Narayan Baidya

Mononuclear nickel(II) thiolates of square-planar geometry: syntheses, spectral and redox properties of [Ni(SCH2CH2S)2]2− and [Ni(SCH(CH3)CH(CH3)S)2]2− and the structure of (Ph4P)2[Ni(SCH2CH2S)2]·4H2O

Abstract Reaction of NiCl2·6H2O with excess (> 10 equiv.) dithiolate ligands ethane-1,2-dithiolate (edt2−) and butane-2,3-dithiolate (bdt2−) in water or ethanol affords the mononuclear thiolato complexes [Ni(edt)2]2− and [Ni(bdt)2]2−, respectively. These homoleptic thiolates contain square-planar NiS4 chromophores. The complex (Ph4P)2[Ni(edt)2]·4H2O (3) crystallizes in the monoclinic space group P21/c with a=10.590(2), b=16.299(3), c=14.752(3) A, β=100.20(2)°, V=2506.0(8) A3 and Z=2. The structure was refined to R=3.31% by using 2486 unique data (Fo2>3σ(Fo2)). In DMF solution, [Ni(bdt)2]2− can be oxidized to the nickel(III) complex [Ni(bdt)2]− at an extremely low potential of -0.75 V versus SCE. EPR parameters of [Ni(bdt)2]− suggest a square-planar structure for this nickel (III) thiolate.