Controlling the primary coordination sphere: Complexation of the 4f-elements by crown ethers as models for potential extraction systems
The lanthanides are hard Lewis acids, and as such exhibit a high affinity for hard Lewis bases, such as oxygen. This results in the formation of aquo species in aqueous solutions. To displace the coordinated water molecules, complexation of the lanthanides by crown ethers was investigated. In the reactions of hydrated lanthanide chlorides and nitrates with 12-crown-4, 15-crown-5, and 18-crown-6, several complexes have been isolated and structurally characterized: [M(OH[sub 2])[sub 5] (12-crown-4)]Cl[sub 3][center dot]2H[sub 2]O (M = Ce, Nd, Sm-Er), [MCl[sub 2](OH[sub 2])[sub 2](12-crown-4)]Cl (M = Ho-Lu), [YCl[sub 2](OH[sub 2])(OHMe)(12-crown-4)]Cl, [LaCl[sub 2](NO[sub 3])(12-crown-4)][sub 2], [La(NO[sub 3])(OH[sub 2])[sub 4](12-crown-4)]Cl[sub 2][center dot]CH[sub 3] CN, [MCl[sub 3] (15-crown-5)](M = La, Ce), [Er(OH[sub 2])[sub 8]]Cl[sub 3][center dot]15-crown-5, [CeCl[sub 2](OH[sub 2])(18-crown-6)]Cl[center dot]2H[sub 2]O, [MCl(OH[sub 2])[sub 2] (18-crown-6)]Cl[sub 2][center dot]2H[sub 2]O (M = Pr, Nd, Eu), [LCl[sub 2] (NO[sub 3])(18-crown-6)], [Pr(NO[sub 3])[sub 3] (18-crown-6)], and [M(NO[sub 3])[sub 3] (OH[sub 2])[sub 3]]18-crown-6 (M = Tb, Dy, Y, Ho, Er, Tm, Lu). In most cases, complexes where the crown ether is directly coordinated are observed, although hydrogen bonded complexes in which the crown ether is hydrogen bonded to water molecules which are directly coordinated to the metal center are not uncommon. Experiments on the extraction of Pu[sup 4+] in aqueous biphase systems were performed. The goals of the experiments were to become familiar with extraction chemistry and the chemistry of Pu[sup 4+] as an example of actinide behavior. The goals of this investigation were to learn to control the primary coordination sphere of the lanthanides to enhance their extraction and to extend the database of structures of the lanthanides with crown ethers.
- Research Organization:
- Northern Illinois Univ., De Kalb, IL (United States)
- OSTI ID:
- 7072295
- Country of Publication:
- United States
- Language:
- English
Similar Records
Primary to secondary sphere coordination of 18-crown-6 to lanthanide (III) nitrates: Structural analysis of [Pr(NO{sub 3}){sub 3}-(18-crown-6)] and [M(NO{sub 3}){sub 3}(OH{sub 2}){sub 3}]{center_dot}18-crown-6 (M = Y, Eu, Tb-Lu)
Synthesis and structural characterization of the monodentate 12-crown-4 and hexaethylene glycol complexes of uranium(VI): [UO[sub 2]Cl[sub 2](OH[sub 2])[sub 2](12-crown-4)][center dot]12-crown-4 and UO[sub 2]Cl[sub 2](OH[sub 2])[sub 2](hexaethylene glycol)
Related Subjects
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400105* -- Separation Procedures
400702 -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPLEXES
CHARGED PARTICLES
CHEMICAL REACTIONS
COMPLEXES
COORDINATION VALENCES
CROWN ETHERS
ETHERS
EXTRACTION
IONS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PLUTONIUM IONS
RARE EARTH COMPLEXES
SEPARATION PROCESSES
VALENCE