Mass Spectra and Ion Chemistry of Methylphosphine, Dimethylphosphine and Dimethyldeuterophosphine, Investigated by Ion Cyclotron Resonance Spectrometry

Abstract

The mass spectra and the ion molecule reactions of methylphosphine, dimethylphosphine and dimethyldeuterophosphine have been studied by ion cyclotron resonance spectrometry. About 50 ion molecule reaction are observed for each compound. The product ions can be classified as ions with two phosphorus atoms: P 2 R 5 + , P 2 R 3 + , P 2 R 2 + and P 2 R + (R = CH 3 or H), as phosphonium and phosphinium ions and ions resulting from collision dissociations and charge exchange reactions. Tertiary ions with three phosphorus atoms like CH 3 P 3 H 2 + (from CH 3 PH 2 ) and (CH 3 ) 4 P 3 H 2 (from (CH 3 ) 2 PH) have also been detected. The mechanisms of the ion molecule reactions, rearrangements, P -H- and C-H-reactivities and product ion structures are discussed, using in the case of dimethylphosphine the results obtained with the deuterated compound. Rate constants of formation of the more abundant product ions from the molecular ion and the CH 3 P + ion, both odd electron particles, have been determined. The reactions with dimethylphosphine have much smaller rate constants than the reactions with methylphosphine.