Phosphorus Analogues of Methyl Nitrite and Nitromethane: CH₃OPO and CH₃PO₂

Abstract

Methoxyphosphinidene oxide (CH3OPO) and isomeric methyldioxophosphorane (CH3PO2) are key intermediates in the degradation of organophosphorus compounds (OPCs). Unlike the nitrogen analogues CH3ONO and CH3NO2, the experimental data for these two prototypical OPCs are scarce. By high‐vacuum flash pyrolysis (HVFP) of the diazide CH3OP(O)(N3)2 at 1000 K, the cis and trans conformers of CH3OPO have been generated in the gas phase and subsequently isolated in cryogenic Ar and N2 matrices for IR spectroscopic characterization. Upon 266 nm laser irradiation of CH3OPO, cis→trans conformational conversion occurs with concurrent isomerization to CH3PO2. The spectroscopic identification of CH3OPO and CH3PO2 is supported by D‐, 13C‐, and 18O‐isotope labeling and quantum chemical calculations at the CCSD(T)‐F12a/cc‐pVTZ‐F12 level using configuration‐selective vibrational configuration interaction (VCI).

Spectroscopic Identification and Photochemistry of Astrochemically Relevant Phosphorus-bearing Molecules [O, C, N, P] and [2O, C, N, P]

“…c Not observed.The strongest band at 1472.1 cm −1 for 5 belongs to the asymmetric stretching mode of PO 2 (cal. 1478.8 cm −1 ), which is close to that of O 2 PF (1467.8 cm −1 , Ar matrix;Chu et al 2019), but largely blueshifted in comparison with other organic dioxophosphoranes such as CH 3 PO 2 (1401.9 cm −1 , Ar matrix;Zhao et al 2019a) and PhPO 2 (1416 cm −1 , Ar matrix;Mardyukov et al 2017). The symmetric stretching mode appears at 1150.9 cm −1 (cal.…”