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

Reactivity of new tetrahedral rhenium cluster complexes with pnictogenide inner ligands μ 3 -As 3- , μ 3 -Sb 3- , and μ 3 -Bi 3- has been investigated in reactions with aqueous H 2 O 2 . It has been found that the oxidation of clusters [{Re 4 As 3 Q}(CN) 12 ] 7- (Q = S or Se) led to the formation of stable clusters with μ 3 -(AsO) 3- ligands. Under the same conditions, the oxidation of [{Re 4 As 2 S 2 }(CN) 12 ] 6- cluster led to substitution of μ 3 -As 3- ligands to μ 3 -O 2- . The resulting cluster [{Re 4 O 2 S 2 }(CN) 12 ] 4- easily undergoes further oxidation, and even at room temperature, a unique {Re 4 } to {Re 3 } rearrangement occurs with the formation of the new triangular cluster [{Re 3 (μ 3 -S)(μ-O) 2 (μ-SO 2 )}(CN) 9 ] 5- . Upon heating, this process proceeds faster and the triangular cluster can be isolated as individual compounds. Cluster anions [{Re 4 SbSe 3 }(CN) 12 ] 5- and [{Re 4 BiS 3 }(CN) 12 ] 5- reacted with H 2 O 2 , yielding clusters containing μ 3 -O 2- ligands, namely, [{Re 4 OSe 3 }(CN) 12 ] 4- and [{Re 4 OS 3 }(CN) 12 ] 4- . This indicates that oxidized forms of μ 3 -Sb 3- and μ 3 -Bi 3- ligands can be easily substituted.