PUB - Publikationen an der Universität Bielefeld

The conformational properties and the molecular structure of dichlorophosphoryl isocyanate, Cl2P(O)NCO, were studied by combining vibrational spectroscopy (IR and Raman), gas-phase electron diffraction (GED), X-ray crystallography (XRD), and quantum-chemical calculations. Computationally, two conformers of C-s symmetry with the P=O bond being in syn or anti configuration relative to the NCO group are predicted to be close in energy (ca. 2 kJ mol(-1)). Experimentally, both gas-phase and matrix-isolation IR spectra of Cl2P(O)NCO suggest the presence of a single conformer, which was determined to be the energetically more favorable syn-conformer. This was also found to exist in the solid state by low-temperature XRD. However, the molecule in the solid state is significantly distorted from ideal C-s symmetry with an O-P-N-C dihedral angle of 38.1(1)degrees due to intermolecular C center dot center dot center dot O contacts [2.881(4) angstrom]. In the gas phase, the GED analysis suggests that the molecule exists predominantly as syn-conformer but with dynamic behavior about the two minimum structures (syn and anti).