Crystal structure and spectral properties of complexes of tetravalent Th, U, Np and Pu nitrates with trimethyl phosphate and dimethyl phosphate

Abstract

Abstract Single crystals of [Th(TMP)6(NO3)2][Th(TMP)2(NO3)5]2 (1), [Th(TMP)4(NO3)3][Th(TMP)2(NO3)5] (2), [U(DMP)3(NO3)] (3), [Np(DMP)3(NO3)] (4), and [Pu(DMP)2(NO3)2(H2O)]·H2O (5) have been synthesized and their structures have been determined by X-ray analysis. IR and optical spectra of polycrystalline compounds 3 and 4 were measured at room temperature. The Th(IV) is crystallized as two complexes with TMP molecular ligands and NO3 anions in coordination environment. The Th atoms in cationic moieties of 1 and 2 are characterized by coordination number of 10 and in the anionic moieties by coordination number of 12. Compounds of U(IV), Np(IV) and Pu(IV) were obtained with two different anions (NO3 and DMP) in coordination environment of the central atom. U(IV) and Np(IV) compounds are isostructural and the main motif of structure is made of infinite chains of [An(DMP)3(NO3)] n , twisted around hexagonal axes. In the structure of Pu(IV) the main structural motif is made of infinite chains [Pu(DMP)2(NO3)2(H2O)] n , extending along the b axis. The coordination numbers of An(IV) are equal to 8 for U and Np, and 9 for Pu. The difference in the structure and composition of formed compounds Th and U, Np, Pu could be explained by hydrolysis of TMP at the synthesis conditions.