A Nickel Complex Containing a Pyramidalized, Ambiphilic Pincer Germylene Ligand.

Reaction of N-heterocyclic carbene (NHC)-stabilized PGeP-type germylene Ge{o-(PiPr )C H } ⋅ IiPr (1) ( IiPr=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) with Ni(cod) gave pincer germylene complex NiGe{o-(PiPr )C H } (2), in which the Ge center of 2 is significantly pyramidalized. Theoretical calculation on 2 predicted the ambiphilicity of the germanium center, which was confirmed by reactivity studies. Thus, complex 2 reacted with both Lewis base IMe ( IMe=1,3,4,5-tetramethylimidazol-2-ylidene) and Lewis acid BH ⋅SMe at the germanium center to afford the adducts NiGe{o-(PiPr )C H } ⋅ IMe (3) and NiGe{o-(PiPr )C H } ⋅BH (4), respectively. Furthermore, the former was slowly converted to dinuclear complex Ni [Ge{o-(PiPr )C H } ] ( IMe) (5) at room temperature. Complex 5 can be regarded as a dimer of the IMe analog of 2 with a Ni-Ge-Ge-Ni linkage.