ELECTRONIC AND STRUCTURAL INVESTIGATIONS OF TECHNETIUM COMPOUNDS BY X-RAY-ABSORPTION SPECTROSCOPY

X-ray absorption near edge structure spectroscopy has been used to est ablish the chemical shifts of the technetium K edge ina range of compo unds containing Tc in a variety of formal oxidation states. The edge p ositions span 19.9 eV from Tc metal to NH4TcO4. Strong correlation bet ween chemical shift and formal oxidation state is observed. Extended X -ray absorption fine structure (EXAFS) spectroscopy of Tc-2(CO)(10) in dicates that multiple scattering along the Tc-C-vector is more importa nt than direct Tc..O scattering. TcO2 is shown by EXAFS to possess a d istorted rutile structure with a closest Tc-Tc distance of 2.61 Angstr om. This is rationalized in terms of the Goodenough model for bonding in transition metal dioxides.