Hydrogen-Bonding Acceptor Character of Be, the Beryllium Three-Membered Ring.

The ability of Be as a hydrogen bond acceptor has been explored by studying the potential complexes between this molecule and a set of hydrogen bond donors (HF, HCl, HNC, HCN, HO, and HCCH). The electronic structure calculations for these complexes were carried out at the MP2 and CCSD(T) computational levels together with an extensive NBO, ELF, AIM, and electrostatic potential characterization of the isolated Be system. In all the complexes, the Be-Be σ bond acts as electron donor, with binding energies between 19 and 6 kJ mol. A comparison with the analogous cyclopropane:HX complexes shows similar binding energies and contributions of the DFT-SAPT energetic terms. A blue-shift of the harmonic frequencies of Be is observed upon complexation.