C-C σ complexes of rhodium

Abstract

In this article, the complexes [Rh(Binor-S′)(PR3)] [BArF4] (R = iPr, Cy, C5H 9) are described. A combination of x-ray crystallography, NMR spectroscopy, density functional theory, and "atoms in molecules" calculations unequivocally demonstrates that the complexes contain rare examples of metal⋯C-C agostic interactions. Moreover, they are fluxional on the NMR time scale, undergoing rapid and reversible C-C activation. Kinetic data and calculations point to a bismetallacyclobutane, Rh(V), intermediate. © 2007 by The National Academy of Sciences of the USA.