A Nickel Complex Containing a Pyramidalized, Ambiphilic Pincer Germylene Ligand

: Reaction of N-heterocyclic carbene (NHC)-stabilized PGeP-type germylene Ge{o-(PiPr2 )C6 H4 }2 ⋅Me IiPr (1) (Me IiPr=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) with Ni(cod)2 gave pincer germylene complex Ni[Ge{o-(PiPr2 )C6 H4 }2 ](Me IiPr) (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 Me IMe (Me IMe=1,3,4,5-tetramethylimidazol-2-ylidene) and Lewis acid BH3 ⋅SMe2 at the germanium center to afford the adducts Ni[Ge{o-(PiPr2 )C6 H4 }2 ⋅Me IMe](Me IiPr) (3) and Ni[Ge{o-(PiPr2 )C6 H4 }2 ⋅BH3 ](Me IiPr) (4), respectively. Furthermore, the former was slowly converted to dinuclear complex Ni2 [Ge{o-(PiPr2 )C6 H4 }2 ]2 (Me IMe)2 (5) at room temperature. Complex 5 can be regarded as a dimer of the Me IMe analog of 2 with a Ni-Ge-Ge-Ni linkage.