Ab initio study on cyanamide and isocyanamide

Spectroscopic parameters, namely force constants and dipole-moment derivatives of cyanamide and isocyanamide at their equilibrium geometry, are studied by the ab initio MO method. The configuration of the former of the two structural isomers has amide character, and the latter amine character. The assignments of skeletal-deformation vibrations are reinvestigated experimentally as well. This study supports Ogilvie's attribution of what he observed to the vibrational spectrum of isocyanamide and explains the anomalous infrared intensity in the spectrum. A special theoretical treatment of amino wagging motion is presented, which includes the inversion effect, and which enables the prediction of the inversion splitting of isocyanamide.