Selective Oxidation of Inner Pnictogenide Ligands in Mixed-Ligand Rhenium Cubane-Type Cluster Complexes

Abstract

Reactivity of new tetrahedral rhenium cluster complexes with pnictogenide inner ligands μ3-As3–, μ3-Sb3–, and μ3-Bi3– has been investigated in reactions with aqueous H2O2. It has been found that the oxidation of clusters [{Re4As3Q}(CN)12]7– (Q = S or Se) led to the formation of stable clusters with μ3-(AsO)3– ligands. Under the same conditions, the oxidation of [{Re4As2S2}(CN)12]6– cluster led to substitution of μ3-As3– ligands to μ3-O2–. The resulting cluster [{Re4O2S2}(CN)12]4– easily undergoes further oxidation, and even at room temperature, a unique {Re4} to {Re3} rearrangement occurs with the formation of the new triangular cluster [{Re3(μ3-S)(μ-O)2(μ-SO2)}(CN)9]5–. Upon heating, this process proceeds faster and the triangular cluster can be isolated as individual compounds. Cluster anions [{Re4SbSe3}(CN)12]5– and [{Re4BiS3}(CN)12]5– reacted with H2O2, yielding clusters containing μ3-O2– ligands, namely, [{Re4OSe3}(CN)12]4– and [{Re4OS3}(CN)12]4–. This indicates that oxidized forms of μ3-Sb3– and μ3-Bi3– ligands can be easily substituted.