Protonated methyl nitrite. A theoretical investigation on the structure and stability of (MeO-NOH+ and the proton affinity of RO-NO (R=H, Me)

Ab initio calculations have been performed on the structure and stability of(MeO-NOH+ and the proton affinity (PA) of RO-NO (R = H, Me). At the MP4/6-311G**//MP2(FULL)/6-31G* level of theory, the ion-dipole adduct MeOH-NO+ 1 is by far the most stable protomer. At the G2 level, the dissociation enthalpy into MeOH and NO+ is computed as 25.3 kcal mol(-1) and the PAs of MeO-NO and HO-NO amount to 187 and 188 kcal mol(-1), respectively. This finding marks a departure from the expected order and parallels the anomalous trend recently ascertained in the PAs of the strictly related RO-NO2 (R = H, Me).