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(mercaptoimidazol yl)hydroborato ligands, [pzBm(Me)](-) and [Tm-Ph](-), have been used to pre pare complexes of both thallium(I) and thallium(III), namely [pzBm(Me)]Tl, [pzBm(Me)]TlMe2, {[Tm-Ph](2)Tl}(2) and {[Tm-Ph](2)Tl}[ClO4]. For example, r eaction of [pzBm(Me)]Tl with Me2TlCl yields [pzBm(Me)]TlMe2, while reaction of [Tm-Ph]Li with Tl(ClO4)(3) yields {[Tm-Ph](2)Tl}[ClO4]. [pzBm(Me)]TlMe2 , {[Tm-Ph](2)Tl}(2) and {[Tm-Ph](2)Tl}[ClO4] have been structurally charact erized by X-ray diffraction. Interestingly, for the monomeric thallium(III) derivatives, the pyrazolyl group does not coordinate to the thallium cente r in the dimethyl complex [pzBm(Me)]TlMe2, which is therefore four-coordina te, whereas all the mercaptoimidazolyl groups coordinate to thallium in {[T m-Ph](2)Tl}(+), thereby resulting in a six-coordinate octahedral geometry.