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Bubas AR, Tatosian IJ, Iacovino A, Corcovilos TA, van Stipdonk MJ. Reactions of gas-phase uranyl formate/acetate anions: reduction of carboxylate ligands to aldehydes by intra-complex hydride attack. Phys Chem Chem Phys 2024; 26:12753-12763. [PMID: 38619367 DOI: 10.1039/d4cp00823e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
In a previous study, electrospray ionization, collision-induced dissociation (CID), and gas-phase ion-molecule reactions were used to create and characterize ions derived from homogeneous precursors composed of a uranyl cation (UVIO22+) coordinated by either formate or acetate ligands [E. Perez, C. Hanley, S. Koehler, J. Pestok, N. Polonsky and M. Van Stipdonk, Gas phase reactions of ions derived from anionic uranyl formate and uranyl acetate complexes, J. Am. Soc. Mass Spectrom., 2016, 27, 1989-1998]. Here, we describe a follow-up study of anionic complexes that contain a mix of formate and acetate ligands, namely [UO2(O2C-CH3)2(O2C-H)]- and [UO2(O2C-CH3)(O2C-H)2]-. Initial CID of either anion causes decarboxylation of a formate ligand to create carboxylate-coordinated U-hydride product ions. Subsequent CID of the hydride species causes elimination of acetaldehyde or formaldehyde, consistent with reactions that include intra-complex hydride attack upon bound acetate or formate ligands, respectively. Density functional theory (DFT) calculations reproduce the experimental observations, including the favored elimination of formaldehyde over acetaldehyde by hydride attack during CID of [UO2(H)(O2C-CH3)(O2C-H)]-. We also discovered that MSn CID of the acetate-formate complexes leads to generation of the oxyl-methide species, [UO2(O)(CH3)]-, which reacts with H2O to generate [UO2(O)(OH)]-. DFT calculations support the observation that formation of [UO2(O)(OH)]- by elimination of CH4 is favored over H2O addition and rearrangement to create [UO2(OH)2(CH3)]-.
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Affiliation(s)
- Amanda R Bubas
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, PA 15282, USA.
| | - Irena J Tatosian
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, PA 15282, USA.
| | - Anna Iacovino
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, PA 15282, USA.
| | - Theodore A Corcovilos
- Department of Physics, Duquesne University, 600 Forbes Ave, Pittsburgh, PA 15282, USA
| | - Michael J van Stipdonk
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, PA 15282, USA.
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Tatosian I, Bubas A, Iacovino A, Kline S, Metzler L, Van Stipdonk M. Formation and hydrolysis of gas-phase [UO 2 (R)] + : R═CH 3 , CH 2 CH 3 , CH═CH 2 , and C 6 H 5. J Mass Spectrom 2019; 54:780-789. [PMID: 31426122 DOI: 10.1002/jms.4430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/05/2019] [Accepted: 08/12/2019] [Indexed: 06/10/2023]
Abstract
The goals of the present study were (a) to create positively charged organo-uranyl complexes with general formula [UO2 (R)]+ (eg, R═CH3 and CH2 CH3 ) by decarboxylation of [UO2 (O2 C─R)]+ precursors and (b) to identify the pathways by which the complexes, if formed, dissociate by collisional activation or otherwise react when exposed to gas-phase H2 O. Collision-induced dissociation (CID) of both [UO2 (O2 C─CH3 )]+ and [UO2 (O2 C─CH2 CH3 )]+ causes H+ transfer and elimination of a ketene to leave [UO2 (OH)]+ . However, CID of the alkoxides [UO2 (OCH2 CH3 )]+ and [UO2 (OCH2 CH2 CH3 )]+ produced [UO2 (CH3 )]+ and [UO2 (CH2 CH3 )]+ , respectively. Isolation of [UO2 (CH3 )]+ and [UO2 (CH2 CH3 )]+ for reaction with H2 O caused formation of [UO2 (H2 O)]+ by elimination of ·CH3 and ·CH2 CH3 : Hydrolysis was not observed. CID of the acrylate and benzoate versions of the complexes, [UO2 (O2 C─CH═CH2 )]+ and [UO2 (O2 C─C6 H5 )]+ , caused decarboxylation to leave [UO2 (CH═CH2 )]+ and [UO2 (C6 H5 )]+ , respectively. These organometallic species do react with H2 O to produce [UO2 (OH)]+ , and loss of the respective radicals to leave [UO2 (H2 O)]+ was not detected. Density functional theory calculations suggest that formation of [UO2 (OH)]+ , rather than the hydrated UV O2 + , cation is energetically favored regardless of the precursor ion. However, for the [UO2 (CH3 )]+ and [UO2 (CH2 CH3 )]+ precursors, the transition state energy for proton transfer to generate [UO2 (OH)]+ and the associated neutral alkanes is higher than the path involving direct elimination of the organic neutral to form [UO2 (H2 O)]+ . The situation is reversed for the [UO2 (CH═CH2 )]+ and [UO2 (C6 H5 )]+ precursors: The transition state for proton transfer is lower than the energy required for creation of [UO2 (H2 O)]+ by elimination of CH═CH2 or C6 H5 radical.
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Affiliation(s)
- Irena Tatosian
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, Pennsylvania, 15282, USA
| | - Amanda Bubas
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, Pennsylvania, 15282, USA
- Department of Chemistry, University of Utah, 215 1400 E, Salt Lake City, UT, 84112
| | - Anna Iacovino
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, Pennsylvania, 15282, USA
| | - Susan Kline
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, Pennsylvania, 15282, USA
| | - Luke Metzler
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, Pennsylvania, 15282, USA
| | - Michael Van Stipdonk
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, Pennsylvania, 15282, USA
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Van Stipdonk MJ, Iacovino A, Tatosian I. Influence of Background H 2O on the Collision-Induced Dissociation Products Generated from [UO 2NO 3]<sup/>. J Am Soc Mass Spectrom 2018; 29:1416-1424. [PMID: 29654536 DOI: 10.1007/s13361-018-1947-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 03/18/2018] [Accepted: 03/18/2018] [Indexed: 06/08/2023]
Abstract
Developing a comprehensive understanding of the reactivity of uranium-containing species remains an important goal in areas ranging from the development of nuclear fuel processing methods to studies of the migration and fate of the element in the environment. Electrospray ionization (ESI) is an effective way to generate gas-phase complexes containing uranium for subsequent studies of intrinsic structure and reactivity. Recent experiments by our group have demonstrated that the relatively low levels of residual H2O in a 2-D, linear ion trap (LIT) make it possible to examine fragmentation pathways and reactions not observed in earlier studies conducted with 3-D ion traps (Van Stipdonk et al. J. Am. Soc. Mass Spectrom. 14, 1205-1214, 2003). In the present study, we revisited the dissociation of complexes composed of uranyl nitrate cation [UVIO2(NO3)]+ coordinated by alcohol ligands (methanol and ethanol) using the 2-D LIT. With relatively low levels of background H2O, collision-induced dissociation (CID) of [UVIO2(NO3)]+ primarily creates [UO2(O2)]+ by the ejection of NO. However, CID (using He as collision gas) of [UVIO2(NO3)]+ creates [UO2(H2O)]+ and UO2+ when the 2-D LIT is used with higher levels of background H2O. Based on the results presented here, we propose that product ion spectrum in the previous experiments was the result of a two-step process: initial formation of [UVIO2(O2)]+ followed by rapid exchange of O2 for H2O by ion-molecule reaction. Our experiments illustrate the impact of residual H2O in ion trap instruments on the product ions generated by CID and provide a more accurate description of the intrinsic dissociation pathway for [UVIO2(NO3)]+. Graphical Abstract ᅟ.
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Affiliation(s)
- Michael J Van Stipdonk
- Department of Chemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA.
| | - Anna Iacovino
- Department of Chemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
| | - Irena Tatosian
- Department of Chemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
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