Probing the Structural and Electronic Properties of Dirhenium Halide Clusters: A Density Functional Theory Study

Dirhenium halide dianions received considerable attention in past decades due to the unusual metal–metal quadruple bond. The systematic structural evolution of dirhenium halide clusters has not been sufficiently studied and hence is not well-understood. In this work, we report an in-depth investigation on the structures and electronic properties of doubly charged dirhenium halide clusters Re(2)X(8)(2−) (X = F, Cl, Br, I). Our computational efforts rely on the well-tested unbiased CALYPSO (Crystal structure AnaLYsis by Particle Swarm Optimization) method combined with density functional theory calculations. We find that all ground-state Re(2)X(8)(2−) clusters have cube-like structures of D(4h) symmetry with two Re atoms encapsulated in halogen framework. The reasonable agreement between the simulated and experimental photoelectron spectrum of the Re(2)Cl(8)(2−) cluster supports strongly the reliability of our computational strategy. The chemical bonding analysis reveals that the δ bond is the pivotal factor for the ground-state Re(2)X(8)(2−) (X = F, Cl, Br, I) clusters to maintain D(4h) symmetric cube-like structures, and the enhanced stability of Re(2)Cl(8)(2−) is mainly attributed to the chemical bonding of 5d orbital of Re atoms and 3p orbital of Cl atoms.