New catecholato oxorhenium(V) complexes

Abstract

The complexes [ReO(L)(PPh₃)₂X][H₂L = catechol (H₂cat), tetrachlorocatechol (H₂tccat) or tetrabromocatechol (H₂tbcat); X = Cl or I], [NBuⁿ₄][ReO(L′)(tccat)₂](L′= OPPh₃, MeOH or pyridine), [NBuⁿ₄][ReO(OPPh₃)(tbcat)₂] and [ReO(PPh₃)(L″)₂]I [HL″= tropolone (2-hydroxycyclohepta-2,4,6-trien-1-one) or maltol (3-hydroxy-2-methylpyran-4-one)] have been isolated and their infrared, Raman, ³¹P and ¹³C NMR spectra are reported. The X-ray crystal structures of [NBuⁿ₄][ReO(OPPh₃)(tccat)₂]1 and [NBuⁿ₄][ReO(MeOH)(tccat)₂]2 are presented. In both molecules the co-ordination geometry about Re is very similar, being distorted octahedral with the catecholato ligands folded away from a very strongly bonded oxo ligand [1.576(8)Å in 1 and 1.653(11)Å in 2] with weakly bound OPPh₃ and MeOH ligands in the trans positions.