Crystal and molecular structure of (C10H10N2)Np(NO3)6·2H2O compound. Stereoisomerism of neptunium (4) hexanitrate complex

Crystal structure of the compound, mentioned in the title was determined (autodiffractometer CAD4 SDP). Lattice parameters: a=1.5610(2), b=1.0190(1), c=1.4799(2)nm; sp.gr.Pna21, Z=4, ρcalc=2.28g/cm3, R=0.0258, Rω=0.0334. Basic structural elements are presented by (Np(NO3)6)2- complex anions, 2.2'-dipyridyl cations and crystallization water molecules. The anion is formed by six nitrate ions, coordinated to the central Np(4) ion in a bidentate way. The mean Np-O distance is 0.2505(7)nm, coordination Np polyhedron is distorted icosahedron. Eigensymmetry of D3 anion, location of nitrate ions in it differ from the known hexanitrate Np, Th, Ce complexes with Th symmetry. Existence of complex neptunium(4) nitrate with dipyridyl of different compositions is explained by the fact, that stereoisomers of Np(4) hexanitrate complex, contained in this compounds and possessing D3 and Th symmetry respectively, are characterized by sufficiently different distances between external (not coordinated to Np) oxygen atoms of nitrate ions