Neodymium occurrence

The known structures of the lanthanide and actinide metals are indicated in table 5.01, from which it will be seen that the structures characteristic of the true metals, and particularly the hexagonal close-packed arrangement, are common. Polymorphism, however, is of frequent occurrence among these elements, and plutonium, for example, crystallizes in no fewer than six modifications—the A1 and A2 structures indicated and four others of greater complexity. Praseodymium, neodymium and samarium are of interest in that they possess close-packed structures in which the sequence of layers is... 

Keeping in mind the efficiency of aluminum derivatives as cocatalysts and CTA when associated to lanthanide versatate in conjugated diene polymerization, we investigated the behavior of some Nd-carboxylate-based MOF/aluminoxane catalysts versus isoprene polymerization [33]. At elevated temperatures, the value of initiation efficiency (vs neodymium) appeared far higher than 100%, which suggests the probable occurrence of transfer reactions between Nd and A1 during the polymerization process. It is worth noting that the CM-selectivity remains close to 80% (Scheme 27.7). 

Apparently, a significant decrease in the neodymium chloride particle size in the first 4-5 h of the synthesis is not due to the occurrence of the complexation on the particle surface (contracting sphere model), because the yield of the complex in this period is low. Most probably, a decrease in the particle size of the initial NdCl3 is associated with disintegration of the solid phase under the action of mechanical stirring, with the wedging effect produced by solvent molecules solvating the particle surface. This... 

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