Crystal structure of 2,2'-bipyridine complexes of Np(V) and Pu(V)m-nitrobenzoates

摘要

Single crystals of [AnO_2(bipy)(OOCC_6H_4NO_2)-(H_2O)]·0.5bipy (An=Np, Pu, bipy=2,2'-bipyridine) have been synthesized and their structures have been determined by X-ray analysis. The compounds are isomorphous and contain electroneutral complexes [AnO_2(bipy)(OOCC_6H_4NO_2)(H_2O)] and solvate bipy molecules. Actinide atoms in both compounds are seven coordinated. Actinide contraction results in a shortening of all bonds in the coordination spheres at the transition from Np to Pu. The structures are compared with those of other An(V) benzoate compounds. In contrast to earlier structurally characterized An(V) benzoates, cation–cation interaction in [AnO_2(bipy)(OOCC_6H_4NO_2)(H_2O)] complexes is absent. Lower complexing ability of m-nitrobenzoate is compensated by engagement of water molecule into the coordination sphere of An(V). This is accompanied by formation of strong H-bonds between AnO_2~+ cations and coordinated water molecules.