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Intermolecular Interactions between Halothane and Dimethyl Ether: A Cryosolution Infrared and Ab Initio Study
Author(s) -
Michielsen Bart,
Herrebout Wouter A.,
van der Veken Benjamin J.
Publication year - 2007
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200700126
Subject(s) - intermolecular force , ab initio , infrared , ab initio quantum chemistry methods , infrared spectroscopy , computational chemistry , dimethyl ether , chemistry , ether , intermolecular interaction , halothane , organic chemistry , molecule , physics , catalysis , quantum mechanics
The complex of halothane (CHClBrCF 3 ) and dimethyl ether has been investigated experimentally in solutions of liquid krypton using infrared spectroscopy and theoretically using ab initio calculations at the MP2/6‐311++G(d,p) level. The formation of a 1:1 complex was experimentally detected. The most stable ab initio geometry found is the one in which the CH bond of halothane interacts with the oxygen atom of dimethyl ether. The complexes in which the chlorine or the bromine atom of halothane interacts with the oxygen atom of the ether were found to be local energy minima and were less stable by 14.5 and 9.3 kJ mol −1 , respectively, than the global minimum. The formation of a single complex species was observed in the infrared spectra; the standard complexation enthalpy of this complex was determined to be −12.3(8) kJ mol −1 . Analysis of the observed complexation shifts supports the identification of the complex as the hydrogen‐bonded species. The CH stretching vibration of halothane was found to show a redshift upon complexation of 19(2) cm −1 . The infrared intensity ratios ε complex / ε monomer for the fundamental and its first overtone were measured to be 6.5(1) and 0.31(1). The frequency shift was analyzed using Morokuma‐type analysis, and the infrared intensity ratios were rationalized using a model including the mechanical and electric anharmonicity of the CH stretching fundamental.