This review summarizes significant contributions reported on aminophosphine oxides (AmPOs), specifically those containing at least one amino group present as amino substituents on α- and β-carbons including direct P-N bond containing molecules. AmPOs have additional 'N' site(s), including highly basic 'P=O' groups, and these features make favor smooth and unexpected behavior. The most striking manifestations of flexibility of AmPOs are that they are exciting ligand systems for the coordination chemistry of actinides, and their involvement in catalytic organic reactions including enantioselective opening of meso-epoxides, addition of silyl enol ethers, allylation with allyltributylstannane, etc. The diverse properties of the AmPOs and their metal complexes demonstrate both the scope and complexity of these systems, depending on the basicity of phosphoryl group, and nature of the substituents on the pentavalent tetracoordinate phosphorus atom and metal. Two components key to understanding the challenges of actinide separations are detailed here, namely, previously described separation methods, and recent investigations into the fundamental coordination chemistry of actinides. Both are aimed at probing the critical features necessary for improved selectivity of separations. This review leads to the conclusion that, although many AmPOs have already been discovered and developed over the past century, many opportunities nevertheless exist for further developments towards new extraction processes and new catalytic materials by fine tuning the electronic and steric properties of substituents on the central phosphorus atom.
The extraction behavior of U(vi) & Am(iii) with di-n-alkyl phosphine oxides (DAPOs) was investigated. DAPO behaves like an acidic extractant at low acidity and at higher acidity they extracted via cation exchange mechanism.
A series of bisphosphoramides of the type R2P(O)NHCH2CH2NHP(O)R2 (L) (where R=n‐butyl, n‐hexyl, n‐octyl, ethoxy, phenyl) is synthesized in two‐steps by Atherton‐Todd reaction of ethylenediamine and H‐phosphonate derived from the reaction of diethylphosphite and the Grignard reagent. These ligands were employed in the preparation of La(III) and Th(IV)complexes of the general type [LaCl3(L)2]n and [Th(NO3)4Th(IV)2]. Notably, La(III) complexes of bisphosphoramides are found as infinite coordination polymers with bridging phosphine oxide ligands in an intermolecular fashion. In contrast, Th(IV) complexes are formed with two chelating bisphosphoramide ligands around the metal center intramolecularly. All these ligands and the corresponding metal complexes are characterized by spectroscopic and analytical data. The single‐crystal X‐ray analyses of lanthanum and thorium complexes each confirm the coordination modes. Further, these ligands were evaluated to check the extraction behavior with Am(III), U(VI), Th(IV), and Pu(IV) as a function of nitric acid concentration.
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