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

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journal contribution
posted on 08.12.2008, 00:00 authored by Sylvain Gatard, Chun-Hsing Chen, Bruce M. Foxman, Oleg V. Ozerov
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(SPri2) (1) reacted with certain silyl halides with formation of (PNP)Rh(Silyl)(Hal) and release of SPri2. The reactions with 1.1 equiv of Me3Si-I, Cl3Si-Cl, or MeCl2Si-Cl proceeded to completion, the reactions with 1.1 equiv of Me2ClSi-Cl or Me3Si-Br produced an equilibrium mixture of (PNP)Rh(Silyl)(Hal) and (PNP)Rh(SPri2) (1), and the reaction with Me3Si-Cl did not proceed at all. (PNP)Rh(SiMe3)(Cl) was instead prepared via the reaction of (PNP)Rh(Me)(CH2Ph) with Me3Si-Cl, which proceeds with concomitant elimination of ethylbenzene. The reaction of (PNP)Rh(SPri2) (1) with Me2SiHCl led to the exclusive formation of (PNP)Rh(SiMe2Cl)(H) (14), containing a borderline Si···H contact. (PNP)Rh(SPri2) (1) and (PNP)Rh(SiMe2Cl)(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 SPri2 or Me2SiCl2.