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Ab initio calculations of the structural, energetic, and vibrational properties of some hydrogen bonded and van der Waals dimers. Part 4. The acetonitrile dimer
Author(s) -
Ford Thomas A.,
Glasser Leslie
Publication year - 2001
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.1325
Subject(s) - chemistry , counterpoise , ab initio , dimer , van der waals force , basis set , computational chemistry , ab initio quantum chemistry methods , perturbation theory (quantum mechanics) , trimer , hydrogen bond , acetonitrile , molecular physics , molecule , density functional theory , physics , quantum mechanics , organic chemistry , chromatography
The structures, interaction energies, Mulliken atomic charges, and vibrational spectra of five dimers of acetonitrile, CH 3 CN, have been determined by means of ab initio molecular orbital theory, at the second order level of Møller–Plesset perturbation theory, using the 6‐31++G(d,p) split‐valence polarized basis set, augmented with diffuse functions. The structural features of the dimers are discussed, as well as their respective interaction energies, which have been corrected for basis set superposition error by the full counterpoise technique of Boys and Bernardi. The atomic charge reorganizations resulting from dimerization have also been discussed. The vibrational wavenumbers and infrared intensities of each dimer have been computed and, in the case of the most probable dimer, they have been used to determine the wavenumber shifts relative to the corresponding modes of the monomer. The shifts have been compared with those in the infrared and Raman spectra of acetonitrile molecules trapped in cryogenic matrices, previously reported in the literature. The computed and experimental results support the conclusion that the favored dimer structure is a centrosymmetric cyclic species of C 2h symmetry, stabilized by two weak CHN hydrogen bonds. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 226–240, 2001