The nitrosyl isocyanate (ONNCO) has been generated from a heterogeneous reaction of gaseous nitrosyl chloride
with silver isocyanate and studied for the first time in the gas phase. This structurally and energetically novel
transient specimen is characterized by HeI photoelectron spectroscopy combined with DFT calculations. Both the
calculations and the spectroscopic results suggest that the molecule adopts an open-chain trans structure. The
observed decomposition products indicate the formation of ONNCO and further confirm the previously reported
decomposition pathway