Dawson metalates

Dawson, Metal-metal and metal-semiconductor composite nanoclusters. Colloids and Surfaces A. Physicochemical and Engineering Aspects 2002, 202, 269-279. 

Allen GC, Warren KD (1974) The Electronic Spectra of the Hexafluoro Complexes of the Second and Third Transition Series. 19 105-165 Alonso JA, Baibas LC (1993) Hardness of Metallic Clusters. 80 229-258 Alonso JA, Baibas LC (1987) Simple Density Functional Theory of the Electronegativity and Other Related Properties of Atoms and Ions. 66 41-78 Andersson LA, Dawson JH (1991) EXAFS Spectroscopy of Heme-Containing Oxygenases and Peroxidases. 74 1-40 Antanaitis BC, see Doi K (1988) 70 1-26... 

Dawson, D.A., E.F. Stebber, S.L. Burks, and J.A. Bantle. 1988. Evaluation of the developmental toxicity of metal-contaminated sediments using short-term fathead minnow and frog embryo-larval assays. Environ. Toxicol. Chem. 1 27-34. 

Dawson, H.M. McCrae, J. "LIV.-Metal-Ammonia Compounds in Aqueous Solution. Part II. The Absorptive Powers of Dilute Solutions of Salts of the Alkali Metals," J. Chem. Soc. Trans., 1901, 79 > 493-511. 

G.R. Dawson, C.F. Winsper, and D.H. Sansome, A complete appraisal of oscillatory metal working, Journal of Metal Working, Aug./Sept. 1970, Part 1, 234-238, Part 11, 254-261. 

Petrogenesis of dykes related to Cu-Au base-metal Au-Ag occurrences, Mt. Freegold area, Dawson Range, Yukon Territory,... 

Mortensen, J.K., Appel, V., Hart, J.R. 2003. Geological and U-Pb constraints on base and precious metal vein systems In the Mount Nansen area, eastern Dawson Range, Yukon. Yukon Exploration and Geology 2002, 165-174. 

Bineli-Betsi, T. Lentz, D.R. 2009. Petrogenesis of dykes related to Cu-Au base-metal-Au-Ag occurrences, Mt. Freegold area, Dawson Range, Yukon Territory, Canada. Extended conference abstract, 24 lAGS meeting, Fredericton, NB, Canada. 

The possibilities of POMs compositions and structures are virtually enormous, and the number of these molecules actually prepared and characterized continues to grow unabated. However, examination of their short electrochemical studies, which are becoming a usual part of their characterization, shows that a limited selection of representative groups of POMs is sufficient for a description of the main electrochemical behaviors of this class of chemicals. Therefore, a-Keggin- and Dawson-type heteropolyanions of phosphotungstate, silicotungstate, phosphomolybdate, and silicomolybdate mixed addenda heteropolyanions, and transition-metal substituted heteropolyanions including sandwich-type derivatives were selected for the present article. 

The formation of sandwich-type POMs from solutions of metal cations and triva-cant heteropolytungstate species may alternatively be viewed as means to sequester cations from solution [116]. The question then arises if reversible dissociation of the metal cations from the multidentate ligands is possible as well. The sequestration and subsequent release of metal cations under appropriate conditions is of considerable interest in waste decontamination technology as well as in medicine [124]. Following these ideas, the demetallation process of ten multi-iron Wells-Dawson polyoxometalates is studied by cyclic... 

In conclusion, it was shown that the experimental evidence for an initial electron transfer site in an equatorial position ( l) of the unsubstituted Dawson-type P2Wi8062 heteropolyanion can be rationalized by the belt -centered character of the LUMO. The change of the reduction site (o a2) upon substitution in the cap region (0-2 site) by a more electronegative metal center (Mo for instance) is also consistent with the localization of the LUMO on the substituted center(s). 

Dawson EB, Evans DR, Nosovitch J (1999) Third-trimester amniotic fluid metal levels associated with preeclampsia. Arch Environ Health, 54 412-415. 

According to F. C. Franklin and C. A. Kraus,40 liquid ammonia readily dissolves sodium and potassium iodides. The partial press, of ammonia in soln. of potassium iodide at 25°, as measured by R. Abegg and H. Riesenfeld, is raised from 13 45 mm. of water to 13 28, and 14 88 mm. for 0 5W-, N-, and l 5Ar-soln. respectively. H. M. Dawson and J. McCrae have shown that the distribution of ammonia between water and chloroform is generally lowered by the addition of various salts of the alkali metals and ammonium which they tried—halides, nitrates, chlorates, oxalates, sulphates, carbonates, hydroxides this means that the solvent power of aq. soln. of the alkali salts is in general less than that of pure water—lithium chloride, ammonium bromide, and sodium iodide act in the opposite way. The other halide salts of lithium were not tried. The change produced in the partition coeff. by the halides, at 20°, is as follows ... 

The synthesis and characterization of isolated, isomerically pure a2-[P2W17061(Mn+ L)]y- (Mn+ = Mn3 +, Fe3+, Co2+, Ni2+, and Cu2+) as aqueous-soluble potassium salts (L = HzO) and as the more novel, organic-solvent-soluble tetrabutylammonium salts (L = Br) are described herein. These preparations yield mono-metal-substituted complexes of the Dawson 2 isomer, 2-[P2Wi7O6i]10, that are typically >98% free of the (Xi isomer.1,2 The X-ray crystallographic structures of the a2-[P2W17O61]10 lacunary precursor and the a2-[P2W17061(Co" OH2)]8- complex are known.3... 

The electrochemistry of heteropolymolybdates parallels that of the tungstates but with the following differences the reduction potentials are more positive and the primed species (metal-metal bonded ) are much less stable. Scheme 7 applies for or-fSiMo O ]4-. Species in parentheses are detectable only by rapid scan cyclic voltammetry, and XVIII decomposes rapidly at 0°C. The reduced anions such as II and IV are easily obtained by controlled potential electrolysis or by careful chemical reduction, e.g. with ascorbate. The use of metal ion reductants generally leads to other reactions, (equation 7). The reduced anions slowly isomerize (equation 8). The isomerization can be followed polarographically (all S potentials are more positive) or by NMR spectroscopy. By this means / isomers of most Keggin and Dawson molybdates have been prepared. 

Studies with sulfated zirconia also show similar fast catalyst deactivation in the alkylation of isobutane with butenes. It was found, however, that original activities were easily restored by thermal treatment under air without the loss of selectivity to trimethylpentanes. Promoting metals such as Fe, Mn, and Pt did not have a marked effect on the reaction.362,363 Heteropoly acids supported on various oxides have the same characteristics as sulfated zirconia.364 Wells-Dawson heteropoly acids supported on silica show high selectivity for the formation of trimethylpentanes and can be regenerated with 03 at low temperature (125°C).365... 

H. M. Dawson and J. McCrae, D. P. Konowaloff, and W. Gaus also used soln. of various salts of the alkali metals, and of potassium, sodium, cupric, or barium hydroxide in place of water and also copper sulphate, copper chloride, zinc sulphate, and cadmium iodide while M. 8. Sherrill and D. E. Russ examined the effect of ammonium chromate. W. Herz and A. Kurzer examined the distribution of ammonia between water and a mixture of amyl alcohol and chloroform. Observations on the distribution of ammonia between water and chloroform were made by T. S. Moore and T. F. Winmill, G. A. Abbott and W. C. Bray, and J. M. Bell. J. H. Hildebrand gave for the molar fraction N X104 of ammonia at 1 atm. press., and 25°, dissolved by ethyl alcohol, 2300 methyl alcohol, 2730 and water, 3300. 

Lacunary spedes can act as structural motifs with numerous metal cations, leading to mono-, di- and trinuclear transition-metal-substituted POMs according to the number of vacant sites. The metal incorporation involves the reaction of aquated first-row and occasionally second-row d-block metal ions, M(H20)6z +, with a lacunary POM derived from the Keggin, Wells-Dawson and other POM families. In addition, lacunary spedes assemble into large POM structures, either directly or with incorporation of metal ion linkers. 

Mantoura, R.F.C., 1982. Organo-metallic interactions in natural waters. In E.K. Duursma and R. Dawson (eds). Marine organic chemistry Elsevier, Amsterdam, pp. 179-223. 

Dawson A., Kamat P.V. (2001) Semiconductor-metal Nanocomposites. Photoinduced Fusion and Photocatalysis of Gold-Capped Ti02 (Ti02/Gold) Nanoparticles, J. Phys. Chem. B. 105(5), 960-966. 

The preparation of TMSPs (Keggin-type and Dawson-type) is described in detail by Walker and Hill [73] and Lyon et al. [74]. The tetrakis(tetra-n-butylammo-nium) salt of PM011O39, (/i-BvuN HjPMohOjs (1) is prepared and metalated to form the corresponding Keggin-type TMSP. 

Dawson J, Ghiotto F, McMaster J, Schroder M. Metal complex of hydrogenase active sites. In Wydrzynski TJ, Hillier W, editors. Molecular solar fuels. Cambridge, UK The Royal Society of Chemistry 2012. p. 326-86. 

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