Crystal structures of molecular adducts between uranyl nitrate and 2,2′:6′,2"-terpyridine or 2,2′-bipyridyl

Complexes of uranyl nitrate with aromatic molecular ligands : [UO(2)Terpy(NO3)(2)] and (H(2)Terpy)(2)[UO2(NO3)(2)(H2O)(2)](NO3)(4) . 4H(2)O (Terpy 2,2':6',2"-terpyridine), (Hbipy)[UO2(NO3)(3)] and [(UO2)(2)(Bipy)(2)O-2(NO3)(2)] (Bipy-2,2'-bipyridyl) and (HPy)(4)[(UO2)(2)(NO3)(4)(OH)(2)](NO3)(2) (Py-pyridine) were characterized by X-ray diffraction analysis. In all these compounds, the U(VI) atom has the hexagonal bipyramidal environment. The U-O bond lengths in the UO22+ have close values. In the equatorial planes, the U-N bond lengths with the Bipy and Terpy ligands are identical, whereas the U-O bond lengths depend on the type of the ligand. The lengths of the equatorial bonds increase in the sequence U-N > U-O-nitr > U-O-hydr > U-O-perox. The geometric characteristics of the coordinated and solvate Terpy and Bipy molecules are different. The lengths of the N-O bonds in the NO3- groups depend on the participation of the O atom in the coordination of the central atom, the coordination mode, and the formation of hydrogen bonds.