title: New diagnostic of the most populated conformer of tetrahydrofuran in the gas phase.
abstract: The most populated conformer of tetrahydrofuran (C(4)H(8)O) has been diagnosed as the Cs conformer in the present study, jointly using experimental electron momentum spectroscopy (EMS) and quantum mechanics. Our B3LYP/6-311++G** model indicates that the C1 conformation, which is one of the three possible conformations of tetrahydrofuran produced by pseudorotation in the gas phase, is a transition state due to its imaginary frequencies, in agreement with the prediction from a recent ab initio MP2/aug-cc-pVTZ study (J. Chem. Phys. 2005, 122, 204303). The study has identified the fingerprint of the highest occupied molecular orbital (HOMO) of the C(s) (12a') conformer as the most populated conformer. The identification of the C(s) structure, therefore, leads to the orbital-based assignment of the ionization binding energy spectra of tetrahydrofuran for the first time, on the basis of the outer valence Green function OVGF/6-31G* model and the density functional theory (DFT) SAOP/ET-PVQZ model. The present study explores an innovative approach to study molecular stabilities. It also indicates that energetic properties are not always the most appropriate means to study conformer-rich biological systems.
authors.affiliation: Department of Physics and Key Laboratory of Atomic and Molecular NanoSciences of MOE, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Tiecheng
authors.initials: T
authors.lastname: Yang
authors.forename: Guolin
authors.initials: G
authors.lastname: Su
authors.forename: Chuangang
authors.initials: C
authors.lastname: Ning
authors.forename: Jingkang
authors.initials: J
authors.lastname: Deng
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Shufeng
authors.initials: S
authors.lastname: Zhang
authors.forename: Xueguang
authors.initials: X
authors.lastname: Ren
authors.forename: Yanru
authors.initials: Y
authors.lastname: Huang
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003198:Computer Simulation; D004355:Drug Stability; D004583:Electrons; D005663:Furans / Q000737:chemistry*; D008968:Molecular Conformation; D015394:Molecular Structure; D012996:Solutions; D013053:Spectrophotometry; D013057:Spectrum Analysis; D013816:Thermodynamics
chemical_list: D005663:Furans; D012996:Solutions; C018674:tetrahydrofuran