Deactivation of methylrhenium trioxide-peroxide catalysts by diverse and competing pathways

Methylrhenium trioxide, (MTO), and hydrogenperoxide give catalytically active peroxorhenium complexes, CH3ReO2(eta2-O2), (A) and CH3Re(O)(eta2-O2)2(H2O), (B). The complex decomposes to methanol and perrhenate ions in the presence of hydrogen peroxide. The attack by hydroxide on A or by HO2 on MTO explains the pH dependence of the complex. B decomposes slowly to give O2 and CH3ReO3, which is stable only in acidic medium. Variable temperature 1H-NMR reveals a labile coordinated water molecule in B and an anhydride form of A.