Oxidative Addition Reactions of Silyl Halides with the (PNP)Rh Fragment

The (PNP)Rh fragment, where PNP is the bis( o -diisopropylphosphinophenyl)amide “pincer” ligand, has been shown to undergo a series of silicon−halogen oxidative addition reactions. (PNP)Rh(SPr i 2 ) ( 1 ) reacted with certain silyl halides with formation of (PNP)Rh(Silyl)(Hal) and release of SPr i 2 . The reactions with 1.1 equiv of Me 3 Si-I, Cl 3 Si-Cl, or MeCl 2 Si-Cl proceeded to completion, the reactions with 1.1 equiv of Me 2 ClSi-Cl or Me 3 Si-Br produced an equilibrium mixture of (PNP)Rh(Silyl)(Hal) and (PNP)Rh(SPr i 2 ) ( 1 ), and the reaction with Me 3 Si-Cl did not proceed at all. (PNP)Rh(SiMe 3 )(Cl) was instead prepared via the reaction of (PNP)Rh(Me)(CH 2 Ph) with Me 3 Si-Cl, which proceeds with concomitant elimination of ethylbenzene. The reaction of (PNP)Rh(SPr i 2 ) ( 1 ) with Me 2 SiHCl led to the exclusive formation of (PNP)Rh(SiMe 2 Cl)(H) ( 14 ), containing a borderline Si···H contact. (PNP)Rh(SPr i 2 ) ( 1 ) and (PNP)Rh(SiMe 2 Cl)(Cl) ( 7 ) displayed similar rates in the reaction with PhBr that results in (PNP)Rh(Ph)(Br), presumably via the rate-limiting elimination of either SPr i 2 or Me 2 SiCl 2 .