Facile formation of rare terminal chalcogenido germanium complexes with alkylamidinates as supporting ligands

The first characterized amidinate complexes of Ge have been prepared using alkylamidinates as ancillary ligands. Spectroscopic and structural characterization of the two complexes, (CyNC(Me)NCy)(2)Ge-II (1) and (CyNC(Bu-t)NCy)(2)Ge-II (2) (Cy = cyclohexyl), revealed that the Ge coordination geometry is distorted tetrahedral in which one of the vertices is occupied by a lone pair of electrons. Both 1 and 2 exhibited one bidentate and one monodentate (''dangling'') ligand. Rapid oxidative addition of chalcogen atom sources (styrene sulfide and Se) to these complexes resulted in a series of rare terminal chalcogenido complexes with the formulas (CyNC(R)NCy)(2)Ge=Ch [R = Me, Ch = S (3), Se(4); R = Bu-t, Ch = S (5), Se(6)]. The spectroscopic data and X-ray structure of 6 revealed a terminal Ge=Se complex; Mixed amidinato-amido analogues were similarly obtained. For example, [(CyNC(R)NCy)Ge-II[N(SiMe3)(2)] (R = Me, Bu-t) react to yield the corresponding terminal chalcogenido complexes. In the case of [(CyNC(Me)NCy)Ge-II[N(SiMe3)(2)]Se (10), a crystallographic study confirmed the presence of a terminal Ge=Se bond.