ИСТИНА

Pertechnetate and perrenate ions are now readily available from the 99Mo/99mTc and 188W/188Re generators and its applications are interesting in nuclear medicine for diagnostic and therapeutic applications [1]. In recent years, neutral hosts of a complex structure with internal cavities containing nitrogenous bases have been developed [2]. In case of effective binding with perrhenate anions and pertechnetate, they can be promising suppliers of rhenium or technetium to cells of various organs and tissues. Purine nitrogen heterocyclic molecules are important elementary molecular components in modeling the creation of similar hosts for ReO4- or TcO4-. These data also may also serve for elaboration or improving the Tc and Re separation methods. Two new perrhenates and two new pertechnetates with adenine and guanine cations (isothermal evaporation of solutions of magnesium perrhenate and nitrogenous bases in HCl) were synthesized as single crystals in this study. An X-ray diffraction study was performed (automatic diffractometer Bruker KAPPA APEX II). Crystallographic data for perrhenates: H2Gua(ReO4)2 (I): a = 5.2014(2), b = 15.7463(6), c = 14.9004(5) Å, β = 92.908(2) о, at 100 К, Z = 4, space gr. P21/n, R1 = 0.0199; H2Aden(ReO4)2 (II): a = 16.0078(8), b = 5.0950(2), c = 16.2841(9) Å, β = 116.078(2) о, at 100 К, Z = 4, space gr. P21/c, R1 = 0.0176. Crystallographic data for pertechnetates: HGua(TcO4) (III): a = 5.4073(2), b = 7.2230(3), c = 12.5344(5) Å, α = 106.129(2) β = 91.945(2), γ = 104.688(2)о, at 100 К, Z = 2, sp. gr. P-1, R1 = 0.019; HAden(TcO4) (IV): a = 9.2587(3), b = 9.3129(3), c = 20.7470(6) Å, α = 77.576(1), β = 85.838(1), γ = 89.554(1)о, at 100 К, Z = 8, sp. gr. P-1, R1 = 0.0347. In both perrhenate compounds, the nitrogenous base molecules are twice protonated. All nitrogen atoms are protonated in I, and the nitrogen atom in the para-position to the amino group is not protonated in II. The NH and NH2 groups in both compounds are proton donors in hydrogen bonds, and the oxygen atoms of perrhenate ions act as proton acceptors. One bond between the amino group and the perrenate ions in structure I is bifurcate. The oxygen atom of the guaninium cation in structure I does not participate in hydrogen bonds. In structure I, each cation is linked by hydrogen bonds with six anions, and in II - with four. The crystal packing in structures I and II can be represented as consisting of cationic and anionic columns. In both structures, each cationic column is surrounded by 6 anionic ones and each anionic one is surrounded by 3 cationic ones. In both structures, there is no π-stacking interaction. The study showed that the similar nature of cations and the similar composition of compounds lead to the formation of crystalline packings of the same type, despite some differences in the system of hydrogen bonds. In both pertechnetate compounds, the nitrogenous base molecules are protonated one time. The crystal packing in structures III and IV can be represented as consisting of cationic and anionic columns. In both structures, each cationic column is surrounded by 1 anionic and each anionic one is surrounded by 1 cationic. References [1] W. A. Volkert and T. J. Hoffman, Chem. Rev., 1999, 99, 2269. [2] A. Ravi, A. S. Oshchepkov, K. E. German, G. A. Kirakosyan, A. V. Safonov, V. N. Khrustalev, E. A. Kataev, Chemical Communications. 2018, 54(38), 4826.