Lanthanide, and yttrium metal ions

Solution and Solid State NMR Studies of Alginic Acid Binding with Alkaline Earth, Lanthanide, and Yttrium Metal Ions... 

By examining the effect of alkaline earth, lanthanide and yttrium metal ions on alginates, we can begin to understand how these metals interact with simple components of soil matter. After laying the groundwork with these studies, we can then predict possible mechanisms for ion transport in soils. 

Through our studies of alkaline earth, lanthanide, and yttrium ions, and their interaction with the polyuronide al c acid, we would like to predict the environmental behavior of the actinides. We chose to begin our study by investigating the interaction of soil constituents with the divalent alkaline earth metal ions and the trivalent lanthanides, which serve as convenient trivalent actinide analogs. Soil is primarily composed of polyelectrolytes. By choosing a simple polyelectrolyte such as the polyuronide alginic acid, we can begin to establish possible pathways of metal ion transport. 

Figure 2 Isocratic separation of standard mixture of 14 lanthanides and yttrium on a 250 mm x 4 mm column, packed with 5 pm silica IDA. Eluent 1.6x 10" moll" HNO3 with 0.5moll KNO3 flow rate 1.0 ml min " k column temperature 65°C, sample volume 20 pi, sample concentration of each metal was 4 ppm in 0.2% HNO3. Detection, Arsenazo III postcolumn reaction at 658 nm. (Reprinted with permission from Nesterenko PN and Jones P (1998) Isocratic separation of lanthanides and yttrium by high performance chelation ion chromatography. Journal of Chromatography A 804 223-231 Elsevier.)...

The lanthanides are congeners of the Group IIIA metals scandium and yttrium, with the +3 oxidation state usually being the most stable. These ions are strong oxyphilic Lewis acids and catalyze carbonyl addition reactions by a number of nucleophiles. Recent years have seen the development of synthetic procedures involving lanthanide metals, especially cerium.195 In the synthetic context, organocerium... 

L.M. Vallarino, IMacrocycle complexes of the lanthanide(III) yttrium(III) and dioxouranium(VI) ions from metal-templated syntheses 443... 

Both scandium and yttrium are electropositive metals with similar reduction potentials to the lanthanides ( °Sc +/Sc = -2.03 V ° Y +/Y = —2.37 V compare values of-2.37 V and -2.30 V for La and Lu, respectively). The ionic radii of Sc + and Y + are 0.745 A and 0.900 A, respectively (in six coordination). The former is much smaller than any Ln + ion but yttrium is very similar to Ho + (radius 0.901 A) purely on size grounds, it would be predicted that yttrium would resemble the later lanthanides but that scandium would exhibit considerable differences, and this expectation is largely borne out in practice. Table 7.1 lists stability constants for typical complexes of Sc + and Y +, together with values for La + andLu +. 

Attempts to synthesize the clathrochelate complexes of lanthanide ions via template condensation of the tripodal amine tren with formaldehyde bis-(dimethylamino)methane derivative on the rare-earth metal ion were successful only for ytterbium. The [Yb(metr)](CF3S03)3 AN clathrochelate was obtained in 3-5% yield [165]. With ytterbium cation, as well as with cerium, praseodymium, europium, yttrium, and lanthanum ions, the major reaction products proved to be mono- and dibridged semiclathrochelate complexes with ligands 1 and 2 (Scheme 71). 

For the trivalent lanthanides -and actinides, as well as for yttrium and scandium. the equilibrium constant for the extraction reaction has been shown to vary inversely with the ionic radius of the metal ion. It has therefore been concluded that the extracted complexes are all of the M(HA2)3 type, involving predominantly ionic metal—ligand bonds. The similarity of the IR spectra of the scandium(III) and thorium(IV) complexes of D2EHPA to those of the alkali metals is also indicative of the importance of ionic bonding. ... 

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