Nickel as a Lewis Base in a T‐Shaped Nickel(0) Germylene Complex Incorporating a Flexible Bis(NHC) Ligand

Abstract

AbstractFlexible, chelating bis(NHC) ligand 2, able to accommodate both cis‐ and trans‐coordination modes, was used to synthesize (2)Ni(η2‐cod), 3. In reaction with GeCl2, it produced (2)NiGeCl2, 4, featuring a T‐shaped Ni0 and a pyramidal Ge center. Complex 4 could also be prepared from [(2)GeCl]Cl, 5, and Ni(cod)2, in a reaction that formally involved Ni–Ge transmetalation, followed by coordination of the extruded GeCl2 moiety to Ni. A computational analysis showed that 4 possesses considerable multiconfigurational character and the Ni→Ge bond is formed through σ‐donation from the Ni 4s, 4p, and 3d orbitals to Ge. (NHC)2Ni(cod) complexes 9 and 10, as well as (NHC)2GeCl2 derivative 11, incorporating ligands that cannot accommodate a wide bite angle, failed to produce isolable Ni–Ge complexes. The isolation of (2)Ni(η2‐Py), 12, provides further evidence for the reluctance of the (2)Ni0 fragment to act as a σ‐Lewis acid.