Characterization of ammonia phosphorus oxide H3NPO+ ions and their neutralcounterparts by mass spectrometry and computational chemistry

Dissociative electron ionization of O, S-dimethyl acetylphosphoramidothioat e yields [N, H-3, P, O](+) ions at m/z 64 whose structure was investigated by tandem mass spectrometry in combination with electronic structure calcul ations. Collisional activation mass spectra of source generated and low ene rgy (MS/MS/MS) m/z 64 ions suggest that the majority of the m/z 64 ions pos sess the connectivity NH3PO+ (1). Neutralization-reionisation experiment on m/z 64 ions indicates that NH3PO. is a viable species in the gas phase. Th e relative energies of the ions and neutrals of the two isomeric species, N H3PO+/. (1) and NH2POH+/. (2) corresponding to the [N, H-3, P, O](+/.) pote ntial energy surface and the fragmentation energies calculated at B3LYP/6-3 1G** level is used to support the interpretation of experimental results. ( C) 2001 Elsevier Science B.V.