Racemization of tris chelate complexes

Among the commonest types of diketo complex are those with the stoichiometries M(diketo)3 and M(diketo)2. The former all have structures based on an octahedral disposition of the six oxygen atoms. The tris-chelate molecules then actually have D3 symmetry and exist as enantiomers. In cases where there are unsymmetrical diketo ligands (i.e., those with R R") geometrical isomers also exist, as indicated in (21-XXVIII). Such compounds have been of value in investigations of the mechanism of racemization of tris-chelate complexes, which are discussed in detail in Section 21-17. 

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