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4216831 
Journal Article 
Multi-structural thermodynamics of C-H bond dissociation in hexane and isohexane yielding seven isomeric hexyl radicals 
Zheng, J; Yu, T; Truhlar, DG 
2011 
1 
Physical Chemistry Chemical Physics
ISSN: 1463-9076
EISSN: 1463-9084 
ROYAL SOC CHEMISTRY 
CAMBRIDGE 
13 
43 
19318-19324 
English 
21984114 
WOS:000296203500014 
The C-H bond dissociation processes of n-hexane and isohexane involve 23 and 13 conformational structures, respectively in the parent molecules and 14-45 conformational structures in each of the seven isomeric products that we studied. Here we use the recently developed multi-structural (MS) thermodynamics method and CCSD(T)-F12a/jul-cc-pVTZ//M06-2X/6-311+G(2df,2p) potential energy surfaces to calculate the enthalpy, entropy, and heat capacity of n-hexane, isohexane, and seven of the possible radical products of dissociation of C-H bonds. We compare our calculations with the limited experimental data and with values obtained by group additivity fits used to extend the experimental data. This work shows that using the MS method involving a full set of structural isomers with density functional geometries, scaled density functional frequencies, and coupled cluster single-point energies can predict thermodynamic functions of complex molecules and bond dissociation reactions with chemical accuracy. The method should be useful to obtain thermodynamic data for complex molecules for which such data has not been measured and to obtain thermodynamic data at temperatures outside the temperature range where measurements are available.