Syntheses and structures of diorgano(halo- orpseudohalo-)(1,3-dithiole-2-thione-4,5-dithiolato)-stannates (1-), [Q][RSnX(dmit)] (Q=onium cation; X=halide orpseudohalide)

Ionic compounds, Q] R₂SnX(dmit)]dmit=1,3-dithiole-2-thione-dithiolate; Q=1,4-dimethylpyridinium or tetraalkylammonium; R=Phor alkyl; X=Cl, Br, I, NCS, NCSe, or N₃] have been obtained by (a) from R₂SnX₂ and Q]₂Zn(dmit)₂] in the presence of excess QX,(b) from halide exchange reactions in acetone solution between Q] R₂SnCl(dmit)]and a halide or pseudohalide source, or (c) by addition of QX to R₂Sn(dmit)]. Crystalstructure determinations of NEt₄] Ph₂SnI(dmit)] and 1,4-Me₂pyridiniuml Ph₂SnBr(dmit)] as well as of the mixed halides, 1a, 1b, 4a, 2] Ph₂SnCl_nI₁₋n(dmit)] (n=0.57, 0.42 or0.22), indicated that the tin atoms have distorted trigonal bipyramidal geometries in the anions,with the X ligand and a dithiolato atom in the axial sites. The R₂SnX(dmit)]⁻ anions remain essentially intact in organic solvents, but lose X⁻ on extractionwith H₂O to give the neutral species, R₂Sn(dmit).