title: Microwave spectrum and conformational composition of (azidomethyl)cyclopropane (C3H5CH2N3).
abstract: The microwave spectrum of (azidomethyl)cyclopropane, C3H5CH2N3, has been investigated in the 26-90 GHz spectral range at a temperature of about -30 °C. Five rotameric forms of this compound, whose spectra can be distinguished by microwave spectroscopy, may exist. The spectra of three of them denoted III, IV, and V were assigned. The ground vibrational state spectra of III and V were assigned, while the ground and six vibrationally excited states were assigned for IV. These three rotamers all have a synclinal orientation of the H-C-C-N chain of atoms, while the C-C-N-N link is either + or - synclinal or antiperiplanar. Conformer IV, having synclinal orientation of the two said dihedral angles, was found to have the lowest energy by relative intensity measurements. Rotamer V has an energy that is 1.6(6) kJ/mol higher than the energy of IV, while the energy of III is 2.1(6) kJ/mol higher than the energy of IV. Quantum chemical calculations were performed at the MP2/cc-pVTZ and CCSD/cc-pVTZ levels of theory. The rotational constants obtained in the CCSD calculations are in good agreement with the experimental rotational constants, while the MP2 centrifugal distortion constants are generally in poorer agreement with their experimental counterparts.
authors.affiliation: Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo , Blindern, NO-0315 Oslo, Norway.
authors.forename: Harald
authors.initials: H
authors.lastname: Møllendal
authors.forename: Svein
authors.initials: S
authors.lastname: Samdal
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Guillemin