Transition metal substituted sandwich-type polyoxometalates with a strong metal–C (imidazole) bond as anticancer agents

Two novel sandwich-type polyoxometalates {Na0.7M5.3(H2O)2(imi)2(Himi)(SbW9O33)2}6- (M = NiII (1), CoII (2), imi = imidazole) containing a strong M-Cimi bond were synthesized by a tetragonal cluster [Na2Sb8W36O132(H2O)4]22- {Sb8W36} precursor. Compound 1 was highly cytotoxic against gastric cancer cells by arresting the cell cycle in the S-phase and inducing cell apoptosis.