Vanadium complexes citrates

Kaliva, M., T. Giannadaki, A. Salifoglou, C.P. Raptopoulou, and A. Terzis. 2002. A new dinuclear vanadium(V)-citrate complex from aqueous solutions. Synthetic, structural, spectroscopic and pH-dependent studies in relevance to aqueous vanadium(V)-citrate speciation. Inorg. Chem. 41 3850-3858. 

Kaliva M, Raptopoulou CP, Terzis A, Salifoglou A (2003) Systematic studies on pH-dependent transformations of dinuclear vanadium(V)-citrate complexes in aqueous solutions. A perspective relevance to aqueous vanadium(V)-citrate speciation. J Inorg Biochem 93 161-173... 

Tsaramyrsi M, Kaliva M, Salifoglou A, Raptopoulou CR Terzis A, Tangoulis VGiaprinizakis J (2001) Vanadium(lV)—citrate complex interconversions in aqueous solutions. A pH-de-pendent synthetic, structural, spectroscopic, and magnetic study. Inoig Chem 40 5772-5779... 

Unisulf [Unocal sulfur removal] A process for removing sulfur compounds from petroleum fractions, similar to the Stretford process, but including in the catalytic solution vanadium, a thiocyanate, a carboxylate (usually citrate), and an aromatic sulfonate complexing agent. Developed by the Union Oil Company of California in 1979, commercialized in 1985, and operated in three commercial plants in 1989. 

Iron is transported in forms in which it is tightly complexed to small chelators called siderophores (microorganisms) or to proteins called transferrins (animals) or to citrate or mugeneic acid (plants). The problem of how the iron is released in a controlled fashion is largely unresolved. The process of mineral formation, called biomineralization, is a subject of active investigation. Vanadium and molybdenum are transported as stable anions. Zinc and copper appear to be transported loosely associated with peptides or proteins (plants) and possibly mugeneic acid in plants. Much remains to be learned about the biological transport of nonferrous metal ions. 

Tetravalent vanadium forms a large number of complexes, all of which involve the vanadyl group, VO, and most of which are ato- complexes. The most common oxalato complex is H2(V0)2(C204)3, which can give a positive test for the presence of the oxalate ion in aqueous solutions. Aqueous solutions of the pure monovanadyl complex do not test for the presence of the oxalate ion. Complexes of sulfate and sulfite analogous to the oxalate complexes have been observed [4]. Ducret [5] suggested the existence of weak fluoro complexes at a pH of approximately 3. A tartrate and two citrate complexes can also be formed with the vanadyl ion. 

Kaliva M, Kyriakakis E, Gabriel C, Raptopoulou CP, Tarzis A, Tuchangues JP, Salifoglou A (2006) Synthesis isolation, spectroscopic and structural characterization of a new pH complex structural variant from the aqueous vanadium(V)-peroxy-citrate ternary system. Inorg Chim Acta 359 4535 548... 

Kaliva M, Kyriakakis E, Salifoglou A (2002) Reactivity investigation of dinuclear vanadium(lV, V)-citrate complexes in aqueous solutions. A closer look into aqueous vanadium-citrate interconversions. Inorg Chem 41 7015-7023... 

Zhou ZH, Zhang H, Jiang YQ, Lin DH, Wan HL, Tsai KR (1999) Complexation between vanadium(V) and citrate spectroscopic and structural characterization of a dinuclear vanadium(V) complex. Transit Met Chem 24 605-609... 

Ammonium hydroxide precipitates uranium quantitatively at pH 4 or greater.- The presence of ammonium salts and macerated filter paper facilitate precipitation. Separation Is made from alkali metals, alkaline earths, and cations forming ammonia complexes. Repeated precipitations may be necessary to give sufficient separation. Phosphorus, vanadium, silicon, boron, aluminum. Iron and other elements of the ammonium hydroxide analytical group also are precipitated. Complexlng agents carbonate, oxalate, citrate, tartrate, fluoride, etc.. Interfere. 

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