VANADIUM(V) PEROXO COMPLEXES. NEW VERSATILE BIOMIMETIC REAGENTS FOR EXPOXIDATION OF OLEFINS AND HYDROXYLATION OF ALKANES AND AROMATIC HYDROCARBONS.

Article abstract of DOI:10.1021/ja00348a025

Novel covalent vandium(V) oxo peroxo complexes of general formula VO(O//2)(O-N)LL prime and anionic complexes with the general formula left bracket VO(O//2)(Pic)//2 right bracket ** minus A** plus L were synthesized and characterized by physicochemical methods and X-ray crystallography. The crystal structure of VO(O//2)(Pic) multiplied by (times) 2H//2O (Ia) revealed a pentagonal-bipyramidal environment, with a significant hydrogen bonding between the peroxo moiety and the equatorial water molecule. Protonated type II complexes (A** plus equals H** plus ) are dissociated in an aqueous solution and have an acidic nature (pK//a equals 1. 8) but are undissociated in a nonprotic solution, with a presumably peracid-like oxohydroperoxo structure. It is shown that vanadium peroxo complexes are effective oxidants in nonprotic solvents under mild conditions. They transform olefins to epoxides and cleavage products in a nonsteoroselective fashion (cis-2-butene gave a mixture of cis and trans epoxides). More interestingly, they hydroxylate aromatic hydrocarbons to phenols and alkanes to alcohols and ketones.