Infra-red spectra of sulphamide and sulphamide-d4

The infra-red spectra of sulphamide and sulphamide-d₄ have been recorded for ordinary and polarized radiations. The vibrational assignment has been made by referring to the infra-red dichroism as well as to the isotopic effect. Normal co-ordinate analysis of sulphamide and sulphamide-d₄ as nine atomic molecules has been carried out by assuming the molecular symmetry of C_2ν. The calculation of potential energy distributions has shown that the shift of the NSN symmetric and antisymmetric stretching bands on N-deuteration is attributed to the vibrational coupling between the SN stretching and the ND₂ bending vibrations.