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

Addition of o-Ph2PC6H4CHdouble bond; length as m-dashN-2,6-iPr2C6H3 (1) to [RhCl(coe)2]2 (coe = cis-cycloctene) gave several new iminophosphino rhodium(I) complexes including [Rh(κ2-o-Ph2PC6H4CHdouble bond; length as m-dashN-2,6-iPr2C6H3)(μ-Cl)]2 (2). Addition of 1 to Rh(acac)(coe)2 (acac = acetylacetonato) gave [Rh(acac)(κ2-o-Ph2PC6H4CHdouble bond; length as m-dashN-2,6-iPr2C6H3)] (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.