ELECTROCHEMISTRY OF BORON-CAPPED TC-99 DIOXIME COMPLEXES

Boron-capped technetium dioxime (BATO) compounds (1) have been studied by cyclic voltammetry, d.c. polarography, and controlled-potential co ulometry/bulk electrolysis in DMF. Chloro and bromo BATOs undergo an i rreversible two-electron reduction at mercury while for hydroxy BATOs two consecutive one-electron reductions are observed. Rhenium analogs to the BATOs exhibit qualitatively similar reduction behaviour, but at more negative potentials. The uncapped tris-dioxime complexes (2) als o show similar electrochemical behaviour. The two-electron peak potent ial is more sensitive to changes in the axial ligand and the dioxime t han to changes in substituents on the boronic acid capping group. BATO reduction apparently leads to axial ligand loss and yields an air-sen sitive, purple species. Both BATO reduction and oxidation appear to be biologically inaccessible.