Collision-induced dissociation of [UO (NO )(O )] and reactions of product ions with H O and O

Amanda R. Bubas, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania, USA.
Evan Perez, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania, USA.
Luke J. Metzler, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania, USA.
Scott D. Rissler, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania, USA.
Michael J. Van Stipdonk, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania, USA.

Abstract

We recently reported a detailed investigation of the collision-induced dissociation (CID) of [UO (NO ) ] and [UO (NO ) (O )] in a linear ion trap mass spectrometer (J. Mass Spectrom. DOI:10.1002/jms.4705). Here, we describe the CID of [UO (NO )(O )] which is created directly by ESI, or indirectly by simple elimination of O from [UO (NO )(O ) ] . CID of [UO (NO )(O )] creates product ions as at m/z 332 and m/z 318. The former may be formed directly by elimination of O , while the latter required decomposition of a nitrate ligand and elimination of NO . DFT calculations identify a pathway by which both product ions can be generated, which involves initial isomerization of [UO (NO )(O )] to create [UO (O)(NO )(O )] , from which elimination of NO or O will leave [UO (O)(O )] or [UO (O)(NO )] , respectively. For the latter product ion, the composition assignment of [UO (O)(NO )] rather than [UO (NO )] is supported by ion-molecule reaction behavior, and in particular, the fact that spontaneous addition of O , which is predicted to be the dominant reaction pathway for [UO (NO )] is not observed. Instead, the species reacts with H O, which is predicted to be the favored pathway for [UO (O)(NO )] . This result in particular demonstrates the utility of ion-molecule reactions to assist the determination of ion composition. As in our earlier study, we find that ions such as [UO (O)(NO )] and [UO (O)(O )] form H O adducts, and calculations suggest these species spontaneously rearrange to create dihydroxides.