A Ni(I)Fe(II) analogue of the Ni-L state of the active site of the [NiFe] hydrogenases

[Ni(L-1)Fe((BuNC)-Bu-t)(4)](PF6)(2) is a robust (NiFeII)-Fe-II complex that undergoes a reversible one-electron reduction. Spectroscopic and theoretical studies show that [Ni(L-1)Fe((BuNC)-Bu-t)(4)](+) is an unprecedented (NiFeII)-Fe-I species that reproduces the electronic configuration of the Ni-L state of the [NiFe] hydrogenases.