Vanadium(IV and V) complexes containing SNO (dithiocarbonylhydrazone; thiosemicarbazone) donor sets

The VO2+ complexes [VOCl(ONS)] (3) and [VO(ONS)'] (4), and the VO3+ complex es [VO(OEt)(ONS)'] (5) {ONS = (R)-salicylaldehyde thiosemicarbazonate(1-) R = 5,6-C4H4 (3a) or 3-OMe (3b); (ONS)' = (R)-salicylaldehyde[benzylmercapto thiocarbonylhydrazonate(2-) ], R = H, (4a/5a) or 3-OMe (4b/5b)} have been p repared and characterised by IR, EPR, H-1-, and V-51-NMR spectroscopy. In ( S)-sBuOH, 4a converts to [VO{(S)-OsBu}(ONS) '] (5c) and [VO(OH)(ONS)'] (or a condensation product thereof), Solutions of 5c show three V-51 NMR signal s, two of which are due to two diastereomers. The EPR spectra of 3 and 4 in THF reveal the presence of octahedral species in solution. The crystal and molecular structures of complexes 3a.OCMe2, 5a, and 5b have been obtained, revealing basically a tetragonal pyramid, and coordination of the sulfur f unction in the thiocarbonyl (3) or enethiolate mode (5). The relevance of t he compounds to bioinorganic aspects is addressed.