X-ray photoelectron spectroscopy of potential technetium-based organ imaging agents

Technetium-99 3d binding energies were measured for a set of 12 compounds which included model species and several potential radiopharmaceuticals. The range of compounds from the free metal to the technetium(VII) valence state gave a span of 4.9 eV. Anionic and coordinated halogen was distinguished in the chlorine 2p and bromine 3d spectra of a number of phosphine complexes. Similar spectra of two dioxime complexes indicated significantly more electron density on the halogen than is the case for a coordinated species. The result is indicative of weakening of the metal-chlorine bond. Analogous spectra were obtained when bromine was substituted for chlorine. The boron 1s binding energy for boronic acid present in the dioxime complexes was in agreement with the proposed oxygen population on the boron atom.