Photochemical Synthesis and Characterization of a Uranyl Peroxide Triethylamine N‐OxideDimer

A μ‐peroxido‐bis[di‐triethylamine N‐oxide‐dichloro‐dioxouranium] complex with the formula [(UO 2 ) 2 O 2 (ON(CH 2 CH 3 ) 3 ) 4 Cl 2 ] (complex 1 ) was synthesized photochemically from a reaction containing uranyl chloride, triethylamine, and H 2 O 2 . The photochemical breakdown of H 2 O 2 yielded ⋅OH radicals that reacted with triethylamine to form triethylamine N‐oxide (TEAO) in situ , which subsequently coordinated to UO 2 2+ cations in a monodentate fashion via the N‐oxide functional groups. Structure determination using single crystal X‐ray diffraction revealed that TEAO ligands also formed intermolecular and intramolecular hydrogen bonds with UO 2 2+ and peroxide moieties, and the intermolecular H‐bonding interactions displayed a temperature dependence with O yl ‐ ‐ H−C and O per ‐ ‐ H−C distances shortening at 100(2) K by ca. 0.1 Å. Raman spectroscopy data were collected on single crystals of 1 and peak fitting of these results allowed for assignments of peaks including C−N stretches for TEAO ligands bound to UO 2 2+ cations at 696.8 cm −1 , 717.8 cm −1 , and 776.5 cm −1 , which are redshifted by 30–40 cm −1 when compared to free triethylamine. UO 2 2+ ν 1 and O 2 2− ν 1 stretches, U−O per stretches, and notably, U−Cl stretches were all identified as well, with U−Cl modes at 198.9 cm −1 and 212.1 cm −1 substantially redshifted compared to the uranyl chloride starting material.