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.