Synthesis, Structure, and Reactivity of a Tetranuclear Cerium(IV) Oxo Cluster Supported by the Kläui Tripodal Ligand [Co(η5‐C5H5){P(O)(OEt)2}3]−

A tetranuclear CeIV oxo cluster compound containing the Klaui tripodal ligand [Co(η5-C5H5){P(O)(OEt)2}3]− (LOEt−) has been synthesized and its reactions with H2O2, CO2, NO, and Bronsted acids have been studied. The treatment of [Ce(LOEt)(NO3)3] with Et4NOH in acetonitrile afforded the tetranuclear CeIV oxo cluster [Ce4(LOEt)4O7H2] (1) containing an adamantane-like {Ce4(μ2-O)6} core with a μ4-oxo ligand at the center. The reaction of 1 with H2O2 resulted in the formation of the peroxo cluster [Ce4(LOEt)4(μ4-O)(μ2-O2)4(μ2-OH)2] (2). The treatment of 1 with CO2 and NO led to isolation of [Ce(LOEt)2(CO3)] and [Ce(LOEt)(NO3)3], respectively. The protonation of 1 with HCl, ROH (R=2,4,6-trichlorophenyl), and Ph3SiOH yielded [Ce(LOEt)Cl3] (3), [Ce(LOEt)(OR)3] (4), and [Ce(LOEt)(OSiPh3)3] (5), respectively. The chloride ligands in 3 are labile and can be abstracted by silver(I) salts. The treatment of 3 with AgOTs (OTs−=tosylate) and Ag2O afforded [Ce(LOEt)(OTs)3] (6) and 1, respectively. The electrochemistry of the Ce-LOEt complexes has been studied by using cyclic voltammetry. The crystal structures of complexes 1–5 have been determined.