Hydroxy- and alkoxy-bridged dinuclear uranyl–Schiff base complexes: hydrolysis, transamination and extraction studies

Abstract

The reaction of uranyl nitrate with 1,3-bis(salicylideneamino)-2-propanol (H(3)L1) and 1,3-bis(3,5-di-tert-butylsalicylideneamino)-2-propanol (H(3)L2) in the presence of triethylamine (Et(3)N) yielded hydroxy- and alkoxy-bridged dinuclear complexes; [(UO(2))(2)(L1)(OH)(MeOH)(2)].(MeOH)(2) (.(MeOH)(2)) and [(UO(2))(2)(L2)(OH)(MeOH)(2)].(MeOH)(2) (.(MeOH)(2)). The crystal structures of .(DMF)(2) and .(DMF)(2) exhibit an unsymmetrical central U(2)O(2) core involving bridging alkoxy- and hydroxy-oxygen atoms. The geometry around the uranium center in .(DMF)(2) and .(DMF)(2) is that of a distorted pentagonal bipyramid with the solvent molecule occupying the fifth coordination site. The flexible nature of the ligand backbone is more pronounced in .(DMF)(2) compared to .(DMF)(2), yielding two molecules per unit cell in different conformations. Under similar reaction conditions, using ethylenediamine as a base, the respective Salen-based uranyl compounds, [UO(2)(Salen)(MeOH)] () and [UO(2)(Bu(t)(2)-Salen)(MeOH)] () are obtained due to transamination of the ligand backbone. Complexes .(MeOH)(2) and .(MeOH)(2) when reacted with an excess of ethylenediamine failed to yield the respective Salen-based complexes, and , respectively. The new compounds have been characterized using solution (NMR and UV-Vis) and solid-state (IR, X-ray crystallography) techniques. Hydrolysis of .(MeOH)(2) and .(MeOH)(2) in the pH range 1-14 was studied using UV-Vis spectroscopy and compared with the hydrolysis of and [UO(2)(Salophen)(MeOH)] (). A two-phase extraction study suggests quantitative removal of uranyl ions from the aqueous phase at higher pH conditions.

Di‐μ‐acetato Diuranyl(VI) Complexes with N‐(2‐pyridyl)‐N′‐(5‐R‐salicylidene)hydrazines: Syntheses, Structures, Properties and Extraction Studies

“…The maximum extents of extraction in the above mentioned two‐phase extraction studies are very good (> 90%) in both methods. These results are better or comparable to the previously reported extraction studies using Schiff bases ,,…”

Structural elucidation and physicochemical properties of mononuclear Uranyl(VI) complexes incorporating dianionic units

“…The medium intensity peak owing to ν (C-O) vibration appears at 1205 cm −1 and 1204 cm −1 in complex 1 and 2, respectively17. Asymmetric stretching vibrations due to UO 2 2+ cation appears at 894 cm −1 and 905 cm −1 for complex 1 and complex 2, respectively1819, and the remaining bands were found at their expected positions.…”

Synthesis and crystal structures of two isostructural manganese(III) and iron(III) complexes derived from N,N′-bis(3-ethoxysalicylidene)-1,2-propanediamine with cytochrome P450-like hydroxylation properties

“…These complexes play an important role in the development of coordination chemistry related to catalysis and enzymatic reactions, magnetism, and molecular architectures [1][2][3]. The hydroxylation of unactivated alkenes is one of the most remarkable reactions because of the thermodynamics of the process [4][5][6].…”

“…Previously, we have reported two copper(II) complexes as the catalysts for hydroxylation of cyclohexene [7]. In order to seek more efficient and stable catalysts for the reaction, in this work, two mononuclear Schiff base manganese(III) and iron(III) complexes with the formula [M III L(N 3 )(OH 2 )] 9 1/2N 2 (M = Mn for (1) and Fe for (2); H 2 L = N,N 0 -bis(3-ethoxysalicylidene)-1,2-propanediamine) have been synthesized and structurally characterized. The catalytic properties for the dioxygen oxidation of cyclohexene have been studied.…”