Semirigid Pincer-Like SiPSi Ligands: Classical Versus Nonclassical Coordination Modes at Ru, Rh, Ir, and Pt

Abstract While the majority of the reported transition metal systems bonded to silylphosphines have focused on the combination of one Si with either one, two or three phosphorus atoms, semirigid multi-silyl phosphine designs remain largely unexplored. This chapter focuses on a pincer-like silylphosphine system, SiPSi , in which the flexibility of the ligand is increased by adding two extra methylene groups on the otherwise rigid phosphine. These changes furnish upon complexation either non classical agostic M-η 2 -(Si-H) bonds or proceed via oxidative addition to κ 1 -Si-M-H core structures. The semirigid pincer-like SiPSi ligand [Ph P ( o -C 6 H 4 -CH 2 Si Me 2 H) 2 ] and its related tetradentade SiPSi-Si ligand [ P ( o -C 6 H 4 -CH 2 Si Me 2 H) 3 ] can adopt either meridional (Pt) as in pincer complexes or facial (Ru, Rh, Ir) arrangements depending on the choice of ancillary ligands and the metal. Full oxidative addition of the Si-H bonds or non classical coordination modes can be achieved.