title: Applicability of the hindered rotor scheme to the puckering mode in four-membered rings.
abstract: The hindered rotor scheme, originally developed for internal rotors in flexible chains (Van Speybroeck, V.; Van Neck, D.; Waroquier, M.; Wauters, S.; Saeys, M.; Marin, G. B. J. Phys. Chem. A 2000, 104, 10939), is extended to puckering motions in four-membered rings. The applicability of the approach is tested in a variety of heterocyclic compounds for which the partition function, entropy, and heat capacity are calculated. The entropy may be substantially altered by a correct description of the puckering mode. The equilibrium puckering angle ranges between 0 degrees and 30 degrees depending on the heterosubstitution X (CH2, O, S, NH, PH, C=O, C=S, C=NH, C=PH) in the four-membered ring.
authors.affiliation: Center of Molecular Modeling, Laboratory of Theoretical Physics, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Vansteenkiste
authors.forename: Veronique
authors.initials: V
authors.lastname: Van Speybroeck
authors.forename: Guido
authors.initials: G
authors.lastname: Verniest
authors.forename: Norbert
authors.initials: N
authors.lastname: De Kimpe
authors.forename: Michel
authors.initials: M
authors.lastname: Waroquier
mesh_terms: D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry*; D008962:Models, Theoretical; D008968:Molecular Conformation; D015394:Molecular Structure; D013816:Thermodynamics
chemical_list: D006576:Heterocyclic Compounds, 4 or More Rings