Neodymium cations

A monomeric (and anhydrous) neodecanoate (= NDH) was obtained from the ligand exchange reaction between hydrated neodymium(III) acetate Nd(0Ac)3(H20)6 and neodecanoic acid (Scheme 14). The coordination sphere of the large neodymium cation is saturated by an additional molecule of neodecanoic acid, as evidenced by MALDI-TOF mass spec-... 

Scheme 24 Formation of a structurally characterized heterobimetallic Nd(III)/A1 complex from Nd(Oi-Pr)3 and alkylaluminum reagents. Three different types of metal environments are realized for six structurally independent neodymium cations Ndl-Nd6 [170]...

Nd2(H20)i4 Na(H20)P5W3oOiio ] shows a one-dimensional chain structure built from Preyssler anions [Na(H20)P5W3oOno] " linked by neodymium cations. In the complex, the adjacent [Na(H20)P5W3oOno] clusters are linked to each other about a center of symmetry... 

The electrochemical behaviour of LiCl-KCl eutectic+ LaCl3, CeCl3 and NdCl3 (0.5 wt%) with various concentrations of LiF was also evaluated. By differential pulsed voltammogram using tungsten electrode, the broad peak of electro-reduction which corresponds to the co-electrodeposition of all rare earths could be identified as well as a similar peak which corresponds to the electro-reduction into Nd ". Therefore, if the potential constant electrolysis can be performed at a potential close to reduction into Nd " ", this fact implies that it is possible to enrich the neodymium cation around the cathode. 

In contrast, the Ln(silox)3 system appears to be thermally rather inert and the neodymium derivative sublimes at around 340 °C with slight decomposition [16]. The strength of the Si-O bond and the unfavorable separation of silyl cations (route C) might explain this behavior [34]. Thermal stability of the silox ligand was also detected in Ba2(silox)4(THF) [314]. 

We think that the solid solution is produced by the simultaneous substitution of neodymium and lithium atoms for the strontium atoms of the cation lattice of... 

The ratio of the size of the metal ion and the radius of the internal cavity of the macrocyclic polyether determines the stoichiometry of these complexes. The stoichiometry of these complexes also depends on the coordinating ability of the anion associated with the lanthanide. For example, 12-crown-4 ether forms a bis complex with lanthanide perchlorate in acetonitrile while a 1 1 complex is formed when lanthanide nitrate is used in the synthesis [66]. Unusual stoichiometries of M L are observed when L = 12 crown-4 ether and M is lanthanide trifluoroacetate [67]. In the case of 18-crown-6 ligand and neodymium nitrate a 4 3 stoichiometry has been observed for M L. The composition of the complex [68] has been found to be two units of [Nd(18-crown-6)(N03)]2+ and [Nd(NCh)<--)]3. A similar situation is encountered [69] when L = 2.2.2 cryptand and one has [Eu(N03)5-H20]2- anions and [Eu(2.2.2)N03]+ cations. It is important to note that traces of moisture can lead to polynuclear macrocyclic complexes containing hydroxy lanthanide ions. Thus it is imperative that the synthesis of macrocyclic complexes be performed under anhydrous conditions. 

The only complexes of lanthanum or cerium to be described are [La(terpy)3][C104]3 175) and Ce(terpy)Cl3 H20 411). The lanthanum compound is a 1 3 electrolyte in MeCN or MeN02, and is almost certainly a nine-coordinate mononuclear species the structure of the cerium compound is not known with any certainty. A number of workers have reported hydrated 1 1 complexes of terpy with praseodymium chloride 376,411,438), and the complex PrCl3(terpy)-8H20 has been structurally characterized 376). The metal is in nine-coordinate monocapped square-antiprismatic [Pr(terpy)Cl(H20)5] cations (Fig. 24). Complexes with a 1 1 stoichiometry have also been described for neodymium 33, 409, 411, 413, 417), samarium 33, 411, 412), europium 33, 316, 411, 414, 417), gadolinium 33, 411), terbium 316, 410, 414), dysprosium 33, 410, 412), holmium 33, 410), erbium 33, 410, 417), thulium 410, 412), and ytterbium 410). The 1 2 stoichiometry has only been observed with the later lanthanides, europium 33, 411, 414), gadolinium, dysprosium, and erbium 33). 

The neodymium ion concentration in the organic phase was measured by back-extraction with 6M nitric acid, removal of the neodymium by adsorption with the cation exchange resin, Dowex 50 x 8, and titration of the neodymium-free aqueous phase with NaOH using phenolphtalein... 

Fundamental studies have been reported using the cationic liquid ion exchanger di(2-ethylhexyl) phosphoric acid in the extraction of uranium from wet-process phosphoric acid (H34), yttrium from nitric acid solution (Hll), nickel and zinc from a waste phsophate solution (P9), samarium, neodymium, and cerium from their chloride solutions (12), aluminum, cobalt, chromium, copper, iron, nickel, molybdenum, selenium, thorium, titanium, yttrium, and zinc (Lll), and in the formation of iron and rare earth di(2-ethylhexyl) phosphoric acid polymers (H12). Other cationic liquid ion exchangers that have been used include naphthenic acid, an inexpensive carboxylic acid to separate copper from nickel (F4), di-alkyl phosphate to recover vanadium from carnotite type uranium ores (M42), and tributyl phosphate to separate rare earths (B24). 

Praseodymium and neodymium built almost identical structures with myo-inositol. In the crystal structures of [Pr(myo-Ins)]Cl3 9 H2O [100] and [Nd(myo-Ins)]Cl3 9 H2O [101], by triva-lent lanthanide cations complexed myo-inositol, each Pr or Nb is coordinated to nine oxygen atoms, two from the inositol (two adjacent hydroxyl groups) and seven from water molecules... 

Separation of Actinides from the Samples of Irradiated Nuclear Fuels. For the purpose of chemical measurements of burnup and other parameters such as accumulation of transuranium nuclides in irradiated nuclear fuels, an ion-exchange method has been developed to separate systematically the transuranium elements and some fission products selected for burnup monitors (16) Anion exchange was used in hydrochloric acid media to separate the groups of uranium, of neptunium and plutonium, and of the transplutonium elements. Then, cation and anion exchange are combined and applied to each of those groups for further separation and purification. Uranium, neptunium, plutonium, americium and curium can be separated quantitatively and systematically from a spent fuel specimen, as well as cesium and neodymium fission products. 

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