Synthesis and electronic structure determination of uranium(vi) ligand radical complexes

Abstract

(1c), were prepared and the electronic structure of the oneelectron oxidized species [1a-c] + were investigated in solution. The solid-state structures of 1a and 1b were solved by X-ray crystallography, and in the case of 1b an asymmetric UO2 2+ unit was found due to an intermolecular hydrogen bonding interaction. Electrochemical investigation of 1a-c by cyclic voltammetry showed that each complex exhibited at least one quasi-reversible redox process assigned to the oxidation of the phenolate moieties to phenoxyl radicals. The trend in redox potentials matches the electron-donating ability of the para-phenolate substituents. The electron paramagnetic resonance spectra of cations

Theoretical investigation into the coordination of R‐/S‐asymmetric uranyl–salophens containing six‐membered ring lactam with cis−/trans‐cyclohexylamines

“…The pseudopotential basis set was used to calculate for heavy metals by using the “genecp” keyword in Gaussian 09 software. The quasi‐relativistic small‐core pseudopotential ECP60MWB basis set was used for U, and the 6‐311G** basis set was used for C, H, O and N. Based on the B3LYP method of DFT, calculations were performed for all the receptors, the guests and the coordination complexes. There was no imaginary frequency in the normal mode data given by the frequency calculation, which showed that the geometry of the optimized complexes was in the most reasonable structure with the lowest energy.…”

Uranyl‐Bound Tetra‐Dentate Non‐Innocent Ligands: Prediction of Structure and Redox Behaviour Using Density Functional Theory

“…[18] of this article for further details). Likewise, oxidation of a series of uranyl‐salophen complexes have recently been determined to form ligand radical compounds, and a tetrathiafulvalene‐salphen uranyl complex has been confirmed by theory and experiment to produce radical species during oxidation of the complex . Although in certain cases oxidation of uranyl(VI) compounds has resulted in oxidation of the coordinating ligand and produced radical species, these may not always undergo or induce further chemical transformations.…”

“…Similarly, a range of transition metal (TM) coordination complexes of tetra‐dentate organic ligands, such as ‘salen’ and ‘saloph’, have been reported to exhibit non‐innocent behaviour during the electrochemical oxidation process (see ref. [18] of this article for further details).…”

“…Also, a recently reported cyclic voltammetry study of a uranyl-dimer containing Ar-BIANs (N,N'bis[(aryl)imino]acenaphthenes) ligands has revealed the participation of the ligand in the redox event. [26] Similarly, a range of transition metal (TM) coordination complexes of tetra-dentate organic ligands, such as 'salen' and 'saloph', have been reported to exhibit non-innocent behaviour during the electrochemical oxidation process [27] (see ref. [18] of this article for further details).…”

“…However, these coordinating ligands of TM complexes are preferentially oxidized despite the presence of d-electrons on the metal cation. [16] [27] In this work we shall use DFT to study the uranyl(VI/V) reduction potentials of uranyl-salmnt complexes (UO 2 -salmnt-L) in DCM solution recently experimentally determined by Hardwick et al [30] The 'salmnt' ligand is a tetra-dentate Schiff base ligand and it occupies the equatorial plane of the uranyl ion, with the fifth coordination site of the uranyl ion is available for a mono-dentate ligand. This coordination mode of the 'salmnt' ligand with the uranyl ion is shown in Figure 1.…”