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

Flexible, chelating bis(NHC) ligand 2 , able to accommodate both cis ‐ and trans ‐coordination modes, was used to synthesize ( 2 )Ni(η 2 ‐cod), 3 . In reaction with GeCl 2 , it produced ( 2 )NiGeCl 2 , 4 , featuring a T‐shaped Ni 0 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 GeCl 2 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) 2 Ni(cod) complexes 9 and 10 , as well as (NHC) 2 GeCl 2 derivative 11 , incorporating ligands that cannot accommodate a wide bite angle, failed to produce isolable Ni–Ge complexes. The isolation of ( 2 )Ni(η 2 ‐Py), 12 , provides further evidence for the reluctance of the ( 2 )Ni 0 fragment to act as a σ‐Lewis acid.