A unique heterobimetallic disulfur monoradical, complex 2, with a diamond-shaped {NiS_2Pt} core has been synthesized by two-electron reduction of a supersulfido-(nacnac)nickel(II) complex (nacnac=β- diketiminato) with [Pt(Ph_3P)_2(η~2-C _2H_4)] 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 S_2 ligand is between the elusive "half-bonded" S_2 radical trianion (S_2 ~(3-)) and two separated S~(2-) ligands. Accordingly, the Ni~(II) center is partially oxidized, whereas the Pt~(II) site is redox innocent. The complex can be reversibly oxidized to the corresponding Ni,Pt-disulfido monocation, compound 3, with a S-S single bond, and reacts readily with O_2 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 2-4 have been confirmed by single-crystal X-ray crystallography.
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