Lanthanide anion

The heteroatoms listed in Table 10 form complexes of stoichiometry [XWi0O36]8-. The structure, based on determinations of the CeIV and UIV anions, can be regarded as the attachment of two quadridentate ligands, derived from W6Oi9 through the loss of one W06 octahedron, to the heteroatom (Figure 18). The site symmetry of the latter is approximately D4d. The XW10 anions are of only moderate stability in aqueous solution (pH5.5-8.5). Electronic, vibrational and 170 NMR spectra have been recorded. The emission spectra and luminescence properties of several of the lanthanide anions have been discussed.84... 

C-H Bond activation, with lanthanides Ethylene polymerization, with lanthanides Zeigler-Natta catalyst, lanthanide Diene polymerization, with lanthanides Olefin polymerization, with lanthanides Butadiene polymerization, with lanthanides Isoprene polymerization, with lanthanides Anionic propagation, at lanthanides Living polymers, at lanthanides Pseudo-living polymers, at lanthanides Reaction orders, diene polymerization Active sites, diene polymerization... 

Lu W-G, Jiang L, Feng X-L et al (2009) Three-dimensimial lanthanide anionic metal—organic frameworks with tunable luminescent proptnties induced by cation exchange. Inorg Chem 48 6997-6999... 

Ion-exchange separations can also be made by the use of a polymer with exchangeable anions in this case, the lanthanide or actinide elements must be initially present as complex ions (11,12). The anion-exchange resins Dowex-1 (a copolymer of styrene and divinylben2ene with quaternary ammonium groups) and Amherlite IRA-400 (a quaternary ammonium polystyrene) have been used successfully. The order of elution is often the reverse of that from cationic-exchange resins. 

Many of the binary compounds of the lanthanides, such as oxides, nitrides, and carbides, can exist as non stoichiometric compounds. These form crystals where some of the anions ate missing from the sites the anions normally occupy. 

Therefore the extent of extraction or back-extraction is governed by the concentration of X ia the aqueous phase, the distribution coefficients, and selectivities depending on the anion. In nitrate solutions, the distribution coefficient decreases as the atomic number of the REE increases, whereas ia thiocyanate solutions, the distribution coefficient roughly increases as the atomic number of the REE increases. The position of yttrium in the lanthanide series is not the same in nitrate and thiocyanate solutions, and this phenomenon has been used for high purity yttrium manufacture in the past. A combination of extraction by carboxyUc acids then by ammonium salts is also utilized for production of high purity yttrium. 

Carbon monoxide [630-08-0] (qv), CO, the most important 7T-acceptor ligand, forms a host of neutral, anionic, and cationic transition-metal complexes. There is at least one known type of carbonyl derivative for every transition metal, as well as evidence supporting the existence of the carbonyls of some lanthanides (qv) and actinides (1) (see AcTINIDES AND THANSACTINIDES COORDINATION COMPOUNDS). 

In general the lanthanides, including cerium, have a low toxicity rating (17), especially when they are present in material having low aqueous solubiUty. When orally adrninistered poor absorption from the gastrointestinal tract tends to result in the lanthanides generally having Httle effect. The anion is often an important deterrninant in toxicity. 

C-type, related to the fluorite strueture but with one-quarter of the anions removed in sueh a way as to reduee the metal eoordination number from 8 to 6 (but not oetahedral) favoured by the middle and heavy lanthanides. 

The separation of basic precipitates of hydrous Th02 from the lanthanides in monazite sands has been outlined in Fig. 30.1 (p. 1230). These precipitates may then be dissolved in nitric acid and the thorium extracted into tributyl phosphate, (Bu"0)3PO, diluted with kerosene. In the case of Canadian production, the uranium ores are leached with sulfuric acid and the anionic sulfato complex of U preferentially absorbed onto an anion exchange resin. The Th is separated from Fe, A1 and other metals in the liquor by solvent extraction. 

PEO is found to be an ideal solvent for alkali-metal, alkaline-earth metal, transition-metal, lanthanide, and rare-earth metal cations. Its solvating properties parallel those of water, since water and ethers have very similar donicites and polarizabilities. Unlike water, ethers are unable to solvate the anion, which consequently plays an important role in polyether polymer-electrolyte formation. 

Bancroft and Gesser [870] conclude that kinetic factors are predominant in determining whether decomposition of a metal bromate yields residual bromide or oxide. The thermal stabilities of the lanthanide bromates [877] and iodates [877,878] decrease with increase in cationic charge density, presumably as a consequence of increased anionic polarization. Other reports in the literature concern the reactions of bromates of Ag, Ni and Zn [870] and iodates of Cd, Co, Mn, Hg, Zn [871], Co and Ni [872], Ag [864], Cu [867], Fe [879], Pb [880] andTl [874]. 

Aminopyridinato ligands form a special class of anionic ligands in which an aromatic ring is part of an amidinate system. These ligands have frequently been employed in early transition metal and lanthanide coordination chemistry. Their diverse and interesting chemistry has been described in detail by Kempe et al. ° and will thus be covered here only briefly. Typical reaction pathways leading to titanium aminopyridinato complexes are outlined in Scheme 169. Metathetical as well as salt-free routes have been developed. 

The coordination chemistry of ancillary amidinate ligands with a pyridine functionality has been described. Magnesium, aluminum, zirconium, and lanthanum complexes have been prepared in which the amidinate anions act as tridentate, six-electron-donor ligands Amidinate ligands containing quinolyl substituents were constructed in the coordination sphere of lanthanide... 

A remarkable variety of compounds in the Ca-(B,C,N) system has opened a window for research in related fields. With the elements boron, carbon and nitrogen, substance classes such as borocarbides, boronitrides, and carbonitrides can be considered to contain anionic derivatives of binary compounds B4C, BN, and C3N4. Until now, most compounds in these substance classes have been considered to contain alkali, alkaline-earth, or lanthanide elements. Lanthanide borocarbides are known from the work of Bauer [1]. Lanthanide boronitrides represent a younger family of compounds, also assigned as nitridoborates [2] following the nomenclature of oxoborates. 

---