Valence Interconversion of Octahedral Nickel(II/III/IV) Centers

We discovered that three oxidation states (+II, +III, +IV) of an octahedral nickel center were all stabilized in a newly prepared RhNiRh trinuclear complex, [Ni{Rh(apt)₃}₂]n+, in which the nickel center is bound by six thiolato donors from two redox-inert fac-[RhIII(apt)₃] octahedral units. The three oxidation states of the octahedral nickel center were fully characterized by single-crystal X-ray crystallography, in addition to spectroscopic, electrochemical, and magnetic measurements. The three oxidation states were interconvertible, and the conversion was accompanied by changes in color, magnetism, and Jahn-Teller distortion.