Generation of the elusive methyl dioxophosphorane molecule, CH3P(O)2, by delayed dissociation of selected precursors

A recent flame-sampling laser-ionization study [Chem. Phys. Lett. 275 (1997) 278] reported that combustion of dimethyl methyl phosphonate generates the elusive CH3P(O)2 molecule and that it has an ionization energy (IE) of 9.24±0.01 eV. Ab initio calculations (CBS-QB3 level of theory) indicate that this IE is that of the ‘enol’ tautomer CH2P(O)OH, while that of CH3P(O)2 is much higher, 11.66 eV. We propose that in the above experiments, a trace amount of the ‘enol’ is co-generated with the ‘keto’ isomer CH3P(O)2. Mass spectrometric experiments involving Neutralization–Reionization (NR) and Collision-Induced Dissociative Ionization (CIDI) show that CH2P(O)OH and CH3P(O)2 are both stable neutral species in the dilute gas-phase.