The isotope Tc-99 (beta(max), 293.7; half-life, 2.1 x 10(5) years) is an abundant product of uranium-235 fission in nuclear reactors and is present throughout the radioactive waste stored in underground tanks at the Hanford and Savannah River sites. Understanding and controlling the extensive redox chemistry of Tc-99 is important in identifying tunable strategies to separate Tc-99 from spent fuel and from waste tanks and, once separated, to identify and develop an appropriately stable waste form for Tc-99. Polyoxometalates (POMs), nanometer-sized models for metal oxide solid-state materials, are used in this study to provide a molecular level understanding of the speciation and redox chemistry of incorporated Tc-99. In this study, Tc-99 complexes of the (alpha(2)-P2W17O61)(10-) and (alpha(1)-P2W17O61)(10-) isomers were prepared. Ethylene glycol was used as a "transfer ligand" to minimize the formation of TcO2 center dot xH(2)O. The solution structures, formulations, and purity of (TcO)-O-V(alpha(1)/alpha(2)-P2W17O61)(7-) were determined by multinuclear NMR. X-ray absorption spectroscopy of the complexes is in agreement with the formulation and structures determined from P-31 and W-183 NMR. Preliminary electrochemistry results are consistent with the EXAFS results, showing a facile reduction of the (TcO)-O-V(alpha(1)-P2W17O61)(7-) species compared to the (TcO)-O-V(alpha(2)-P2W17O61)(7-) analog. The alpha(1) defect is unique in that a basic oxygen atom is positioned toward the alpha(1) site, and the (TcO)-O-V center appears to form a dative metal-metal bond with a framework W site. These attributes may lead to the assistance of protonation events that facilitate reduction. Electrochemistry comparison shows that the Rev analogs are about 200 mV more difficult to reduce in accordance with periodic trends.