Technetium nitrogen ligand complexes

The reliable prediction of redox potentials as a function of composition is useful in the synthetic design and application of technetium and other transition metal complexes. A parametric procedure for doing so on the basis of ligand additivity principles has been developed by Lever [28]. Lu etal. [29] used this scheme to correlateTc / ",Tc "/ , andTc hi potentials with the composition of octahedral technetium complexes containing halide, nitrogen, and phosphorus donor ligands. The results are illustrated in Fig. 2 [29], where the observed potentials are plotted according to... 

Dinitrogen, Phosphine, Phosphite, and Related Complexes Complexes with Nitrogen Ligands Nitrosyl and Thionitrosyl Complexes Technetium(II)... 

Complexes with Dioximes, Schiff Bases, and Other Nitrogen Ligands Complexes with Monodentate Phosphines and Related Ligands Complexes with Bidentate Phosphine, Arsine, and Related Ligands Complexes with Sulfur Ligands Nitrosyl and Thionitrosyl Complexes VII. Technetium(IV)... 

Tc(IV), the DTPA ligand is undoubtedly coordinated in a hexadentate fashion about the Tc through three nitrogens and three carboxylate oxygens, leaving two uncoordinated carboxylates. Deutsch and Packard [56], however, observed three uncoordinated carboxylates on the complex by titration with base, suggesting that the technetium may be in the 4- 5 oxidation state. If Tc(V) is correct, then a 6-coordinate complex would be present with a carboxylate in the position trans to the Tc = 0 group. 

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