- Reactions of laser-ablated beryllium atoms with hydrogen cyanide in excess argon. FTIR spectra and quantum chemical calculations on BeCN, BeCN, HBeCN, and HBeNC
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Laser-ablated beryllium atoms have been reacted with hydrogen cyanide (H12CN, H13CN, and D12CN) during condensation in excess argon at 6-7 K. In the matrix infrared spectrum, the major products observed are BeNC, BeCN, HBeNC, and HBeCN. Consistent with typical beryllium bonding, these new beryllium species are linear molecules. Density functional theory calculations on these products with the BP86 functional and 6-31 1G* basis sets predict vibrational frequencies extremely well, even for HBeCN where mixing between the nearly isoenergetic Be-H and C≡N stretching modes causes significant complications in the spectra. Although B3LYP and MP2 calculations are more sophisticated than the BP86 method, they do not predict the vibrational frequencies of these products nearly as well. More important is the carbon 12/13 isotopic frequency ratio as a description of the normal modes, and the BP86 method generates 12/13 ratios much closer to observed values for HBeCN than frequency ratios from the more time-consuming CISD method.
- Lanzisera, Dominick V.,Andrews, Lester
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p. 6392 - 6398
(2007/10/03)
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- Reactions of beryllium atoms with hydrogen. Matrix infrared spectra of novel product molecules
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Beryllium atoms formed by pulsed laser ablation have been codeposited with gaseous mixtures of hydrogen diluted in argon (concentrations varied from 25:1 to 100:1) onto a substrate at 10 K. Infrared spectroscopy on the reaction mixture identified six novel product molecules - BeH, BeH2, BeBeH, HBeBeH, HBeHBeH, and HBe(H)2-BeH. Assignments of infrared absorption bands were made on the basis of broad-band photolysis and annealing behavior, isotopic substitutions, and ab initio calculations performed at the MBPT(2) level. The major products initially are BeH (1970.0 cm-1) and the previously unobserved BeH2 molecule (v3 = 2159.1 cm-1, v2 = 697.9 cm-1) with formation of the three dimers HBeBeH, HBeHBeH, and HBe(H)2BeH at the expense of the initial reaction products upon annealing of the matrix to 30 K. The former dimer involves a stable Be-Be bond, and the latter dimers incorporate bridging hydrogen atoms. The new Be2H molecule (2013.7, 540.0 cm-1) is a minor product in these experiments, which exhibits a stronger Be-Be bond than Be2.
- Tague Jr., Thomas J.,Andrews, Lester
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p. 12111 - 12116
(2007/10/02)
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