Sequestering agent chemical structures

Chloride complexation studies of the actinide ions An3+, An4+, An02, and AnO + (An = U, Np, Pu) were reported in several comprehensive reviews [293-295], More recent investigations on aqua and chloro complexes of U02+, NpOz+, Np4+, Pu3+, etc., by x-ray absorption fine structure spectroscopy (XAFS) were reported [296,297]. In particular, it was established for U(IV) and Th(IV) aqua ions and fluoride complexes that both M(IV) aqua ions are 10-coordinate with M — O bond distances for U(IV) and Th(IV) of 2.42 0.01 A and 2.45 0.01 A, respectively [297], Physical and chemical studies of uranium aqueous complexes are reported [298,299a], A series of articles is dedicated to specific sequestering agents for the actinides [299b-e],... 

As described in an earlier section, transport problems posed by the six elements listed in the heading are somewhat simpler (with the exception of chromium) than those for iron. One very interesting recent development has been the characterization of sequestering agents produced by plants which complex a number of metal ions, not just ferric ions. A key compound, now well-characterized, is mugeneic acid (Figure 1.17)." The structural and chemical similari-... 

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