REACTIONS OF LASER-ABLATED BERYLLIUM ATOMS WITH HYDROGEN-CYANIDE IN EXCESS ARGON - FTIR SPECTRA AND QUANTUM-CHEMICAL CALCULATIONS ON BECN, BENC, HBECN, AND HBENC
Dv. Lanzisera et L. Andrews, REACTIONS OF LASER-ABLATED BERYLLIUM ATOMS WITH HYDROGEN-CYANIDE IN EXCESS ARGON - FTIR SPECTRA AND QUANTUM-CHEMICAL CALCULATIONS ON BECN, BENC, HBECN, AND HBENC, Journal of the American Chemical Society, 119(27), 1997, pp. 6392-6398
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.