Olefin epoxidation by mono and bisperoxo complexes of Mo(VI): a density functional model study

Olefin epoxidation by Mo(VI) peroxo complexes was computationally investiga ted (DFT B3LYP) for various monoperoxo models X2MoO(O-2)(H2O)(NH3) with ani onic ligands X and for the experimentally known complex MoO(O-2) (dipic)(H2 O). All these monoperoxo complexes exhibit higher barriers for direct oxyge n transfer to ethylene than the reference bisperoxo complex MoO(O-2)(2)(H2O )(NH3) with the same base ligand configuration; the most electronegative li gands X induce the lowest barriers. A molecular orbital analysis reveals fa ctors that govern the activity of the peroxo ligand and corroborates the el ectrophilic character of the attack of a peroxo group on the olefin. (C) 20 00 Elsevier Science B.V. All rights reserved.