Gas‐phase Ion–Molecule Reactions of Trimethyl Phosphite with the Phosphonium Ion OP(OCH3)2 in a Quadrupole Ion Trap

Abstract

The gas-phase ion–molecule reactions of the phosphonium ion OP(OCH3)2+ formed by electron impact with neutral trimethyl phosphite were studied with the use of a quadrupole ion trap (QIT) mass spectrometer. Observed reactions include competing methoxy transfers between OP(OCH3)2+ and the neutral species to yield a phosphenium ion :P(OCH3)2+ or a tetracoordinate phosphorus ion P(OCH3)4+. Background water in the QIT gives an adduct with OP(OCH3)2+ which protonates neutral trimethyl phosphite, as shown by triple mass spectrometric experiments. High-level ab initio calculations and chemical ionization reactions were performed to investigate the unimolecular loss of methanol from protonated trimethyl phosphite. © 1997 by John Wiley & Sons, Ltd.