Anomeric effect in N-azidomethylpyrrolidine: gas-phase electron diffraction and theoretical study.

Gas-phase electron-diffraction data and high-level quantum chemical calculations have been used to study the conformational behaviour of N-azidomethylpyrrolidine. The two most stable conformers with a relative abundance of about 80% at 298 K possess gauche orientation of the azidomethyl group around the C-N(pyr) bond (C-N(azido)gauche with respect to the endocyclic N(pyr)-C bond). This orientation is a strong manifestation of an anomeric effect.

Flexibility of the saturated five-membered ring in 2,5-pyrrolidinedione (succinimide): electron diffraction and quantum-chemical studies with use of vibrational spectroscopy data.

The flexibility of succinimide molecule has been studied for the first time by quantum-chemical (at the MP2 level with up to the 6-311G(3df,2p) basis sets) and gas-phase electron diffraction (GED) methods using vibrational spectroscopy data from literature. The analysis of vibrational spectra, performed for the molecular model of C(2v) symmetry (predicted by high-level ab initio calculations) using the scaling procedure, has shown that the two out-of-plane ring motions, that is, ring-bending and ring-twisting, are practically pure modes of different symmetry types and can be considered separately. The one-dimensional potential curves for the ring-bending and ring-twisting vibrations calculated at the MP2(full)/6-311G(3df,2p) level could be approximated by harmonic and anharmonic functions, respectively.

Molecular structure of 1,5-diazabicyclo[3.1.0]hexane as determined by gas electron diffraction and quantum-chemical calculations.

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 degrees C and quantum-chemical calculations.

Molecular structure, conformation, and potential to internal rotation of 2,6- and 3,5-difluoronitrobenzene studied by gas-phase electron diffraction and quantum chemical calculations.

3,5-Difluoronitrobenzene (3,5-DFNB) and 2,6-difluoronitrobenzene (2,6-DFNB) have been studied by gas-phase electron diffraction (GED), MP2 ab initio, and by B3LYP density functional calculations. Refinements of r h1 and r e static and r h1 dynamic GED models were carried out for both molecules. Equilibrium r e structures were determined using anharmonic vibrational corrections to the internuclear distances ( r e - r a) calculated from B3LYP/cc-pVTZ cubic force fields.

Molecular structure and conformational composition of 1,3-dihydroxyacetone studied by combined analysis of gas-phase electron diffraction data, rotational constants, and results of theoretical calculations. Ideal gas thermodynamic properties of 1,3-dihydroxyacetone.

The molecular structure of 1,3-dihydroxyacetone (DHA) has been studied by gas-phase electron diffraction (GED), combined analysis of GED and microwave (MW) data, ab initio, and density functional theory calculations. The equilibrium re structure of DHA was determined by a joint analysis of the GED data and rotational constants taken from the literature. The anharmonic vibrational corrections to the internuclear distances (re-ra) and to the rotational constants (B(i)e-B(i)0) needed for the estimation of the re structure were calculated from the B3LYP/cc-pVTZ cubic force field.