Electrochemical one‐electron reduction of dioxomolybdenum complexes with tetradentate N2O2 or N2S2 ligands containing sec. amino groups result in deprotonation of the amino groups and loss of an oxo ligand as H2O. This biomimetically undesirable result is circumvented by synthesis of the ligand (VI) and its complexes (VIII) (which can be prepared also from dioxobis(acetylacetonato)molybdenum and (VI) with 80% yield) and (X).
Outstation, Hamburg, FRG) for measuring the EXAFS spectra.Registry No. [L4Fe4(M-0)2(M-OH)4]I4-3H20, 123567-48-6; [L4Fe4-(µ-0)2(µ-0 )4]( 04)4•3 20, 123567-50-0; [L2Fe2(acac)2^-0)]-(C104)2, 118486-84-3; LFeClj, 86823-88-3. Supplementary Material Available; Tables of complete crystallographic data, bond distances and angles, and thermal parameters (5 pages); a listing of structure factor amplitudes (43 pages). Ordering information is given on any current masthead page.
T he USDO E has initiated an imp act assessme nt of existing vadose w oe conta m inatio n at th e Hanford Site SX tank farm in so ut heastern Washin gton State. The assessm ent followed th e Resource Co nserva tion and Recovery Act (Re RA) Corrective Action process (0 address the imp acts of past tan k waste releases (0 the vadose w oe a t the single-shell tank farm. Numerical model s were develop ed th at co ns ide r the extent of co nta m ina tio n prese n tly within the vadose w ile and pre d ict contami nant movement through the vadose w oe to groundwater. The transport of representative mobile (technetium-99) and immobile (ccsium-137) cons tituents was evaluate d in modelin g. The mod el considered the accelerated movement of moistu re aro un d a nd beneath single-shell tanks that is attributed to bare. gravelsurfaces resulting from the construction of the underground storage tanks. Infiltration. possibly nearing 100 mm yr-I , is further amplified in the tank farm becauseof me umbrella effect created by percolating moisture being diverted by the impermeable, sloping surface of the large. 24-m-diameter. buried tank domes. For both the base case (no-action alternative) simulation and a simulation mat considered placement of an interim surface barrier to minimize infiltration. predicted. groundwater concentrations for technerium-99 at the SX tank farm boundary were exceedingly high. on the order of 10 6 pei L-I . The predicted concentrations are, however. somewhat conservativebecause of our use of two-dimensional modeling for a three-dimensional problem. A seriesof simulations were performed, using recharge rates of 50.30, and 10 mm yr-t , and compared to the basecase (100 mm yr-I ) results. M expected.doweringmeteoric recharge delayed peak arrival times and reduced peak concentrations at the rank fann boundary.
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