Spectroscopy of acyl and carbonyl isocyanates

Article abstract of DOI:10.1016/0584-8539(94)80059-6

The gas phase IR, gas phase UV and solution 13C NMR spectroscopic data for seven carbonyl isocyanates X-CO-NCO and eight acyl isocyanates R-CO-NCO are reported.The IR group frequencies are assigned and substituent-frequency relationships are given for the C=O and NCO stretching frequencies.For carbonyl isocyanates the IR spectra show features of isomeric nonuniformity which are interpreted in terms of cisoid and transoid conformations.For all acyl isocyanates the IR spectra suggest the presence of the cisoid conformation only. ? -> ? and n -> ? transitions are assigned for the gas phase UV spectra and the 13C chemical shifts for the carbonyl and isocyanato carbons are reported.Generalized spectroscopic data, together with theoretical data, indicate a small degree of resonance interaction between the carbonyl and isocyanato groups.