Stereochemistry of Technetium in Halogen-Containing Compounds

Within the framework of the stereoatomic model of crystal structure, a crystal-chemical analysis of compounds containing coordination polyhedra of Tc(IV)Hal6 (Hal = F, Cl, Br, or I) and Tc(II)Br4 was carried out. A linear correlation was established between the solid angles of the faces of Voronoi–Dirichlet polyhedra corresponding to valence and non-valence Tc–Hal contacts and the corresponding internuclear distances. It was shown that technetium halide complexes form structural fragments in the form of isolated Tc(II)Br4 tetrahedra and isolated Tc(IV)Hal3 octahedra (Hal = F, Cl, Br, or I), as well as chains formed by edge-sharing Tc(IV)Hal6 octahedra, which can be described by three crystal-chemical formulas. In total, 35 structures containing Tc(IV)Hal6 (Hal = F, Cl, Br, or I) and Tc(II)Br4 fragments were found to be representable by thirteen topologically distinct types of 3-, 2-, and 1-periodic underlying nets.