SUBJECTS neodymium

A 250-ml reaction vessel was used as the polymerization reactor. Each polymerization reaction was carried out either under static conditions in a freezer, where the container was placed in a bath of glycol, or dynamically, by subjecting the container to agitation in a tank of glycol. Isoprene monomer having a purity of 99.2% was used. All polymerizations were conducted in 10-g containers and cyclohexane at 15°C with a solvent/monomer mass ratio of 9. In a typical polymerization the neodymium catalyst/diethyl aluminium chloride base varied from 150 to 500 pmol per 100 g of isoprene. 

Dipicolinates (pyridine-2,6-dicarboxylates) have been investigated in some detail with structures determined for several tris complexes such as Na3[Nd(dipic)3]-15H20 and Na3[Yb(dipic)3]13H20, typical of the early and later lanthanides, respectively. The lanthanides have essentially tricapped trigonal prismatic coordination geometries, isostruc-tural along the lanthanide series they have been the subject of important solution NMR studies. Mono and bis complexes can also be synthesized the mono complex [Nd(dipic)(H20)4] CIO4 has a polymeric structure in which each picolinate is bound to three different (nine-coordinate) neodymium ions. 

The abundant crust that was produced in the 1.9-1.7 Ga interval has been the subject of numerous studies, and the evolution of that work illustrates important elements in study of the continental crust. Following the demonstration of a juvenile origin for the —1.8 Ga crustal assemblage in Colorado (DePaolo, 1981), there followed a period in which neodymium isotopic data were gathered for numerous terrains in the northern continents (Figure 4). In North America, studies by Nelson and DePaolo (1984, 1985), Bennett and DePaolo (1987),... 

In a typical sample of pottery, the corrections to the chromium for neodymium, tantalum, and iron interferences were 0.9%, 0.2%, and 0.6%, respectively. For obsidian, in which chromium is very low, the respective corrections were 12.6%, 6.2%, and 17.2%. Because the corrections themselves are subject to a significant error, chromium is not a useful element for fingerprinting obsidians. 

Copolymerization of styrene and conjugated dienes is another attractive subject which provides the most commonly used styrene-butadiene rubbers (SBRs). Boisson reported that by using neodymium amide Nd N(SrMe3)2 3 and TIBA and DEAC, SBRs with 10-15 mol% of styrene were produced [189], although drops in both activity and molecular weight were observed as compared with those of... 

The phenylacetylides were obtained from the metathesis of NaC CPh with the respective chloro complex (3a)2LnCl in THE in 77% (La) and 66% (Yb) yield. ° The alkyl complexes (3a)2Nd(CH2SiMe3) and (3a)2Nd[CH(SiMe3)2] were formed almost quantitatively from (3a)2NdCl and the respective alkyllithium reagent in toluene or benzene solution the alkoxo species (3a)2Nd(OCHMe2) and (3a)2Nd(OCH-f-Bu2) have been obtained from the reaction of (3a)2Nd-(BHEts) with acetone and pivalone, respectively. Of all the neodymium compounds just described only (3a)2NdOCH-f-Bu2 has been isolated in pure form (71% yield) and subjected to the standard methods of characterization. 

Meggers 1942) and that of element 61 is obtained by interpolation consequently, these are subject to some doubt. The ground states given for neodymium (Schuurmans 1946), samarium, europium and gadolinium are those spectroscopically determined (Meggers 1942) for the neutral atoms and should be considered as well established. 

Phase relationships as a function of pressure Jayaraman et al. (1966) investigated pressure-induced transformations in several intra rare earth alloy systems and included the Sm-type Nd-50at% Gd alloy. Equal molar amounts of neodymium and gadolinium metals were arc-melted in an argon atmosphere, then heat treated at 500° C for several days in sealed evacuated quartz tubes. X-ray patterns established that this alloy had the Sm-type structure under equilibrium conditions. After this alloy had been subjected to 4.0 GPa pressure at 450°C for 5 hr, the pressure was related and the temperature was reduced to ambient. X-ray patterns revealed that the alloy had transformed to dhep structure that was retained metastably after the release of pressure. 

The shape of the curve shown in Figure 56 predicts a fairly high stability of neodymium and promethium dichlorides among the compounds with CN = 9 and dysprosium and thulium dichlorides among the compounds with CN = 7, that is, exactly those lanthanide dichlorides that (except PmCl2) not only were successfully synthesized but also were the subject of some physicochemical measurements that required heating to high temperatures. For instance, saturated vapor pressure of... 

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