Carbenes and silylenes as hydrogen bond acceptors

A theoretical study of the capability of carbenes and silylenes as hydrogen bond (HE) accepters has been carried out. The complexes formed by singlet H2C:, H2Si:, and F2C:, as electron donors, and HF, HCN, H2O, NH3, and CH3+, as electron accepters, have been analyzed. The calculations have been carried out using the 6-31G** and 6-311++G** at the HF, MP2, and MP4 levels of theory. The topology of the electron density of the HE complexes has been characterized using the AIM methodology. The results show that carbenes are good electron donors as indicated by the large interaction energies and electron densities on the HE critical bonds.