First nickel(II) complexes containing tetrahedral NiO2S2 cores. The molecular structures of Ni[(OPPh2)(SPR2)N]2 (R=Ph, Me)

Ni[(OPR′2)(SPR2)N]2 complexes were obtained in good yields by reacting NiCl2·6H2O and the alkaline salts of the corresponding tetraorganomonothioimidodiphosphinic acids. All compounds were characterized by elemental analysis and IR. The molecular structure of Ni[(OPPh2)(SPR2)N]2 (R=Ph, Me) has been determined by single-crystal X-ray diffractometry. Ni[(OPPh2)-(SPPh2)N]2 (1) crystallizes in the monoclinic space group P21/c (no. 14), and Ni[(OPPh2)(SPMe2)N]2 (2) crystallizes in the triclinic space group P1̄ (no. 2). The crystals of both compounds contain discrete mononuclear molecules. The asymmetric ligands act as monometallic biconnective units which results in a tetrahedral NiO2S2 core.