ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Completely theoretical calculations for the structure, anharmonic force field up to partial sixth order, and vibrational frequencies of C3H+3, C3H2D+, C3HD+2, and C3D+3 have been carried out. The procedure included ab initio calculation of the vibrational energy surface at the 6-311 G4* + local MP4(SDQ) level and anharmonic vibrational configuration-interaction (CI) calculation using a variational expansion in a large, well-selected harmonic oscillator basis. The geometric parameters of C3H+3 are optimized as 1.3632 A(ring) for the C–C bond length and 1.0795 A(ring) for the C–H bond length. The fundamental vibrational frequencies of C3H+3 are 3193.5, 1622.1, 1015.5, 3148.8, 1297.5, 916.2, 756.8, and 1002.7 cm−1; those of C3H2D+, (3190.6, 3144.8), 2405.3, 1580.3, 1274.7, 913.4, 1001.2, 3146.3, 1295.2, 995.4, 717.8, 916.7 and 663.6 cm−1; those of C3HD+2, are 3164.7, 2434.0 (1541.6, 1506.8), 1276.0, 672.1, 824.3, 2361.6, 1261.3, 966.7, 762.3, 960.3, and 603.9 cm−1; and those of C3D+3 are (2536.7, 2451.8), 1487.4, 837.5, 2358.1, 1256.9, 671.9, 562.6, and 823.5 cm−1. The frequencies enclosed in parentheses are for Fermi resonance pairs, the prediction of which is handled automatically by this procedure. The theoretical vibrational frequencies agree with the experimental data available from both Raman and infrared spectra with 0.5% relative mean deviation. This agreement is as good as the experimental data allow, since the experiments were carried out in condensed phases and in the presence of counterions. The first overtone vibrational frequencies of C3H+3 are also predicted. The general applicability and present limitations of the method are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.456643
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