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; <b>LnTeSO-1</b>), Ho₃(TeO₃)₂(SO₄)₂(OH)­(H₂O) (<b>LnTeSO-2</b>), Ln₂TeO₃(SO₄)₂(H₂O)₂ (Ln = Dy, Ho, Er; <b>LnTeSO-3</b>), Ln₂(Te₂O₅)­(SO₄)₂ (Ln = Er, Tm, Yb, Lu; <b>LnTeSO-4</b>), and Ln₂(Te₄O₁₀)­(SO₄) (Ln = Gd, Dy, Ho, Er, Tm, Yb; <b>LnTeSO-5</b>), have been prepared and characterized. The topologies of <b>LnTeSO-1</b>, <b>LnTeSO-2</b>, <b>LnTeSO-3</b>, <b>LnTeSO-4</b>, and <b>LnTeSO-5</b> 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 (<b>LnTeSO-1</b>) to chains (<b>LnTeSO-2</b>) to tetramers (<b>LnTeSO-3</b>) and finally to a monomer (<b>LnTeSO-4</b>). The coordination numbers of lanthanides decrease from nine (<b>LnTeSO-1</b>) to eight (<b>LnTeSO-2</b> and <b>LnTeSO-3</b>) to seven and six (<b>LnTeSO-4</b>). 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 <b>LnTeSO-1</b>.