On the Electronic Origin of Remarkable Ligand Effects on the Reactivities of [NiL]+ Complexes (L=C6 H5 , C5 H4 N, CN) towards Methane.

The gas-phase reactions of [NiL]+ (L=C6 H5 , C5 H4 N, CN) with methane have been explored by using electrospray-ionization mass spectrometry (ESI-MS) complemented by quantum chemical calculations. Though the phenyl Ni complex [Ni(C6 H5 )]+ exclusively abstracts one hydrogen atom from methane at ambient conditions, the cyano Ni complex [Ni(CN)]+ brings about both H-atom abstraction and ligand exchange to generate [Ni(CH3 )]+ . In contrast, the complex 2-pyridinyl Ni [Ni(C5 H4 N)]+ is inert towards this substrate. The presence of the empty 4s(Ni) orbital dominates the proton-coupled electron transfer (PCET) processes for the investigated systems.