Frontier molecular orbital analysis of Cu – O reactivity n 2 *

Frontier molecular orbital (FMO) theory coupled with density functional calculations has been applied to investigate the chemical 2 2 22 reactivity of three key bioinorganic Cu –O complexes, the mononuclear end-on hydroperoxo-Cu(II), the side-on bridged m–h :h –O n 2 2 Cu(II) dimer and the bis-m-oxo Cu(III) dimer. Two acceptor orbitals (s* and p*) of each complex and two types of donating substrates 2 2 (s-substrate, phosphine; p-substrate, alkylbenzene) are considered in the electrophilic attack mechanism. The angular dependences of different reaction pathways are determined using FMO theory and the angular overlap model. Including steric effects, the s*/s and p*/p pathways are found more reactive than the corresponding cross s*/p and p*/s pathways which have poor donor–acceptor orbital overlaps in the sterically constrained substrate access region.  2002 Elsevier Science Inc. All rights reserved.