The chemistry of technetium: Toward improved diagnostic agents.

Within the last five years significant advances have been made in elucidating the chemistry of technetium. While this element is continually produced in some abundance during the operation of fission nuclear reactors, its practical application has been limited to nuclear medicine. Owing to the development of the "technetium generator" almost two decades ago, 99mTc is now the preferred isotope for many diagnostic studies involving the imaging of internal organs by radioscintigraphic techniques; however, many of the agents employed have yet to be well characterized from a chemical standpoint. Owing to its position in the middle of the periodic table, the chemistry of this element has already proven rich, even when limited to aqueous solution. Subtle chemical differences often control the relative stabilities of the various oxidation states and each oxidation state exhibits more than one geometry. Coordination complexes involving Tc(III), Tc(IV) and Tc(V) tend to predominate in preparations used for diagnosis. Recent synthetic advances now pave the way for new series of technetium compounds with well-described chemistry. Of these, methods for coordinating chelating nitrogen ligands to Tc(V) offer substantial versatility. (This review covers the literature through August, 1981.) [ABSTRACT FROM AUTHOR]