AnSen (an = Th, U, Np, Pu, Am, or Cm) Coordination Polyhedra in Crystal Structures

Voronoi–Dirichlet (VD) polyhedra are used to analyze the structures of compounds that contain coordination polyhedra AnTen (An = Th, U, Np, Pu, Am, or Cm) in their crystal structures. It is found that tellurides contain An(III), An(IV), and U(V) atoms that coordinate 6 to 9 tellurium atoms. The described VD polyhedra of An and Te atoms demonstrate the possibility of using data on crystal structure to estimate the multiplicity of Te–Te bonds and the formal charge on tellurium atoms. The most important characteristics of homoatomic structural moieties (including linear and zig-zag chains formed by tellurium atoms) are discussed. It is shown that the formal charge (−1, −1.25, or −1.5) of tellurium atoms in linear chains is predetermined by the proportion of Te− to Te2− ions arranged statistically along the chain axis. It is established that all tellurides built from zig-zag chains of tellurium atoms contain U(V) atoms.