Rhenium(III) and technetium(III) complexes with 2-mercapto-1,3-azole ligands and X-ray crystal structures

Reactions of labile [MCl3(PPh3)2(NCMe)] (M = Tc, Re) precursors with 1H-benzoimidazole-2-thiol (H2L1), 5-methyl-1H-benzoimidazole-2-thiol (H2L2) and 1H-imidazole-2-thiol (H2L3), in the presence of PPh3 and [AsPh4]Cl gave a new series of trigonal bipyramidal M(III) complexes [AsPh4]{[M(PPh3)Cl(H2L1–3)3]Cl3} (M = Re, 1–3; M = Tc, 4–6). The molecular structures of 1 and 3 were determined by X-ray diffraction. When the reactions were carried out with benzothiazole-2-thiol (HL4) and benzoxazole-2-thiol (HL5), neutral paramagnetic monosubstituted M(III) complexes [M(PPh3)2Cl2(L4,5)] (M = Re, 8, 9; M = Tc, 10, 11) were obtained. In these compounds, the central metal ions adopt an octahedral coordination geometry as authenticated by single crystal X-ray diffraction analysis of 8 and 11. Rhenium and technetium complexes 1, 4 and rhenium chelate compounds 8, 9 have been also synthesized by reduction of [MO4]− with PPh3 and HCl in the presence of the appropriate ligand. All the complexes were characterized by elemental analyses, FTIR and NMR spectroscopy.