Mixed Valence Tungsten(IV,V) Compounds with Layered Structures (Part II)): Synthesis and Crystal Structures of Cu1−x[W2O2Cl6] and Cu1−x[W4O4Cl10

Abstract

AbstractThe reaction of CuCl with WOCl3 at 400 °C leads to a mixture of Cu1−x[W2O2Cl6] (1) and Cu1−x[W4O4Cl10] (2) in form of black lustrous needles. Both compounds crystallize in space group C2/m with a = 12.7832(5) Å, b = 3.7656(2) Å, c = 10.7362(3) Å, β = 119.169(2)° for 1 and a = 12.8367(19) Å, b = 3.7715(7) Å, c = 15.955(3) Å, β = 102.736(5)° for 2. The structures are made up of WO2Cl4 octahedra. In the case of 1 two octahedra are edge‐sharing via chlorine atoms to form pairs which are linked via the trans‐positioned oxygen atoms to form infinite double strands $^{\infty}_{1}\rm [W_{2}O_{4/2}Cl_{2/2}Cl_{4}]$. In the structure of 2 two of these double strands are condensed via terminal chlorine atoms to form quadruple strands $^{\infty}_{1}\rm [W_{4}O_{8/2}Cl_{6/2}Cl_{4}]$. Like for all members of the Mx[W2O2X6] structure family (X = Cl, Br) nonstochiometry with respect to the cations M was observed. The copper content of 1 and 2 was derived from the site occupation factors of the respective structure refinements. For several crystals examined the copper content varied between x = 0.27 and 0.17 for 1 and x = 0.04 for 2. In both structures the oxochlorotungstate strands are negatively charged and connected to layers by the monovalent copper ions, which are tetrahedrally coordinated by the non‐bridging chlorine atoms of the strands. The structure models imply disorder of the Cu+ ions over closely neighboured sites.