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Thermochemical stabilities and vibrational spectra of isomers of the chlorine oxide dimer
Author(s) -
McGrath M. P.,
Clemitshaw K. C.,
Rowland F. S.,
Hehre W. J.
Publication year - 1988
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl015i008p00883
Subject(s) - dimer , infrared , infrared spectroscopy , chemistry , spectral line , ab initio , potential energy surface , antisymmetric relation , ab initio quantum chemistry methods , molecular orbital , potential energy , computational chemistry , atomic physics , molecule , physics , optics , organic chemistry , astronomy , mathematical physics
Ab initio molecular orbital calculations have been carried out to determine the relative thermochemical stabilities and infrared vibrational spectra of isomers of the ClO . dimer. Two straight‐chain isomers, ClOOCl and ClOClO, and one branched species, ClClO 2 , have been identified as energy minima on the Cl 2 O 2 potential surface. The highest level calculations show ClOOCl and ClClO 2 to be of comparable stability, with ClOClO some 11 kcal mol −1 higher in energy. Intense infrared absorptions for ClOOCl are calculated at 765, 679 and 633 cm −1 . These correlate closely with two broad bands (centered at 740 and 653 cm −1 ) observed by Molina and Molina (1987) to result from the gas‐phase reactions of chlorine atoms with various ClO . precursors. The previous assignment of the 653 cm −1 band to ClOClO [Molina and Molina, 1987] is inconsistent with its calculated infrared spectrum. The calculations also suggest that the two most intense bands in the experimental infrared spectrum, at 1225 and 1057 cm −1 and previously assigned to ClOOCl, correspond instead to antisymmetric and symmetric stretching modes of ClO 2 functionality. These bands may indicate the presence of the third Cl 2 O 2 isomer, ClClO 2 , or an alternative species such as ClOClO 2 .