Calculated paramagnetic resonance parameters (g,Ahfi) of the Re6S8Br63−, Re6S8I63−, and Re6Se8I63− cluster ions

Abstract

Dirac molecular orbital calculations on the octahedral paramagnetic Re6S8Br63−, Re6S8I63−, and Re6Se8I63− 23e cluster ions, are reported. As the parent diamagnetic Re6Q8X64− (Q=S, Se, X=halide, etc.) 24e clusters, the calculated relativistic molecular orbitals indicate that the manifold of closely spaced unoccupied energy levels are mainly localized on the octahedral [Re6Q8]3+ core, while the cluster highest occupied molecular orbitals and the manifold below it are largely centered on the terminal halide ligands. These results suggest that the title 23e cluster ions could also be luminescent. The current calculations predict an isotropic Zeeman interaction for each cluster, which is in good agreement with the available data from electron paramagnetic resonance experiments. We also calculated the paramagnetic hyperfine interactions (Ahfi) of the Rre187, CL35, Br79, I127, S33, and Se77 nuclei, allowing us to describe that the metal and apical ligand magnetic hyperfine tensors are anisotropic, while the magnetic hyperfine tensors of the capping (S, Se) ligands are small and isotropic. These reversible redox (24e/23e) couples [Re6Q8X64−/Re6Q8X63−] could become part of molecular nanocells for applications in molecular electronics, and, also as part of nanosensor devices.