallocene Complexes

“…Surprisingly, when either III or the related tert-butyl isocyanide complex are combined with an equimolar amount of B(C 6 F 5 ) 3 in CD 2 Cl 2 , only partial abstraction of the Lewis base adduct (30Ϫ37%) by B(C 6 F 5 ) 3 from the phenylborylidene bridge is observed by 1 H and 19 F NMR spectroscopy at 273 K. [47] We expected the boron atom of the phenylborylidene bridge to have an electrophilicity more comparable to that of BPh 3 based on its substitution. Surprisingly, when either III or the related tert-butyl isocyanide complex are combined with an equimolar amount of B(C 6 F 5 ) 3 in CD 2 Cl 2 , only partial abstraction of the Lewis base adduct (30Ϫ37%) by B(C 6 F 5 ) 3 from the phenylborylidene bridge is observed by 1 H and 19 F NMR spectroscopy at 273 K. [47] We expected the boron atom of the phenylborylidene bridge to have an electrophilicity more comparable to that of BPh 3 based on its substitution.…”