Synthesis, Structure, and Spectroscopic Study of Redox-Active Heterometallic Cluster-Based Complexes [Re5MoSe8(CN)6]n

The heterometallic cluster-based compound K-5[Re5MoSe8(CN)(6)] was obtained by high-temperature reaction from a mixture of ReSe2 and MoSe2 in molten potassium cyanide. The redox behavior of the [Re5MoSe8(CN)(6)](5-) cluster anion was studied by cyclic voltammetry in aqueous and organic media showing two reversible one- electron-redox transitions with E-1/2 of -0.462 and 0.357 V versus Ag/AgCl in CH3CN. Aqueous media potentials were found to be noticeably shifted to higher values because of solvation. Chemically accessible potentials allowed us to structurally isolate and characterize the [Re5MoSe8(CN)(6)]n (n = 3-, 4-, and 5-) cluster complex in several charge states with corresponding cluster skeletal electron (CSE) numbers ranging from 24 to 22. The electronic absorption of the [Re5MoSe8(CN)(6)](n) cluster complex varies significantly upon a change of the CSE number, especially in the visible and near-IR regions. The local cluster core distortion upon electron removal was confirmed by density functional theory calculation, while the overall geometry of the cluster anion remained practically unaltered.

Automated summary

The heterometallic cluster-based compound K-5[Re5MoSe8(CN)(6)] was synthesized by high-temperature reaction, showing two reversible one-electron redox transitions in different media. By using cyclic voltammetry and density functional theory calculation, it was found that the electronic absorption and local cluster core distortion vary significantly with the change of the cluster skeletal electron (CSE) number, while the overall geometry of the cluster anion remains practically unaltered.