The coordination polyhedra GaS n in crystal structures

Aspects of the topology of actinide atom substructures in crystal structures and the concept of antiliquid

“…For example, the number of structures of Ancontaining compounds (from Th to Cf) has risen by a factor of 2-4 in the last ten years in comparison with the data from Serezhkin, Verevkin et al (2008). Thus, it was interesting to check if the occurrence of VD polyhedra with 14 faces in Pa, Am, Cm, Bk and Cf substructures has risen in accordance with the forecast by Serezhkin, Verevkin et al (2008). As k A values for U-containing compounds vary in a very wide range from 1 to 128, it was also interesting to study the relation between (p, f) distributions and k A values.…”

“…In 2006-2008, using Voronoi-Dirichlet (VD) tessellation we conducted an extensive calculation for verification of the MSF principle for single-element substructures (A substructures) (Serezhkin et al, 2006a(Serezhkin et al, , 2009aSerezhkin, Vologzhanina et al, 2007;Serezhkin, Verevkin et al, 2008;. It is convenient that the number of faces (f) of VD polyhedra is equal to the KN of corresponding atoms in A substructures.…”

“…The increased prevalence of VD polyhedra with 14 faces was explained within the stereoatomic model of crystal structures (Serezhkin, 2007), in which atoms are regarded as 'soft' deformable spheres of constant volume (Serezhkin et al, 2006a(Serezhkin et al, , 2009aSerezhkin, Vologzhanina et al, 2007;Serezhkin, Verevkin et al, 2008;. Let us remind readers that to quantify the amount of free and filled space in a sphere packing, we use the packing coefficient which is called the density and which shows the proportion of the space that is occupied by the spheres (Conway & Sloane, 1999).…”

Uranyl Coordination Compounds with Alkaline Earth Metals and Crotonate Ligands

“…In that sense this work continues our studies to reveal the role of the secondary metals in the formation of bimetallic polynuclear units. [12,28,39,40] As was concluded in paper in ref., [39] Voronoi-Dirichlet (VD) tessellation with the method of intersecting spheres (MIS) [41,42] are the best for studying coordination environment of metals, as well as of atoms of all other chemical elements. According to the MIS, coordination numbers (CN) of M in the title compounds are equal to 6, 7 or 8 ( Table 3).…”

“…Thus, the VD polyhedra of both U atoms in Usubstructure of compound 1 which does not feature clustering have 14 faces and belong to a widespread CTT [4 4 5 4 6 6 ]-2, designating that these VD polyhedra have four quadrangular, four pentagonal and six hexagonal faces. [54,55] On the other hand, the VD polyhedra of U atoms in U-substructures of compounds 2-4 feature odd numbers of faces (13 or 15) and are very rare. [54] Especially VD polyhedra of U atoms in Usubstructures of compounds 3 and 4 are very complex, containing rare faces with 7 and 8 vertices and different CTT's for every independent U atom, what shows difficult to perceive packing of [UO 2 L 3 ]complexes in these structures.…”