An Unexpected Effect of the Nature of the Collision Gas in Collisional Activation Mass Spectrometry

✍ Scribed by Robert Flammang; Laurence Gallez; Yves Van Haverbeke; Ming Wah Wong; Curt Wentrup

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 276 KB
• Volume: 10
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19960131)10:2<232::aid-rcm471>3.0.co;2-d

✦ Synopsis

Radical-cations a-c with the structure H N U X @=O, NH, S respectively) have been studied by collisionalactivation (CA) mass spectrometry using Merent target gases (helium, oxygen and nitrogen). An unusual effect of the nature of the collision gas has been noted for oxygen which induces a very intense loss of a nitrogen atom for ions a and b, but not for ion c. The replacement of the NH hydrogen by a methyl group suppresses this effect. Oxygen therefore appears to induce an isomerization of ions a and b into nitrene isomers a' and b' (N-CHGX). The use of nitrogen, which gives essentially the same CA spectra as helium, eliminates the possibility of an effect based on the center-of-mass collision energy. G2(MP2) calculations indicate that the nitrene radicalcations lie close in energy to the cumulene ions when X=O or NH.