Diketonate complexes exchange

In closing, recovery of technetium from waste solution should be touched upon. Studies of the base hydrolysis of technetium P-diketone complexes revealed that all of the complexes studied decompose in an alkaline solution even at room temperature, until technetium is finally oxidized to pertechnetate. These phenomena are very important for the management of technetium in waste solutions. Since most metal ions precipitate in alkaline solution, only technetium and some amphoteric metal ions can be present in the filtrate [29]. A further favorable property of pertechnetate is its high distribution coefficient to anion exchangers. Consequently, it is possible to concentrate and separate technetium with anion exchangers from a large volume of waste solution this is especially effective using an alkaline solution [54],... 

Upon dissolution in an organic solvent, the /J-diketone complex forms an adduct with Lewis base B with weak interaction. The Lewis base molecule which is weakly bound enters into rapid exchange between the lanthanide site and bulk solution. Hence the observed LIS values in the NMR spectrum of Lewis base depend upon the equilibrium constants and the geometries of the acid-base complexes formed. 

Hydrolysis (the reverse of the preparative reaction) and other exchange reactions of the metal /3-diketonates have been studied in some detail in order to probe the mechanisms of inorganic substitution reactions. As mentioned in Section 4.1, there has been intense study of the intramolecular rearrangements of M(dike)3 complexes. Decomposition of metal /1-diketonate complexes to give high-purity metals or metal oxides is of technological importance. 

Co-crystallization of a mixture of [Y(hfa)3] and [Cu(acac)2] affords [Y(hfa)3(H20)2Cu(acac)2] (hfa = hexafluoroacetylacetonate) in which the individual metal diketonate complexes are linked by hydrogen bonds. Heating in vacuum induces ligand exchange and the liberation of gaseous [Cu(hfa)2]. Structures of heterodinuclear complexes show lanthanide-copper distances of approximately 3.2A and some tetrahedral distortion around copper. There is a small ferromagnetic interaction between the lanthanide and copper ions (/=0.8cm ). " ... 

Neutral diketone complexes are not generally available and so it is of interest to find Mg(C104)2 2acacH 2H20. The keto form of the Ugand has been shown to predominate in the complex in solution, by use of H NMR, and althou exchange between free and complexed ligand is fast, the keto-enol tautomerization is slow. ... 

Table 11 Kinetic Data for Methyl or r-Butyl Group Exchange in ZF (9-Diketonate Complexes ...

Another reaction shown to lead to active catalysts is the combination of (DAB)Ni(COD) with MAO under reaction conditions.although there is some indication that oxygen promotes this activity. - The use of /3-diketonate complexes of nickel as catalyst precursors leads to a halide-free system, and the MAO is proposed to participate in the ligand-exchange process. The order of mixing is important addition of MAO to a solution of Ni(acac)2 and DAB yields an active system, while addition of Ni(acac)2 to a solution of DAB/MAO is far less active. In addition, other routes to in situ catalyst formation have been reported. 

Both six- and five-coordinate species are involved in jS-diketone exchange reactions of manganese(III)-chloride-j3-diketone complexes. Kinetic data have been obtained in dichloromethane solution the starting complex contains five-coordinate manganese in this solvent, but six-coordinate in donor solvents. 

Similar luminescence enhancement was also observed by Yang et al. when ionic liquid 1 was added to the luminescence nanohybrid (Eu (TTA ) Lap) composed of Eu(in)-p-diketonate complexes and the synthesized clay, Laponite, dispersed in water (Fig. 7.14) [67]. The addition of 1 to the nanohybrid in water leads to a pronotmced increase in luminescence efficiency, and the absolute quantum yield of the modified nanohybrid is of 0.7, a high value that is rarely seen for luminescent nanohybrid in water. The mechanism is that the removal of the abundant protons on the Laponite platelets through a mechanism of synergic effect of ion exchange and neutralization drives the formation of Eu -p-diketonate complexes with high coordination number (Fig. 7.14). Abtmdant acidic sites exist on the surface of the... 

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