Glycolate ligands

Figure 1. Entropy of formation of the monoligand complex as a function of the atomic number of the lanthanides for EDTA, fluoride, acetate, and glycolate ligands...

In addition to the structures displayed in Fig. 2.13, other possibilities also exist as depicted by Crans etal. in the case of oxovanadium 1,2-diolates. It has also been pointed out that the structural differences of the glycol ligands result in very different geometries and demonstrate subtle factors affecting the coordination chemistry of snch systems. These studies substantiate the very fine balance between coordination geometries and the respective glycolate ligands in their metal complexes. 

In each case, and solution NMR studies indicated the presence of two isomers [11] the aminebis(imido) complex 4 and the imidobis(amido) complex 5. The ratio of 4/5 depends on the glycolate ligand. The more electron-withdrawing perfluoropinacolate (PFP) ligand favors structure... 

The control of the equilibrium between 4 and by the electronic nature of the glycolate ligands is relevant to the fundamental question of the influence of support acidity on the catalyst behavior in ammoxidation. 

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