Discrete Mononuclear and Dinuclear Nickel(II) Complexes of Alkane- and Areneselenolates: Syntheses, Structures, and Properties of (Et4N)2[Ni2(Se(CH2)3Se)3], (Ph4P)2[Ni(SePh)4], and (Ph4P)2[Ni2(μ-2,4,6-(Me)3C6H2Se)2(2,4,6-(Me)3C6H2Se)4]·8CH3CN

Abstract

Reaction of the alkanediselenolate (Et4N)2(Se(CH2)3Se) with NiCl2·6H2O in ethanol/acetonitrile mixture affords the dimeric complex (Et4N)2[Ni2(Se(CH2)3Se)3] (1), in which the coordination geometry around each Ni(II) center is square planar. In contrast, reaction of the areneselenolate PhSe- with NiCl2·6H2O in acetonitrile gives rise to (Ph4P)2[Ni(SePh)4] (2), which comprises a distorted tetrahedral NiSe4 chromophore. When the bulky areneselenolate 2,4,6-(Me)3C6H2Se- is used, the same reaction affords the dimeric complex (Ph4P)2[Ni2(μ-2,4,6-(Me)3C6H2Se)2(2,4,6-(Me)3C6H2Se)4]·8CH3CN (3), which contains square planar NiSe4 chromophores. Unfavorable steric interactions among o-methyl groups, nickel, and the Se atoms do not allow a tetrahedral coordination sphere around nickel in 3. Complex 1 crystallizes in the orthorhombic space group Pna21 with a = 16.645(3) A, b = 20.214(6) A, c = 11.428(3) A, V = 3846(3) A3, and Z = 4. The structure of 1 was refined to R = 7.34% on the basis of 1694 (I > 4σ(I)) data. Comp...