Formations of a nonanuclear peroxo molybdate and its heptanuclear precursor

Coupling reaction of peroxo heptanuclear and dinuclear molybdenum complexes K6[Mo7O22(O2)2]·9H2O (1) and K2[Mo2O3(O2)4(H2O)2]·2H2O (2) results in the formation of a nonanuclear peroxo molybdate K8[Mo9O25(O2)6]·9H2O (3) in a weak acidic solution, which is promoted by the existence of lactic acid. The activation of peroxo group in compound 3 shows obvious O–O bond activation in comparison with 1, which is based on structural data and infra-red analyses.