Crystal structures of the penta- and hexa-hydrate of thulium nitrate.

ABSTRACT

Tm(NO3)3·5H2O and Tm(NO3)3·6H2O, or more precisely [Tm(NO3)3(H2O)4]·H2O and [Tm(NO3)3(H2O)4]·2H2O, respectively, have been obtained from a concentrated solution of Tm2O3 in HNO3. The crystal structures of the two hydrates show strong similarities as both crystallize in space group P with all atoms at general positions and contain neutral, mol-ecular [Tm(NO3)3(H2O)4] complexes, i.e. ten-coordinated TmIII cations with three nitrate anions as bidentate ligands and four coordinating water mol-ecules, and one or two additional crystal water mol-ecules, respectively. All building units are connected by medium-strong to weak O-H⋯O hydrogen bonds. Tm(NO3)3·6H2O represents the maximally hydrated thulium nitrate as well as the heaviest rare earth nitrate hexa-hydrate known to date.