THE PROTOTYPICAL ORGANOPHOSPHORUS YLIDION CENTER-DOT-CH2PH3+

The reactivity of the prototypical phosphorus-containing ylidion (alph a-distonic ion) (CH2PH3+)-C-. has been investigated in the gas phase b y using a dual cell Fourier-transform ion cyclotron resonance mass spe ctrometer. The ion (CH2PH3+)-C-. and its more stable conventional isom er CH3PH2.+ show distinctly different reactivities toward neutral reag ents. This observation contrasts the facile interconversion of the ana logous sulfur- and oxygen-containing distonic ions (CH2SH2+)-C-. and ( CH2OH2+)-C-. with their conventional isomers CH3OH.+ and CH3SH.+, resp ectively, within collision complexes in the gas phase. Bracketing expe riments yield a proton affinity of 190.4 +/- 3 kcal mol(-1) for the ph osphorus atom in (CH2PH2)-C-.. Together with a calculated heat of form ation for (CH2PH2)-C-., this value yields a heat of formation of 217 /- 3 kcal mol(-1) (at 298 K) for the distonic ion (CH2PH3+)-C-..