Preparation and electron spin resonance spectra of some molybdenum(V) complexes of Schiff-base ligands and their oxidation to molybdenum(VI)

Abstract

Trichloro-oxomolybdenum(V) reacts with Schiff bases H₂L in the presence of base, with the dilithium salt Li₂L, or with the bis(trimethvlsilyl) derivative L(SiMe₃)₂[L = salen, salon, salphen, 3-MeO-salen, 3-MeO-salphen, 3-MeO-salpn, or 2,2′-bi(2,3-dihydrobenzothiazolyl)(H₂bzt)] to give the complexes [MoCl(O)L]. E.s.r., and i.r. spectral data suggest that the complex with L = salen[ethylenebis(salicylideneiminato)] exists as a mixture of cis and trans isomers, but with L = salpn [propane-1,3-diylbis(salicylideneiminato)] or salphen [o-phenylenebis-(salicylideneiminato)] solely in the trans and cis configurations, respectively. On heating under reflux in air, the [MoCl(O)L] complexes are oxidised to [MoO₂L].