Dimensional and coordination number reductions in a large family of lanthanide tellurite sulfates.

Twenty-two new lanthanide tellurite sulfates with five distinct structures, Ln2(Te2O5)(SO4)2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb; LnTeSO-1), Ho3(TeO3)2(SO4)2(OH)(H2O) (LnTeSO-2), Ln2TeO3(SO4)2(H2O)2 (Ln = Dy, Ho, Er; LnTeSO-3), Ln2(Te2O5)(SO4)2 (Ln = Er, Tm, Yb, Lu; LnTeSO-4), and Ln2(Te4O10)(SO4) (Ln = Gd, Dy, Ho, Er, Tm, Yb; LnTeSO-5), have been prepared and characterized. The topologies of LnTeSO-1, LnTeSO-2, LnTeSO-3, LnTeSO-4, and LnTeSO-5 are substantially different with respect to the connectivity between Ln polyhedra and the coordination environments of the lanthanide ions. For the first four topologies, the dimensionality changes from layered (LnTeSO-1) to chains (LnTeSO-2) to tetramers (LnTeSO-3) and finally to a monomer (LnTeSO-4). The coordination numbers of lanthanides decrease from nine (LnTeSO-1) to eight (LnTeSO-2 and LnTeSO-3) to seven and six (LnTeSO-4). We attribute the transitions to a decrease in the ionic radii of the 4f ions. Magnetic susceptibility measurements reveal no evidence for long-range magnetic ordering in these materials. However, diverse short-range magnetic correlations were observed within LnTeSO-1.