Zincocenes as Mild Cyclopentadienyl Transfer Reagents toward Rhodium(I) Olefin Precursors. Facile Synthesis of (η⁵-Cp′)Rh(olefin)₂Compounds

The Rh(I) cyclopentadienyl olefin compounds [(η5-C5Me4R)Rh(olefin)2] (R = CMe3, SiMe3, SiMe2CMe3; olefin = C2H4, C2H3SiMe3) are readily prepared from the corresponding [RhCl(olefin)2]2 and zincocene, [Zn(C5Me4R)2], precursors. The new compounds undergo hydrogen/deuterium exchange at the olefinic sites in deuterated benzene, at a rate dependent on the cyclopentadienyl substituents.