  A diphosphino-nickel-iron dithiolene complex, [Ni(bdt)(dppf)] (bdt =
1,2-benzenedithiolate, dppf = 1,1-bis(diphenylphosphino)ferrocene), has been
recently found to be reasonably active on proton reduction to dihydrogen (J.
Am. Chem. Soc. 2015, 137, 1109). Interestingly, this exceptional complex was
found to be also reactive towards dihydrogen activation as indicated by the
electrochemical investigation. However, a pure nickel dithiolene diphosphine
theoretical mode, excluding the contributions from iron moiety, was applied to
attribute the experimental catalytic observation. We have re-visited the
theoretical approach in details for this [NiFe] catalyst and compared it with
the non-active nickel dithiolene diphosphine complexes. We found that both
nickel and iron moieties in this newly developed complex were imperative for
the observed catalytic per-formance, particularly towards the activation of
dihydrogen.
