REACTIONS OF LASER-ABLATED BERYLLIUM ATOMS WITH HYDROGEN-CYANIDE IN EXCESS ARGON - FTIR SPECTRA AND QUANTUM-CHEMICAL CALCULATIONS ON BECN, BENC, HBECN, AND HBENC

Laser-ablated beryllium atoms have been reacted with hydrogen cyanide ((HCN)-C-12, (HCN)-C-13, and (DCN)-C-12) during condensation in excess argon at 6-7 K. In the matrix infrared spectrum, the major products o bserved are BeNC, BeCN, HBeNC, and HBeCN. Consistent with typical bery llium bonding, these new beryllium species are linear molecules. Densi ty functional theory calculations on these products with the BP86 func tional and 6-311G basis sets predict vibrational frequencies extremel y well, even for HBeCN where mixing between the neatly isoenergetic Be -H and C=N stretching modes causes significant complications in the sp ectra. Although B3LYP and MP2 calculations are more sophisticated than the BP86 method, they do not predict the vibrational frequencies of t hese products nearly as well. More important is the carbon 12/13 isoto pic frequency ratio as a description of the normal modes, and the BP86 method generates 12/13 ratios much closer to observed values for HBeC N than frequency ratios from the more time-consuming CISD method.