Nd2(OH)2(CrO4)2 and [Tb2(CrO4)3(H2O)5].2H2O

Crystal Structures of the Europium and Yttrium Hydroxychromates Eu(OH)(CrO4) and Y(OH)(CrO4); Structural Evolution as a Function of the Ln3+ Ionic Radius

“…Each europium atom is bridged to sixteen other europium atoms either by chromate groups or by hydroxyl oxygen atoms with distances ranging from 3.732(8) Å to 7.522(8) Å. Europium and chromium polyhedra form pentagonal and tetragonal channels parallel to the a direction; hydrogen atoms lie in the first type ) are surrounded by four and five oxygen atoms respectively with distances shorter than 3.0 Å. The number of oxygen atoms around the hydroxyl groups in Ln(OH)(CrO 4 ) (Ln = Nd, Gd, Tb, Er and Yb)[8][9][10][11] increases with the atomic number of the lanthanide, ranging up to eight oxygen atoms in the Yb(OH)(CrO 4 ) structure[11].To confirm the coordination number of lanthanide and yttrium ions equal to eight, BVS Yttrium ion was also presented on this figure in order to compare with the family of lanthanides. In this case, it is reasonable to consider a same CN for all lanthanide and yttrium ions.…”