The synthesis and structural characterization of bis(mercaptoimidazolyl)(pyrazolyl)hydroborato and tris(mercaptoimidazolyl)hydroborato complexes of thallium(I) and thallium(III)

The bis(mercaptoimidazolyl)(pyrazolyl)hydroborato and tris(mercaptoimidazolyl)hydroborato ligands, [pzBmMe]− and [TmPh]−, have been used to prepare complexes of both thallium(I) and thallium(III), namely [pzBmMe]Tl, [pzBmMe]TlMe2, {[TmPh]2Tl}2 and {[TmPh]2Tl}[ClO4]. For example, reaction of [pzBmMe]Tl with Me2TlCl yields [pzBmMe]TlMe2, while reaction of [TmPh]Li with Tl(ClO4)3 yields {[TmPh]2Tl}[ClO4]. [pzBmMe]TlMe2, {[TmPh]2Tl}2 and {[TmPh]2Tl}[ClO4] have been structurally characterized by X-ray diffraction. Interestingly, for the monomeric thallium(III) derivatives, the pyrazolyl group does not coordinate to the thallium center in the dimethyl complex [pzBmMe]TlMe2, which is therefore fur-coordinate, whereas all the mercaptoimidazolyl groups coordinate to thallium in {[TmPh]2Tl}+, thereby resulting in a six-coordinate octahedral geometry.