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

摘要

Neutral oxorhenium(V) complexes with tridentate SNO Schiff bases have been prepared by substitution reactions on the square pyramidal ionic complex [Nbu_4][Re~VOCl_4] and on the six-coordinate rhenium precursor [Re~VOCl_3(PPh_3)_2]. The chlororhenium intermediate species [Re~VOCl(Ph-SNO-CH_3)] 1 allows the formation of the homologous iodo complex [Re~VOI(Ph-SNO-CH_3)] 2 by a halogen exchange reaction with lithium iodide. The similar complexes [Re~VOCl(Ph-SNO-H)] 3 and [Re~OCl(Naph-SNO-H)] 4 have been synthesized suing S-methyl-#beta#-N-(2-hydroxy-phenylmethylidene)dithiocarbazate (Naph-SNO-H). The ionic complex [Nbu_4][ReOCl_4] reacts with 4 equivalents of PPh_3 and Ph-SNO-H or Naph-SNO-H to give rise to the complexes [Re~OCl(Ph-SNO-H)(PPh_3)] 5 and [Re~VOCl(Naph-SNO-H)(PPh_3)] 7 which are smoothly converted in ethanolic solution into [Re~OCl(Ph-SNO-H)(PPh_3)] 6 and [Re~VOCl(Naph-SNO-H)(PPh_3)] 8, respectively. Each compound was characterized by elemental analysis, IR, NMR spectra and FAB mass spectrometry. The crystallographic structures of [ReOI(Ph-SNO-CH_3)] 2, [ReOCl(Ph-SNO-H)(PPh_3)] 5 and [ReOCl(Ph-SNO-H)(OPPh_3)] 6 were determined by single crystal X-ray diffraction method.