The Photochemical Behavior of the Uranyl Ion (UO): a Dimer Perspective and Outlook

✍ Scribed by Christiane Görller-Walrand; Kelly Servaes

• Book ID: 102858848
• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: German
• Weight: 520 KB
• Volume: 92
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200900159

✦ Synopsis

Abstract

The complex formation of uranyl (UO$\rm{ {_{2}^{2+}}}$) with oxalic acid (HOOCCOOH) in acetone is studied by UV/VIS, absorption, luminescence, and excitation spectroscopy. Based on solid‐state crystallographic data, we propose a dimer structure with D~2h~ symmetry for the complex in solution. This symmetry is vibrationally distorted to D~2~ by the out‐of‐plane equatorial‐ligand vibration. From the spectroscopic point of view, this vibration induces intensity in the transitions Π~g~←Σ$\rm{{_{g}^{+}}}$ and one component of Δ~g~←Σ$\rm{ {_{g}^{+}}}$. From the photochemical point of view, this vibration induces a twisting mechanism that destroys the complex. From the theoretical point of view, it is worthwhile to notice that the symmetry of the odd out‐of‐plane vibration is the same as the symmetry of the odd LUMO (f~xyz~). By vibrating accordingly to the LUMO symmetry, the complex is self‐destroying by absorption of light, and the uranyl is regenerated. A small comment is devoted to a possible δ–δ interaction and the quintuple U~2~ bond distance proposed by Gagliardi and Ross [29].