Electronic structure and bonding of the [W6S8(CN)6]6− cluster anion

Dirac–Slater multiple scattering and its non-relativistic limit calculations on the reduced octahedral (20e) [W6S8(CN)6]6− cluster ion are reported. The non-relativistic limit calculations predict a paramagnetic cluster with a triplet ground state, while the relativistic calculations predict a diamagnetic cluster with a singlet ground state, which is in agreement with the single sharp signal seen in 13C NMR experiments in deoxygenated D2O at room temperature. We have also calculated the relativistic electronic structure of the oxidized 19e [W6S8(CN)6]5− cluster ion. The calculated relativistic local density of states at the Fermi level of the [W6S8(CN)6]6− cluster ion differs from those calculated for the 24e [Re6S8(CN)6]4− cluster ion. This may explain the different role played by the axial cyanide ligands in their cluster reactivities.