Session: Computational Science Applications in Nuclear & Radiochemistry:

Properties of pertechnic acid have been reported by Soderquist et al. [1]. They have proposed the existence of acidic species of H₂TcO₄⁺ and H₅TcO₆ for an aqueous solution of HTcO₄. In this study, these structures and their related structures have been analyzed within the DFT combined with Quantum Theory of Atoms in Molecules (QTAIM) [2]. The structures in gaseous and aqueous phases have been optimized employing nonempirical meta-GGA functional, TPSSTPSS [3].
The standard basis set, 6-31G(d,p), is used for the elements other than Tc. Stuttgart RSC 1997 together with its effective core potential (ECP) has been used for Tc. This basis set has been obtained from the EMSL basis set exchange library, https://bse.pnl.gov/bse/portal [4]. Gaussian 09 [5] has been used for the optimization and additional analyses of the optimized structures have been done by Multiwfn 3.8 dev [6]. The optimized structures of H₂TcO₄⁺ and HTcO₄ with Mulliken charges in an aqueous solution are given in Fig.1. In particular, O-H bonds covering acidic protons have been explored by analyzing their bond orders, dipole moments, real space functions relating to QTAIM. In general, higher Fuzzy Bond Order (FBO) values have been obtained for aqueous phases. The FBO values in ascending order were obtained as H₂TcO₄⁺ < H₅TcO₆ < HTcO₄ and species derived from H₅TcO₆ by releasing their protons. Other O-H bonding properties were analyzed as a function of structure and its position in the structure.

Zeki Buyukmumcu

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