THE IDENTIFICATION OF DISTONIC RADICAL CATIONS ON THE BASIS OF A REACTION WITH DIMETHYL DISULFIDE

A novel bimolecular reaction selective for radical cations with spatially separated radical and charge sites (distonic ions) is reported. Gas-phase reactions of dimethyl disulfide with radical cations containing oxygen functionalities were studied in a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer. Conventional radical cations (generated by removing an electron from a stable neutral molecule), as well as enol radical cations, undergo fast charge exchange with dimethyl disulfide. However, distonic radical cations abstract CH3S. from dimethyl disulfide (the reaction is often accompanied by charge exchange). Related even-electron cations are unreactive toward dimethyl disulfide. Hence, the observation of CH3S. abstraction is indicative of a distonic ion structure. This approach was used to identify two distonic ions formed in ion-molecule reactions involving other distonic ions. One of these product ions is a novel sulfur-containing distonic ion: (CH3)2S+-CH2.