Low-coordinate germylene and stannylene heterocycles featuring sterically tunable bis(amido)silyl ligands

Abstract

A series of monomeric heterocyclic metallylenes [{(i)Pr(2)Si(NR)(2)}M:] (M = Ge and Sn; R = Dipp = 2,6-(i)Pr(2)C(6)H(3) or SiPh(3)) have been prepared. Preliminary atom-transfer chemistry involving the new low-valent germylenes with the chalcogen sources Me(3)NO and S(8) yielded the corresponding dimeric oxo- and sulfido complexes (e.g., [{(i)Pr(2)Si(NDipp)(2)}Ge(μ-E)](2); E = O and S). Structural analyses of the metallylenes and their oxidized products reveal that incorporation of the umbrella-shaped triarylsilyl groups (SiPh(3)) within the NSiN chelate confers additional steric protection about the group 14 centers relative to a Dipp group. The inclusion of sterically modifiable -SiAr(3) (Ar = aryl) units as part of a bis(amido) ligand array represents a new approach in this field and holds considerable promise with regard to attaining increasingly higher degrees of steric bulk.