Synthesis and structural studies of rhenium(I) tricarbonyl complexes with thione containing chelators

Abstract

Sodium dihydrobis(2-mercaptothiazolyl)borate, Na[H 2B(tiaz) 2], reacts with (NEt 4) 2[Re(CO) 3Br 3] in water to afford fac-[Re{κ 3-H(μ-H)B(tiaz) 2}(CO) 3] ( 1). In a similar manner, treatment of the same Re(I) starting material with bis(2-mercaptoimidazolyl)methane, H 2C(tim Me) 2, yields fac-[ReBr{κ 2-H 2C(tim Me) 2}(CO) 3] ( 2). The organometallic complexes 1 and 2 have been characterized by IR, 1H and 13C NMR spectroscopy, and also by X-ray crystallographic analysis. X-ray diffraction analysis revealed the presence of a short B–H⋯Re interaction in the case of 1, and the absence of C–H⋯Re interactions in the crystal structure of 2. For both compounds the rhenium atom adopts a slightly distorted octahedral coordination with a facial arrangement of the carbonyl ligands. The three remaining coordination positions are occupied by the two thione sulfur atoms from the anchor ligands, and by an agostic hydride ( 1) or a bromide ligand ( 2). Compound 1 is highly stable either in the solid state or in solution. In particular, its B–H⋯Re interaction is retained in solution, even in coordinating solvents, namely acetonitrile, dimethylsulfoxide and tetrahydrofuran. Unlike 1, compound 2 is only moderately stable in acetonitrile, undergoing a slow release of the bis(2-mercaptoimidazolyl)methane.