Title

Characterization of Uranyl Coordinated by Equatorial Oxygen: Oxo in UO versus Oxyl in UO

DOI

10.1021/acs.jpca.1c03818

Document Type

Journal Article

Publication Date

7-1-2021

Publication Title

The journal of physical chemistry. A

Volume

125

Issue

25

First Page

5544

Last Page

5555

Abstract

Uranium trioxide, UO, has a T-shaped structure with bent uranyl, UO, coordinated by an equatorial oxo, O. The structure of cation UO is similar but with an equatorial oxyl, O. Neutral and cationic uranium trioxide coordinated by nitrates were characterized by collision induced dissociation (CID), infrared multiple-photon dissociation (IRMPD) spectroscopy, and density functional theory. CID of uranyl nitrate, (complex ), eliminates NO to produce nitrate-coordinated UO, (), which ejects NO to yield UO in (). Finally, associates with HO to afford uranyl hydroxide in (). IRMPD of , , and confirms uranyl equatorially coordinated by nitrate(s) along with the following ligands: () radical oxyl O; () oxo O; and () two hydroxyls, OH. As the nitrates are bidentate, the equatorial coordination is six in , five in , four in , and three in . Ligand congestion in low-coordinate suggests orbital-directed bonding. Hydrolysis of the equatorial oxo in epitomizes the inverse trans influence in UO, which is uranyl with inert axial oxos and a reactive equatorial oxo. The uranyl ν IR frequencies indicate the following donor ordering:

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