Cyclometallation of a germylene ligand by concerted metalation-deprotonation of a methyl group.

The reaction of [CH{(CMe)(2,6-iPr2C6H3N)}2]GeCl with LiN(SiMe3)2 was previously reported, which led to the formation of a hetero-fulvene type germylene, [CH{(CMe)(C[double bond, length as m-dash]CH2)(2,6-iPr2C6H3N)}2]Ge through the deprotonation of the C-H bond from the methyl substituents. In this paper, we attempted the analogous reaction with (Dipp)NCMeCHCOMeGeCl using LiN(SiMe3)2 which gave rise to a metathesis product, (Dipp)NCMeCHCOMeGeN(SiMe3)2 (2). However, the reactions of 2 with [M2Cl2(μ-Cl)2(η5-Cp*)2] (M = Rh and Ir) resulted in cyclometallated Rh and Ir complexes through the activation of the C-H bond from the germylene ligand. The complexes were characterized by single crystal X-ray analysis, which authenticated the presence of Ge-Rh and Ge-Ir bonds. DFT studies have been performed to understand the mechanism.