Mechanism of Al³⁺-Catalyzed Oxidations of Hydrocarbons: Dramatic Activation of H₂O₂ toward O−O Homolysis in Complex [Al(H₂O)₄(OOH)(H₂O₂)]²⁺ Explains the Formation of HO• Radicals

A radical mechanism of hydrocarbon oxidations with the environmentally friendly and cheap homogeneous nontransition metal system [Al(H(2)O)(6)](3+)/H(2)O(2)/MeCN-H(2)O was proposed for the first time on the basis of DFT calculations. A dramatic activation of H(2)O(2) toward homolysis in the key intermediate [Al(H(2)O)(4)(OOH)(H(2)O(2))](2+) due to the presence of the easily oxidizable OOH coligand provides, without a change of metal oxidation state, the generation of HO(•) radicals, which then oxidize hydrocarbons. Nonradical mechanisms of the olefin epoxidation with the same catalytic system were also investigated.