Studies on the reaction between bis((trimethylsilyl)cyclopentadienyl)niobium trihydride and styrene

Article abstract of DOI:10.1021/om00019a036

Bis((trimethylsilyl)cyclopentadienyl)niobium hydride styrene, Nb(η⁵-C₅H₄SiMe₃) ₂(H)(η²-PhCH=CH₂) (3), has been prepared both from the reaction of Nb(η⁵-C₅H₄SiMe₃) ₂H₃ (1) with styrene and from that of Nb(η⁵-C₅H₄SiMe₃)Cl₂ (2) with PhCH₂CH₂MgBr. The first method gives rise to two isomeric products (endo, where the olefinic substituent is central, and exo, with the olefinic substituent lateral in the equatorial plane), while the latter leads exclusively to the endo isomer. The mechanism of the formation of 3 is discussed in terms of a model which implies a consecutive reaction with a reversible step and a first-order rate dependence with respect to 1. Finally, the kinetics of the olefin-hydride insertion have been studied by ¹H NMR spectroscopy using coalescence techniques.