The luminescent [Mo6X8(NCS)6]2− (X = Cl, Br, I) clusters?: A computational study based on time-dependent density functional theory including spin–orbit and solvent-polarity effects

Relativistic time-dependent density functional (TDDFT) calculations including spin–orbit interactions via the zero order regular approximation (ZORA) and solvent effects were carried out on the [Mo6X8(NCS)6]2− cluster. These calculations indicate that the lowest energy electronic transitions of the LMCT type are similar to those observed in the strongly luminescent 24 electron hexanuclear rhenium chalcogenide clusters. The absorption maximum in all the solvents tends to shift to longer wavelengths as the face-capping halide ligand becomes heavier. Thus our calculations predict that the [Mo6X8(NCS)6]2− clusters could be luminescent showing an intensity dependence with respect to both, the nature of the face-capping ligand and the solvent polarity.