Properties of WAu12

Abstract

The icosahedral cluster-compound WAu₁₂ was recently predicted by Pyykkö and Runeberg and experimentally prepared in the gas phase by the group of Lai-Sheng Wang. The photoelectron spectra and electron affinity were reported; the other physical properties remain unknown. Anticipating further experimental studies on it, we report here predicted vibrational spectra, NMR chemical shifts, spin–spin coupling constants and quadrupole coupling constants as well as optical spectra at the level of single and double excitations. The population analysis is non-trivial. By direct numerical integration, a charge of roughly +1 is obtained for the central tungsten atom. The charge distribution is strongly delocalised but bonding regions are clearly seen. A considerable electric field gradient exists at the gold nuclei. Although the radial bonds are strong, the system is quite elastic. The DFT activation energy for rotating one hemisphere against the other one, at a D_5h transition state, is only about 20 kJ mol⁻¹. The corresponding h_u vibrational frequency is predicted to be slightly below 30 cm⁻¹.