Complexes of copper(i) and silver(i) with bis(methimazolyl)borate and dihydrobis(2-mercaptothiazolyl)borate ligands

Abstract

The complexes [Cu(Bm^Me)]₃·0.77C₄H₈O (1), [(Bm^Me)Ag(PPh₃)] (2) and [M{κ³-H(μ-H)B(tiaz)₂}(PPh₃)] (M= Cu (3), Ag (4); Bm^Me = bis(2-mercapto-1-methylimidazolyl)borate, H₂B(tiaz)₂ = dihydrobis(2-mercaptothiazolyl)borate) have been prepared and characterised by X-ray crystallographic and spectroscopic methods. The presence of M⋯H–B interactions in these species has been investigated using infrared spectroscopy and crystallography. In [Cu(Bm^Me)]₃, the triangular array of three trigonal-planar copper atoms is coordinated by three chelating and bridging (Bm^Me)⁻ ligands, and has an unusual, highly unsymmetrical arrangement with one short Cu–Cu distance; this is the first structurally authenticated Bm^Me complex with a nuclearity greater than two. In complexes 2–4, the metal atom is found in a distorted trigonal-planar geometry, bound by a terminal phosphine ligand and two sulfur atoms of a chelating ligand, supplemented by an M⋯H–B interaction, which appears to be a common feature in the coordination chemistry of the (Bm^Me)⁻ and [H₂B(tiaz)₂]⁻ ligands; compounds 1–4 are the first reported complexes of copper(I) and silver(I) with any bis(2-mercaptoimidazolyl)borate ligand or with H₂B(tiaz)₂.