Phosphorus Analogues of Methyl Nitrite and Nitromethane: CH3OPO and CH3PO2

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).