Synthesis, properties and spectroscopic studies of rhenium(v) complexes stabilized by tridentate Schiff bases derived from S-methyl dithiocarbazate

Neutral oxorhenium(V) complexes with tridentate SNO Schiff bases have been prepared by substitution reactions on the square pyramidal ionic complex [NBu4][(ReOCl4)-O-V] and on the six-coordinate rhenium precursor [(ReOCl3)-O-V(PPh3)(2)]. The chlororhenium intermediate species [(ReOCl)-O-V(Ph-SNO-CH3)] 1 allows the formation of the homologous iodo complex [(ReOI)-O-V(Ph-SNO-CH3)] 2 by a halogen exchange reaction with lithium iodide. The similar complexes [ReVOCl(Ph-SNO-H)] 3 and [(ReOCl)-O-V(Naph-SNO-H)] 4 have been synthesised using S-methyl-beta -N-(2-hydroxyphenylmethylidene)dithiocarbazate (Ph-SNO-H) and S-methyl-beta -N-(2-hydroxynaphthylmethylidene)dithiocarbazate (Naph-SNO-H). The ionic complex [NBu4][ReOCl4] reacts with 4 equivalents of PPh3 and Ph-SNO-H or Naph-SNO-H to give rise to the complexes [(ReOCl)-O-V(Ph-SNO-H)(PPh3)] 5 and [(ReOCl)-O-V( Naph-SNO-H)-(PPh3)] 7 which are smoothly converted in ethanolic solution into [(ReOCl)-O-V(Ph-SNO-H)(OPPh3)] 6 and [(ReOCl)-O-V(Naph-SNO-H)(OPPh3)] 8, respectively. Each compound was characterised by elemental analysis, IR, NMR spectra and FAB mass spectrometry. The crystallographic structures of [ReOI(Ph-SNO-CH3)] 2, [ReOCl(Ph-SNO-H)(PPh3)] 5 and [ReOCl(Ph-SNO-H)(OPPh3)] 6 were determined by single crystal X-ray diffraction methods.