PNNL

Abstract

A relativistic density functional description of the electronic structure of Tc2O7 has been evaluated by comparison with solid state 99Tc and 17O NMR spectroscopic data (the former isotope a weak beta-emitter). Every site in the molecule can be populated by a nucleus with favorable NMR characteristics, providing the rare opportunity to obtain a comprehensive set of chemical shift and electric field gradient tensors for a small molecular transition metal oxide. NMR parameters were computed for the central molecule of a (Tc2O7)17 cluster, using standard ZORA optimized all-electron QZ4P basis sets for the central molecule and DZ basis sets for surrounding atoms. The magnitudes of the predicted tensor principal values appear to be uniformly larger than observed experimentally, but discrepancies were within the accuracy of the approximation methods used. The convergence of calculated and measured NMR data suggests that the theoretical analysis has validity for the quantitative understanding of structural, magnetic, and chemical properties of Tc(VII) oxides. The William R. Wiley Environmental Molecular Sciences Laboratory is a U.S. Department of Energy (DOE) national scientific user facility located at Pacific Northwest National Laboratory (PNNL) in Richland, Washington. The Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.