A microwave spectroscopic and quantum chemical study of propa-1,2-dienyl selenocyanate (H2CCHSeCN) and cyclopropyl selenocyanate (C3H5SeCN)?

Physical Chemistry Chemical Physics Pub Date: 2008-06-02 DOI: 10.1039/B803562H

Abstract

The microwave spectra of propa-1,2-dienyl selenocyanate, H2C[double bond, length as m-dash]C[double bond, length as m-dash]CHSeC[triple bond, length as m-dash]N, and cyclopropyl selenocyanate, C3H5SeC[triple bond, length as m-dash]N, are reported. The spectra of the ground and two vibrationally excited states of the 80Se isotopologue and the spectrum of the ground state of the 78Se isotopologue were assigned for one rotameric form of H2C[double bond, length as m-dash]C[double bond, length as m-dash]CHSeC[triple bond, length as m-dash]N. This conformer is characterized by a C–C–Se–C dihedral angle of 129(5)° from synperiplanar (0°) and is shown to be the global minimum of H2C[double bond, length as m-dash]C[double bond, length as m-dash]CHSeC[triple bond, length as m-dash]N. The spectra of the ground and of three vibrationally excited states of the 80Se isotopologue, as well as of the ground state of the 78Se isotopologue of one rotamer of C3H5SeC[triple bond, length as m-dash]N were assigned. This conformer has a H–C–Se–C dihedral angle of 80(4)° from synperiplanar and is at least 3 kJ mol?1 more stable than any other form of the molecule. The microwave study has been augmented by quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) and MP2/6-311++G(3df,3pd) levels of theory.

Graphical abstract: A microwave spectroscopic and quantum chemical study of propa-1,2-dienyl selenocyanate (H2 [[double bond, length as m-dash]] C [[double bond, length as m-dash]] CHSeC [[triple bond, length as m-dash]] N) and cyclopropyl selenocyanate (C3H5SeC [[triple bond, length as m-dash]] N)
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