Darstellung und Struktur von Ln3TiO4Cl5(Ln = La − Nd) - die ersten Oxochlorotitanate der Seltenen Erden

Preparation and Crystal Structure of Ln₃TiO₄Cl₅ (Ln = La?Nd) – the First Oxochlortitanates of Rare Earth The compounds Ln₃TiO₄Cl₅ have been prepared by reaction of LnCl₃/LnOCl/TiO₂ (1:2:1) (Ln = La?Nd) in evacuated silica ampoules. Single crystals of La₃TiO₄Cl₅ were obtained by chemical transport reaction (T₂ → T₁; T₂ = 1050°C, T₁ = 950°C) using chlorine (p(Cl₂; 298 K) = 1 atm) and sulfur as transport agents with La₂TiO₅ as starting material. La₃TiO₄Cl₅ crystallizes in the orthorhombic space group Pnma (No. 62) with cell-dimensions a = 16.760(2) Å, b = 4.0991(6) Å, c = 14.634(2) Å, Z = 4. The structure was refined to give R = 4.76%, R_w = 2.47%. Main building units are TiO₅ trigonal bipyramides and threefold capped trigonal prisms around La. The relationship to La₂TaO₄Cl₃ will be discussed.