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
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
ACTINIDE COMPLEXES
EXTRACTION
CROWN ETHERS
CHEMICAL REACTIONS
RARE EARTH COMPLEXES
COORDINATION VALENCES
PLUTONIUM IONS
CHARGED PARTICLES
COMPLEXES
ETHERS
IONS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
SEPARATION PROCESSES
VALENCE
400105* - Separation Procedures
400702 - Radiochemistry & Nuclear Chemistry- Properties of Radioactive Materials