Novel rhodium complexes containing a bulky iminophosphine ligand and their use as catalysts for the hydroboration of vinylarenes

Abstract

Addition of o-Ph 2PC 6H 4CH N-2,6- i Pr 2C 6H 3 ( 1) to [RhCl(coe) 2] 2 (coe = cis-cycloctene) gave several new iminophosphino rhodium(I) complexes including [Rh(κ 2- o-Ph 2PC 6H 4CH N-2,6- i Pr 2C 6H 3)(μ-Cl)] 2 ( 2). Addition of 1 to Rh(acac)(coe) 2 (acac = acetylacetonato) gave [Rh(acac)(κ 2- o-Ph 2PC 6H 4CH N-2,6- i Pr 2C 6H 3)] ( 3) in yields of up to 75%. Complex 3 has been examined for its ability to catalyze the hydroboration of a series of vinyl arenes. Reactions using catecholborane and pinacolborane seem to proceed largely through a dehydrogenative borylation mechanism to give a number of boronated products.