Unusual reactivity of a nickel N-heterocyclic carbene complex: tert-butyl group cleavage and silicone grease activation

Reaction lubrication? The reaction between [Ni(1,5-cod)2] (cod=cyclooctadiene) and 1,3-bis-tert-butylimidazol-2-ylidene in the presence of silicone grease affords the siloxane bridged dimer [{Ni[C(NtBuCH) 2][O(Me2SiOSiMe2)-µ-O]}2]. In a greaseless apparatus, the same reaction yields the dimer 1 (see structure), via two structurally characterized intermediates.