Structures of [(CO2)n(CH3OH)m]− (n = 1−4, m = 1, 2) Cluster Anions
JPhysChemA_2008_112_4906.pdf 814 KB
Infrared photodissociation spectroscopy
ab initio calculation
The infrared photodissociation spectra of [(CO2)n(CH3OH)m]- (n = 1－4, m = 1, 2) are measured in the 2700－3700 cm-1 range. The observed spectra consist of an intense broad band characteristic of hydrogen-bonded OH stretching vibrations at ≈3300 cm-1 and congested vibrational bands around 2900 cm-1. No photofragment signal is observed for [(CO2)1, 2(CH3OH)1]- in the spectral range studied. Ab initio calculations are performed at the MP2/6-311++G** level to obtain structural information such as optimized structures, stabilization energies, and vibrational frequencies of [(CO2)n(CH3OH)m]-. Comparison between the experimental and theoretical results reveals the structural properties of [(CO2)n(CH3OH)m]-: (1) the incorporated CH3OH interacts directly with either CO2- or C2O4- core by forming an O－H・・・O linkage; (2) the introduction of CH3OH promotes charge localization in the clusters via the hydrogen-bond formation, resulting in the predominance of CO2-・(CH3OH)m(CO2)n-1 isomeric forms over C2O4-・(CH3OH)m(CO2)n-2; (iii) the hydroxyl group of CH3OH provides an additional solvation cite for neutral CO2 molecules.
This is a preprint of an article published by American Chemical Society in Journal of Physical Chemistry A, 2008, available online: http://pubs.acs.org/doi/abs/10.1021/jp800289g.
This work was supported by Grants-in-Aid for Scientific Research (Grant Nos. 18550007 and 19029011) from Japan Society for the Promotion of Science (JSPS), and from the Ministry of Education, Culture, Sports, Science and Technology (MEXT).
Journal of Physical Chemistry A
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American Chemical Society
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Graduate School of Science
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