Uranyl dicarboxylate polymers

A second method of solving the kinetics dilemna consists of driving a polymerization reaction to completion by removing a volatile coproduct as in the case of uranyl dicarboxylate polymers from uranyl acetate and the dicarboxylic acid (5) ... 

NMR measurements also provide information on the coordination of the ligands in the uranyl polymers. Solid-state I c-NMR confirms the coordination modes of the carboxylate ligands to the uranyl ion that is, both monodentate and bidentate carboxylate coordination modes are evident. The uranyl dicarboxyl ate polymers which possess two moles of coordinated DMSO exhibit two carbon-13 carbonyl resonances, one at about 175 ppm downfield from tetramethylsilane (TMS) and one at about 185 ppm. The polymers which possess only one mole of coordinated DMSO exhibit only the carbonyl peak near 185 ppm. Based on other known coordination compounds, the 175 ppm peak can be assigned to monodentate carboxylate and the 185 ppm peak to bidentate carboxylate. Thus, 7-coordination predominates in the polymers with either one or two moles of solvent coordinated to the uranyl ion, which is consistent with the infrared results reported elsewhere (5). 

Table 2. Uranyl coordination polymers constructed from dicarboxylate linkages...

A further note concerns the rapidity of precipitate formation. Precipitation was believed to be the molecular weight limiting factor for the condensation of the uranyl ion with dicarboxylic acid salts. Since precipitation is so rapid, it is possible that precipitation of the polymer is the limiting factor for uranyl uptake for the present system. 

Carraher and coworkers have reported that the removal of toxic metal ions from water can be achieved by polychelation of dicarboxylic acids (2) to uranyl ions, (3) resulting in the production of coordination polymers such as 4 (Scheme 1). This... 

---