THIO-LIGATION TO VANADIUM - THE NSSN AND S'N'O DONOR SETS (N EQUALS PYRIDINE, N' EQUALS ENAMINE, S EQUALS THIOETHER, S' EQUALS THIOLATE)

The tetradentate, neutral disulfide [bis(thioether)] ligand 1,6-bis(o- pyridyl)-2,4-dithiahexane, NSSN, reacts with [VCl2(tmeda)(2)] to form the octahedral (all-cis; C-2v-symmetric) complex [VCl2(NSSN)] 1, the f irst low-valent vanadium complex in which the thio functions are exclu sively organic sulfides. Treatment of [VOCl2(thf)(2)] with o-mercaptoa niline, followed by reaction with o-hydroxynaphthaldehyde yields the n on-oxo V-IV complex [V(S'N'O)(2)] 2, derived from the Schiff base HS'N 'OH, where O and S' are phenolate and thiophenolate functions, respect ively, and N' is the Schiff base (enamine) nitrogen. Complex 2, with t he ligands in a distorted trigonal-antiprismatic array, is a rare exam ple of a structurally characterized complex where the Schiff base is p reserved at the expense of its thiazoline tautomeric form.