Molecular Structure of 1,5-Diazabicyclo[3.1.0]hexane as Determined by Gas Electron Diffraction and Quantum-Chemical Calculations
Vishnevskiy, Yuri V.
Vishnevskiy
Yuri V.
Vogt, Natalja
Vogt
Natalja
Vogt, Jürgen
Vogt
Jürgen
Rykov, Anatolii N.
Rykov
Anatolii N.
Kuznetsov, Vladimir V.
Kuznetsov
Vladimir V.
Makhova, Nina N.
Makhova
Nina N.
Vilkov, Lev V.
Vilkov
Lev V.
The equilibrium molecular structure and conformation of 1,5-diazabicyclo[3.1.0]hexane (DABH) has been studied by the gas-phase electron-diffraction method at 20 °C and quantum-chemical calculations. Three possible conformations of DABH were considered: boat, chair, and twist. According to the experimental and theoretical results, DABH exists exclusively as a boat conformation of Cs symmetry at the temperature of the experiment. The MP2 calculations predict the stable chair and twist conformations to be 3.8 and 49.5 kcal mol−1 above the boat form, respectively. The most important semi-experimental geometrical parameters of DABH (re, Å and ∠e, deg) are (N1−N5) = 1.506(13), (N1−C6) = 1.442(2), (N1−C2) = 1.469(4), (C2−C3) = 1.524(7), (C6−N1−C2) = 114.8(8), (N5−N1−C2) = 107.7(4), (N1−C2−C3) = 106.5(9), and (C2−C3−C4) = 104.0(10). The natural bond orbital (NBO) analysis has shown that the most important stabilization factor in the boat conformation is the n(N) → σ*(C−C) anomeric effect. The geometry calculations and NBO analysis have been performed also for the bicyclohexane molecule.
112
23
5243-5250
5243-5250
American Chemical Society (ACS)
2008
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