title: Conformational and Bonding Properties of 3,3-Dimethyl- and 6,6-Dimethyl-1,5-diazabicyclo[3.1.0]hexane: A Case Study Employing the Monte Carlo Method in Gas Electron Diffraction.
abstract: Gas-phase structures of two isomers of dimethyl-substituted 1,5-diazabicyclo[3.1.0]hexanes, namely, 3,3-dimethyl- and 6,6-dimethyl-1,5-diazabicyclo[3.1.0]hexane molecules, have been determined by gas electron diffraction method. A new approach based on the Monte Carlo method has been developed and used for the analysis of precision and accuracy of the refined structures. It was found that at 57 °C 3,3-dimethyl derivative exists as a mixture of chair and boat conformers with abundances 68(8)% and 32(8)%, respectively. 6,6-Dimethyl-1,5-diazabicyclo[3.1.0]hexane at 50 °C has only one stable conformation with planar 5-ring within error limits. Theoretical calculations predict that the 6,6-dimethyl isomer is more stable in comparison to the 3,3-dimethyl isomer with energy difference 3-5 kcal mol(-1). In order to explain the relative stability and bonding properties of different structures the natural bond orbitals (NBO), atoms in molecules (AIM), and interacting quantum atoms (IQA) analyses were performed.
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Universität Bielefeld , Universitätsstrasse 25, 33615, Bielefeld, Germany.
authors.forename: Yury V
authors.initials: YV
authors.lastname: Vishnevskiy
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Universität Bielefeld , Universitätsstrasse 25, 33615, Bielefeld, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Schwabedissen
authors.affiliation: Department of Chemistry, M.V. Lomonosov Moscow State University , Vorob'evy gory 1, bld. 3, 119992 GSP-2 Moscow, Russian Federation.
authors.forename: Anatolii N
authors.initials: AN
authors.lastname: Rykov
authors.affiliation: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences , Leninsky prosp. 47, 119991 Moscow, Russian Federation.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Kuznetsov
authors.affiliation: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences , Leninsky prosp. 47, 119991 Moscow, Russian Federation.
authors.forename: Nina N
authors.initials: NN
authors.lastname: Makhova