Publication
Title
On the weakly $C-H\cdots\pi$ hydrogen bonded complexes of sevoflurane and benzene
Author
Abstract
 A vibrational assignment of the anaesthetic sevoflurane, (CF3)2CHOCH2F, is proposed and its interaction with the aromatic model compound benzene is studied using vibrational spectroscopy of supersonic jet expansions and of cryosolutions in liquid xenon. Ab initio calculations, at the MP2/cc-pVDZ and MP2/aug-cc-pVDZ levels, predict two isomers for the 1 : 1 complex, one in which the near-cis, gauche conformer of sevoflurane is hydrogen bonded through its isopropyl-hydrogen atom, the other in which the same conformer is bonded through a bifurcated hydrogen bond with the fluoromethyl hydrogen atoms. From the experiments it is shown that the two isomers are formed, however with a strong population dominance of the isopropyl-bonded species, both in the jet and liquid phase spectra. The experimental complexation enthalpy in liquid xenon, ΔHo(LXe), of this species equals −10.9(2) kJ mol−1, as derived from the temperature dependent behaviour of the cryosolution spectra. Theoretical complexation enthalpies in liquid xenon were obtained by combining the complete basis set extrapolated complexation energies at the MP2/aug-cc-pVXZ (X = D,T) level with corrections derived from statistical thermodynamics and Monte Carlo Free Energy Perturbation calculations, resulting in a complexation enthalpy of −11.2(3) kJ mol−1 for the isopropyl-bonded complex, in very good agreement with the experimental value, and of −11.4(4) kJ mol−1, for the fluoromethyl-bonded complex. The Monte Carlo calculations show that the solvation entropy of the isopropyl-bonded species is considerably higher than that of the fluoromethyl-bonded complex, which assists in explaining its dominance in the liquid phase spectra.
Language
English
Source (journal)
Physical chemistry, chemical physics / Royal Society of Chemistry [London] - Cambridge, 1999, currens
Publication
Cambridge : 2011
ISSN
1463-9076 [print]
1463-9084 [online]
Volume/pages
13:31(2011), p. 14142-14152
ISI
000293172300029
Full text (Publisher's DOI)
Full text (publisher's version - intranet only)
UAntwerpen
 Faculty/Department Research group [E?say:metaLocaldata.cgzprojectinf] Publication type Subject Affiliation Publications with a UAntwerp address