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

Abstract

The bis(mercaptoimidazolyl)(pyrazolyl)hydroborato and tris(mercaptoimidazolyl)hydroborato ligands, [pzBm^Me]⁻ and [Tm^Ph]⁻, have been used to prepare complexes of both thallium(I) and thallium(III), namely [pzBm^Me]Tl, [pzBm^Me]TlMe₂, {[Tm^Ph]₂Tl}₂ and {[Tm^Ph]₂Tl}[ClO₄]. For example, reaction of [pzBm^Me]Tl with Me₂TlCl yields [pzBm^Me]TlMe₂, while reaction of [Tm^Ph]Li with Tl(ClO₄)₃ yields {[Tm^Ph]₂Tl}[ClO₄]. [pzBm^Me]TlMe₂, {[Tm^Ph]₂Tl}₂ and {[Tm^Ph]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 [pzBm^Me]TlMe₂, which is therefore fur-coordinate, whereas all the mercaptoimidazolyl groups coordinate to thallium in {[Tm^Ph]₂Tl}⁺, thereby resulting in a six-coordinate octahedral geometry.