Leavitt, Christopher M. and Bryantsev, Vyacheslav S. and de Jong, Wibe A. and Diallo, Mamadou S. and Goddard, William A., III and Groenewald, Gary S. and Van Stipdonk, Michael J. (2009) Addition of H_2O and O_2 to Acetone and Dimethylsulfoxide Ligated Uranyl(V) Dioxocations. Journal of Physical Chemistry A, 113 (11). pp. 2350-2358. ISSN 1089-5639 http://resolver.caltech.edu/CaltechAUTHORS:20090825-132255812
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Gas-phase complexes of the formula [UO_2(lig)]^+ (lig = acetone (aco) or dimethylsulfoxide (dmso)) were generated by electrospray ionization (ESI) and studied by tandem ion-trap mass spectrometry to determine the general effect of ligand charge donation on the reactivity of UO_2^+ with respect to water and dioxygen. The original hypothesis that addition of O_2 is enhanced by strong σ-donor ligands bound to UO_2^+ is supported by results from competitive collision-induced dissociation (CID) experiments, which show near exclusive loss of H_2O from [UO_2(dmso)(H_2O)(O_2)]^+, whereas both H_2O and O_2 are eliminated from the corresponding [UO_2(aco)(H_2O)(O_2)]^+ species. Ligand-addition reaction rates were investigated by monitoring precursor and product ion intensities as a function of ion storage time in the ion-trap mass spectrometer: these experiments suggest that the association of dioxygen to the UO_2^+ complex is enhanced when the more basic dmso ligand was coordinated to the metal complex. Conversely, addition of H_2O is favored for the analogous complex ion that contains an aco ligand. Experimental rate measurements are supported by density function theory calculations of relative energies, which show stronger bonds between UO_2^+ and O_2 when dmso is the coordinating ligand, whereas bonds to H_2O are stronger for the aco complex.
|Additional Information:||Copyright © 2009 American Chemical Society. Received: August 27, 2008; Revised Manuscript Received: December 19, 2008. Publication Date (Web): February 13, 2009. Work by M. J. Van Stipdonk and C. M. Leavitt was supported through a grant from the U.S. National Science Foundation (NSF grant CAREER-0239800). Work by G. S. Groenewold was supported by the U.S. Department of Energy, INL Laboratory Directed Research & Development Program under DOE Idaho Operations Office Contract DE AC07 05ID14517. Funding for this work was provided by the National Science Foundation (NIRT CTS Award # 0506951) and by the US Environmental Protection Agency (STAR Grant RD-83252501). Work by V. S. Bryantsev, M. S. Diallo, and W. A. Goddard, III, is performed in part using the MSCF in EMSL, a national scientific user facility sponsored by the U.S. DOE, OBER and located at PNNL. W. A. de Jong’s research was supported by the BES Heavy Element Chemistry program of the U.S. Department of Energy, Office of Science, and was performed in part using the Molecular Science Computing Facility in the William R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the U.S. Department of Energy’s Office of Biological and Environmental Research located at the Pacific Northwest National Laboratory, which is operated for the Department of Energy by Battelle. Supporting Information: Tables showing the effect of the basis set size on binding energies, listing electronic binding energies, geometric parameters and frequencies for 1−12 calculated at the B3LYP/SSC/6-311++G^(**) level of theory, and Cartesian coordinates and energies (Hartrees) for the M06-L/SSC/6-311++G^(**) optimized geometries. This material is available free of charge via the Internet at http://pubs.acs.org.|
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|Deposited By:||George Porter|
|Deposited On:||09 Sep 2009 18:01|
|Last Modified:||26 Dec 2012 11:15|
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