title: Expanding the steric coverage offered by bis(amidosilyl) chelates: isolation of low-coordinate N-heterocyclic germylene complexes.
abstract: The synthesis and coordination chemistry of a series of dianionic bis(amido)silyl and bis(amido)disilyl, [NSiN] and [NSiSiN], chelates with N-bound aryl or sterically modified triarylsilyl (SiAr(3)) groups is reported. In order to provide a consistent comparison of the steric coverage afforded by each ligand construct, various two-coordinate N-heterocyclic germylene complexes featuring each ligand set were prepared and oxidative S-atom transfer chemistry was explored. In the cases where clean oxidation transpired, sulfido-bridged centrosymmetric germanium(IV) dimers of the general form [LGe(μ-S)](2) (L = bis(amidosilyl) ligands) were obtained in lieu of the target monomeric germanethiones with discrete Ge═S double bonds. These results indicate that the reported chelates possess sufficient conformational flexibility to allow for the dimerization of LGe═S units to occur. Notably, the new triarylsilyl groups (4-RC(6)H(4))(3)Si- (R = (t)Bu and (i)Pr) still offer considerably expanded degrees of steric coverage relative to the parent congener, -SiPh(3,) and thus the use of substituted triarylsilyl groups within ligand design strategies should be a generally useful concept in advancing low-coordination main group and transition-metal chemistry.
authors.affiliation: Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada, T6G 2G2.
authors.forename: Sean K
authors.initials: SK
authors.lastname: Liew
authors.forename: S M Ibrahim
authors.initials: SM
authors.lastname: Al-Rafia
authors.forename: James T
authors.initials: JT
authors.lastname: Goettel
authors.forename: Paul A
authors.initials: PA
authors.lastname: Lummis
authors.forename: Sean M
authors.initials: SM
authors.lastname: McDonald
authors.forename: Leah J
authors.initials: LJ
authors.lastname: Miedema
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ferguson
authors.forename: Robert
authors.initials: R
authors.lastname: McDonald
authors.forename: Eric
authors.initials: E
authors.lastname: Rivard