Redox-Dependent Intersite Coupling in Fe/Co/Se Clusters

Abstract

Intersite electronic coupling underpins cooperative behavior in biological systems and heterogeneous catalysts, yet how such coupling emerges and evolves with oxidation state remains poorly understood. Here, we use atomically precise Fe3Co6Se8L′6 (L′ = PPh2N(−)Tol) clusters to establish a direct connection between redox chemistry and intersite electronic communication within a well-defined metal–chalcogenide framework. Inner-sphere trioxidation of the cluster enables redistribution of charge across the Fe edge sites and the Co6Se8 support, as evidenced by single-crystal X-ray diffraction analysis, 57Fe Mössbauer spectroscopy, and magnetic and electrochemical measurements. The oxidized clusters exhibit a low-energy near-IR charge-transfer band and an overall antiferromagnetic response, while density functional theory reveals Fe/Se/Co orbital mixing and spin density distributed throughout the Fe–Se–Co framework. Together, these results identify a redox-dependent, support-mediated coupling regime in which the Co6Se8 scaffold electronically links spatially separated Fe sites.