Conformation and Structure of Dichlorophosphoryl Isocyanate in the Gaseous and Solid Phases.

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 Cs 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 Cs symmetry with an O–P–N–C dihedral angle of 38.1(1)° due to intermolecular C···O contacts [2.881(4) Å]. 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). [ABSTRACT FROM AUTHOR]