Comprehensive Solid-State NMR Characterization of Electronic Structure in Ditechnetium Heptoxide
journal contributionposted on 29.09.2010, 00:00 by Herman Cho, Wibe A. de Jong, Alfred P. Sattelberger, Frédéric Poineau, Kenneth R. Czerwinski
A relativistic density functional theory description of the electronic structure of Tc2O7 has been evaluated by comparison with solid-state 99Tc and 17O NMR spectroscopic data (the former isotope is a weak β 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 the surrounding atoms. The magnitudes of the predicted tensor principal values appear to be uniformly larger than those observed experimentally, but the discrepancies were within the accuracy of the approximation methods used. The convergence of the 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 in condensed phases.