WHY DO NOT 7-CO-ORDINATED DIPEROXO MOLYBDENUM COMPLEXES OXIDIZE ALKENES - A THEORETICAL-ANALYSIS

The epoxidations of alkenes by 6- and 7-co-ordinated neutral diperoxo molybdenum complexes, and those by organic hydroperoxides and peracids were studied on the basis of quantum-chemical calculations. The 6-co- ordinated diperoxo molybdenum complex was found to have similar electr ophilic properties to that of the peracid, and the 7-co-ordinated comp lex showed electrophilic properties similar to those of the alkyl hydr operoxide. It was concluded that the 7-coordinated complex was less el ectrophilic because of additional electron donation to the central ion , destabilizing the anion-radical, which is reflected in their lower r eactivity towards the oxidation of olefins than the 6-co-ordinated one s.