A Nickel Complex Containing a Pyramidalized, Ambiphilic Pincer Germylene Ligand. Issue 59 (30th September 2019) - Watanabe, Takahito
Abstract: Reaction of N‐heterocyclic carbene (NHC)‐stabilized PGeP‐type germylene Ge{ o ‐(P i Pr2 )C6 H4 }2 ⋅ Me I i Pr (1 ) ( Me I i Pr=1, 3‐diisopropyl‐4, 5‐dimethylimidazol‐2‐ylidene) with Ni(cod)2 gave pincer germylene complex Ni[Ge{ o ‐(P i Pr2 )C6 H4 }2 ]( Me I i Pr) (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 ‐(P i Pr2 )C6 H4 }2 ⋅ Me IMe]( Me I i Pr) (3 ) and Ni[Ge{ o ‐(P i Pr2 )C6 H4 }2 ⋅BH3 ]( Me I i Pr) (4 ), respectively. Furthermore, the former was slowly converted to dinuclear complex Ni2 [Ge{ o ‐(P i Pr2 )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. Abstract : A nickel pincer germylene complex with a pyramidalized germanium center was synthesized. Theoretical calculation predicted the germanium center to be ambiphilic (electrophilic and nucleophilic), which was confirmed by reactions with Lewis base and Lewis acid. The former adduct was converted to a dinuclear complex with a Ni‐Ge‐Ge‐Ni linkage through Ge−Ge coupling between germylene ligands.