Copper beta-diketonate complexes

The Cu(tod)2 is much more soluble in hexane than almost all previously reported copper beta-diketonates.3 The logarithm of the partition coefficient of Cu(tod)2 between 1-octanol and water (log Poe,) is 3.64 0.20. This value, which is unusually large for a metal complex, is an indication of the expected bioavailability9 of [Cu(tod)2]. We have shown that a 50% (v/v) solution of H(tod) in kerosene is capable of extracting copper(II) ion from ammoniacal aqueous solutions in high yield, which may be useful for commercial recovery of copper from ore leachates.5... 

Triphenylformazan behaves as a bidentate ligand forming 2 1 complexes (217) with divalent copper, nickel, and cobalt.377 Formazan metal complexes can be compared to complexes of azo dyes or beta diketones due to structural similarity.301,302 In general, formazan metal complexes have low stability toward acids. However, when electron-donating substituents are added to the aromatic ring, a considerable enhancement in stability is observed. Cationic complexes of type 218 are also known. The complexation of formazan with metal cation can be accompanied by oxidation to the tetrazolium salt and the formation of a complex... 

The crude H(tod) is purified first by vacuum distillation (1 torr, 60-90°) to separate the ligand from high boiling but organic-soluble impurities. Second, the copper complex is synthesized, as described below, to isolate the beta-diketone from any by-products that are formed by self-condensation of the ketone. Crude [Cu(tod)2] (20 g) is placed in a 250-mL separatory funnel with 30 mL of hexane and 150 mL of 10% (1 M) aqueous sulfuric acid. The mixture is shaken until no blue color remains in the organic phase. The organic solution is isolated and the solvent is removed by rotary evaporation. Generally, the H(tod) product is 97-99% pure. 

The effect of the size of the metal beta-diketonate on the surface density is not as clear on silica as it is on alumina [9,35]. For instance, the number of metal atoms bound on 820 °C silica from Cu(thd>2, La(thd)3 and Ce(thd)4 is 0.5, 0.7 and 0.5/nm2, respectively. The difference in the number of La and Ce atoms can be explained by the size of the surface complexes to which two and three intact thd ligands are bound, respectively. In the case of copper the number of atoms would have been close to l/nm if the size of the surface complex having one intact ligand had been the dominating factor. The much smaller value suggests that the activation energy needed for the reaction to occur with all sterically available bonding sites was not exceeded at the reaction temperature of 170 °C used. Since... 

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