Technetium complexes citrates

Moenze R (1977) Formation of technetium(III) citrate complexes. Radioehem Radioanal Lett 30 117-122... 

The need to achieve high yield in one-pot synthesis, coupled to the relative kinetic inertness of rhenium complex (e.g. compared to technetium) and the mild conditions required has led to the development of useful versatile rhenium(V) intermediates that can be quickly prepared in quantitative yield, and are metastable, i.e. kinetically labile enough to react rapidly with the final chelator, again in high yield. The most widely used ligands suitable for this purpose are polydentate hydroxycarboxylic acids such as glucoheptonate [116a], citrate (47), tartrate (48), and 2-hydroxyisobutyric acid (49) [159]. Examples are discussed elsewhere in this chapter. They are typically used in the presence of Sn(II) to reduce Re(VII) to Re(V), at moderately elevated temperature (50-100 °C) at pH 2-3 (acid pH promotes reduction of perrhenate, presumably by facilitat-... 

A catalyst might be a ligand, which rapidly forms an intermediary coordination complex such as gluconate, DTPA, and citrate (Davison 1983). Ligand exchange is applied when complex formation with a certain ligand is slow relative to formation of reduced, hydrolized technetium, resulting in a poor radiochemical yield. 

Ponto JA, Swanson DP, Freitas JE (1987) Clinical manifestations of radio-pharmaceutical formulation problems. In Hladik WB III, Saha GB, Study KT (eds) Essentials of nuclear medicine science. Williams Wilkins, Baltimore, pp 271-274 Porter WC, Dees SM, Freitas JE, Dworkin HJ (1983) Acid-citrate-dextrose compared with heparin in the preparation of in vivo/in vitro technetium-99m red blood cells. J Nucl Med 24 383-387 Russell CD, Cash AG (1979) Complexes of technetium with pyrophosphate, etidronate, and medro-nate. J Nucl Med 20 532-537... 

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