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Ab initio molecular orbital study on the structures and energetics of CH 3 OH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n and CH 3 SH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n in the gas phase
Author(s) -
Masamura Masao
Publication year - 2000
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/1096-987x(20010115)22:1<125::aid-jcc12>3.0.co;2-0
Subject(s) - chemistry , ab initio , bond length , gas phase , physics , crystallography , crystal structure , organic chemistry
The purpose of this study was to calculate the structures and energetics of CH 3 OH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n and CH 3 SH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n in the gas phase: we asked how the CH 3 OH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} and CH 3 SH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} moieties of CH 3 OH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n and CH 3 SH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n change with an increase in n and how can we reproduce the experimental values Δ H ° n −1, n . For this purpose, we carried out full geometry optimizations with MP2/6‐31+G(d,p) for CH 3 OH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n ( n =0,1,2,3,4,5) and CH 3 SH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n ( n =0,1,2,3,4). We also performed a vibrational analysis for all clusters in the optimized structures to confirm that all vibrational frequencies are real. All of the vibrational frequencies of these clusters are real, and they correspond to equilibrium structures. For CH 3 OH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n , when n increases, (1) the CO bond length decreases, (2) the CH bond lengths do not change, (3) the OH bond lengths increase, (4) the OCH bond angles increase, (5) the COH bond angles decrease, (6) the charge on CH 3 becomes less positive, and (7) these predicted values, except for the OH bond lengths of CH 3 OH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n , approach the corresponding values in CH 3 OH. The CO bond length in CH 3 OH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) 5 is shorter than that in CH 3 OH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} in the gas phase by 0.061 Å at the MP2/6‐31+G(d,p) level. Except for the SH bond lengths in CH 3 SH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} (H 2 O) n , however, the structure of the CH 3 SH \documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document} moiety does not change with an increase in n . © 2000 John Wiley & Sons, Inc. J Comput Chem 22: 125–131, 2001