Coordination chemistry of two heavy metals: I, Ligand preferences in lead(II) complexation, toward the development of therapeutic agents for lead poisoning: II, Plutonium solubility and speciation relevant to the environment

Thesis/Dissertation · Mon Nov 01 04:00:00 EST 1993

DOI:https://doi.org/10.2172/10107977· OSTI ID:10107977

Neu, Mary Patricia ^[1]

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1. Univ. of California, Berkeley, CA (United States)

The coordination chemistry and solution behavior of the toxic ions lead(II) and plutonium(IV, V, VI) have been investigated. The ligand pK_as and ligand-lead(II) stability constants of one hydroxamic acid and four thiohydroaxamic acids were determined. Solution thermodynamic results indicate that thiohydroxamic acids are more acidic and slightly better lead chelators than hydroxamates, e.g., N-methylthioaceto-hydroxamic acid, pK_a = 5.94, logβ₁₂₀ = 10.92; acetohydroxamic acid, pK_a = 9.34, logβ₁₂₀ = 9.52. The syntheses of lead complexes of two bulky hydroxamate ligands are presented. The X-ray crystal structures show the lead hydroxamates are di-bridged dimers with irregular five-coordinate geometry about the metal atom and a stereochemically active lone pair of electrons. Molecular orbital calculations of a lead hydroxamate and a highly symmetric pseudo octahedral lead complex were performed. The thermodynamic stability of plutonium(IV) complexes of the siderophore, desferrioxamine B (DFO), and two octadentate derivatives of DFO were investigated using competition spectrophotometric titrations. The stability constant measured for the plutonium(IV) complex of DFO-methylterephthalamide is logβ₁₂₀ = 41.7. The solubility limited speciation of ²⁴²Pu as a function of time in near neutral carbonate solution was measured. Individual solutions of plutonium in a single oxidation state were added to individual solutions at pH = 6.0, T = 30.0, 1.93 mM dissolved carbonate, and sampled over intervals up to 150 days. Plutonium solubility was measured, and speciation was investigated using laser photoacoustic spectroscopy and chemical methods.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), CA (United States)
• Sponsoring Organization: USDOE; Seaborg (Glenn T.) Inst. for Transactinium Science
• DOE Contract Number: AC03-76SF00098; W-7405-ENG-48
• OSTI ID: 10107977
• Report Number(s): LBL--34872; ON: DE94004203
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400100
400201
ANALYTICAL AND SEPARATIONS CHEMISTRY
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
CHEMICAL PROPERTIES
DRUGS
EXPERIMENTAL DATA
HAZARDOUS MATERIALS
LEAD IONS
PHYSICAL PROPERTIES
PLUTONIUM IONS
PLUTONIUM OXIDES
SOLUBILITY