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Keywords:

  • dichalcogens;
  • nickel;
  • oxidation states;
  • platinum;
  • redox ligands

Abstract

A unique heterobimetallic disulfur monoradical, complex 2, with a diamond-shaped {NiS2Pt} core has been synthesized by two-electron reduction of a supersulfido-(nacnac)nickel(II) complex (nacnac=β-diketiminato) with [Pt(Ph3P)22-C2H4)] as a platinum(0) source and isolated in 82 % yield. Strikingly, the results of DFT calculations in accordance with spectroscopic (EPR, paramagnetic NMR) and structural features of the complex revealed that the bonding situation of the S2 ligand is between the elusive “half-bonded” S2 radical trianion (equation image) and two separated S2− ligands. Accordingly, the NiII center is partially oxidized, whereas the PtII site is redox innocent. The complex can be reversibly oxidized to the corresponding Ni,Pt-disulfido monocation, compound 3, with a S[BOND]S single bond, and reacts readily with O2 to form the corresponding superoxonickel(II) and disulfidoplatinum(II) (4) complexes. These compounds have been isolated in crystalline form and fully characterized, including IR and multi-nuclear NMR spectroscopy as well as ESI mass spectrometry. The molecular structures of compounds 24 have been confirmed by single-crystal X-ray crystallography.