Interaction of Transuranium Elements with Biologically Important Molecules: Structural and Spectroscopic Study of Np(V) Complexes with Imidazole

New Np(V) complexes with imidazole, [NpO2(CH3COO)(Im)2(H2O)], [(NpO2)2(C2O4)(Im)6]·5Im·H2O, and [NpO2(NO2)(Im)4], were synthesized. Their crystal structures were determined using X-ray single-crystal diffractometry. The crystal structures are confirmed by IR and UV−vis spectroscopic data. In all three complexes, neptunium coordinates the imidazole molecule through the nitrogen atom. These complexes are the first example of direct bonding of the imidazole molecule to the actinide atom. These results suggest that coordination of histidine residue in proteins or other imidazole-containing biologically important molecules could occur under usual biological conditions.