Neodymium polymers

A common feature of catalysts based on 4 and 5f block elements is that of being able to polymerize both butadiene and isoprene to highly cistactic polymers, independently of the ligands involved. Butadiene, in particular, can reach a cistacticity as high as 99% with uranium based catalysts (3) and cistacticity of > 98% with neodymium based catalysts (4). This high tacticity does not change with the ligand nature (Fig. 1) in contrast to conventional catalysts based on 3-d block elements. A second feature of f-block catalysts is that the cis content of polymer is scarcely... 

Teranishi, T., Nakata, K., Miyake, M., and Toshima, N., Promition effect of polymer-immobilized neodymium ions on catalytic activity of ultra fine palladium particles, Chem. Lett., 277, 1996. 

Si02-supported neodymium-based catalyst mixtures Nd(naph)3/Al2Et3Cl3/ A1( Bu)3 (54) and Al( Bu)2H (DIBAH), instead of Al( Bu)3, were also tested as initiators for the gas-phase polymerization of 1,3-butadiene by varying the polymerization temperature, nature and feed of co-catalyst and polymerization time (Table 12.8). High ds-1,4-contents (97.8-98.9%) and activities between 400 and 2300 kg-PBD molNd h bar were observed, but the polymers displayed broad molecular weight distributions of 2 < M /M < 8 [158-160]. 

Vermonden T, van Steenbergen MJ, Besseling NAM, Marcehs ATM, Hennink WE, Sudholter EJR, Stuart MAC. Linear rheology of water-soluble reversible neodymium(III) coordination polymers. J Am Chem Soc 2004 126 15802-15808. 

A catalyst system composed of neodymium chloride/trialkyl aluminium is presumed to give living polymer of butadiene containing cis-1,4 units higher than 98%. This living... 

By application of the dimethylsilyl-bridged bisfluorenyl neodymium chloride complex [Me2Si(Ci3H8)2]NdCl (cocatalysts Buli, DIBAH, BuMgCl, BuMgOct) a complete new class of polymers is accessible by the copolymerization of ethylene and BD [307]. By reaction of 1 eq. BD and 2 eq. of ethylene 1,2-cyclohexane units are formed along the polymer chain. More than half of the inserted BD units (53-58 mol %) are involved in the ring closure reaction. The residual non-cyclicized BD units exhibit a nearly identical ratio of trans-1,4- and 1,2-units. 

Fig. 16 Neodymium glutarate, a coordination polymer containing chains of edge-sharing NdOj polyhedra.52 Gray spheres denote carbon, red oxygen, and white hydrogen, with NdOs polyhedra in blue. Reproduced with permission. Copyright 1998, Royal Society of Chemistry.

Butadiene has been converted into poly-l,4-(cis-butadiene) in greater than 98.3% by Ziegler-Natta catalysis comprising neodymium versatate, diethyl aluminum chloride, diisobutylaluminum hydride, and triisobutyMuminum. The polymer was then converted into a polybutadiene-polyurethane copolymer by reacting with a diisocyanate and diol. This copolymer exhibited low cold flow and high affinity for silica or carbon black, excellent elasticity, and abrasion resistance. 

Hydrates of rare earth chlorides also have two different crystal systems a triclinic system for lanthanum, cerium, and praseodymium, as well as a monoclinic system for neodymium to lutetium and yttrium. CeCl3-7H20, as an example of the former system, is different from the above infinite polymer as two cerium atoms are connected by two [i2-bridges to form a dimer. The formula for this dimer is [(H20)7Ce([i2-Cl)2Ce(H20)7]Cl4 as shown in Figure 1.18. Therefore, the coordination number of cerium is nine and the polyhedron takes on a destroyed mono-capped square antiprism configuration. 

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). 

For a neodymium(III)-Pc with the formula [Pc2Nd] H a new hydrogen bonded polymer structure in the crystal solid state is proposed ... 

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