The elusive methene ylides CH2CIH, CH2FH and CH2OH2

Abstract

AbstractThe possible existence of the ylides CH2CIH, CH25FH and CH2OH2 as stable neutral species in the gas phase has been investigated by the neutralization–reionization (NR) mass spectrometry of their radical cations using a double‐focusing mass spectrometer of reversed geometry. The experiments were, for the most part, performed under single‐collision conditions with Xe as the neutralization target gas and He and O2 as reionization agents. For each ylidion a peak was observed in their NR mass spectrum which indicated that the neutral ylide had apparently been produced. However for CH2FH+˙ and CH2OH2+˙ the m/z 34 and m/z 32 peaks, respectively, were attribut‐able to interferences from the natural isotopic abundance of ions of lower mass. For CH2CIH+˙, the NR recovery signal was found to arise from the presence of CH3CI+˙ as an impurity in the ylidion flux. This was proved by examination of the collisional activation mass spectra of the [C, H3, CI]+˙ ions produced in the NR mass spectra of the conventional ions and ylidions, an experiment performed using a triple‐sector mass spectrometer.