An ab initio study of the fulminate anion cyanate anion rearrangement: Possible intermediacy of the oxazirinyl anion

The rearrangement of the fulminate anion (CNO-) to the cyanate anion (OCN-) has been studied with high-level ab initio methods. Geometry optimizations have been carried out at HF, MPn (n = 2-4), QCISD, QUISD(T), BD and BD(T) levels using the 6-31+G(d) basis set. The highest level of theory for the calculation of relative energies is QCISD(T)/6-311+G(3df, 2p). Results show that the rearrangement proceeds via an oxazirinyl anion intermediate, which is separated by barriers of 52.8 and 18.4 kJ mol(-1) from CNO- and OCN-, respectively.