Synthesis and crystal structures of Cd[AlCl₄]₂ and Cd₂[AlCl₄]₂

Abstract

Abstract Colorless single crystals of Cd[AlCl 4 ] 2 grow from the melt of CdCl 2 and AlCl 3 upon slow cooling from 250°C. The crystal structure [monoclinic, P1a1, Z = 2, a = 1288.7(2), b = 660.2(1), c = 705.1(1) pm, β = 92.89(1)º] may be derived from hexagonally closest packed layers of Cl − . Octahedral and tetrahedral holes are filled with Cd 2+ and Al 3+ in a 1:2 ratio between all layers stacked in the [104] direction. Cd[GaCl 4 ] 2 and Cd[AlBr 4 ] 2 are isotypic. Reduction of Cd[AlCl 4 ] 2 with excess cadmium shot and slow cooling from 350°C yields plate‐like very moisture‐sensitive, colorless single crystals of Cd 2 [AlCl 4 ] 2 . The crystal structure [triclinic, C 1 , Z = 2, a = 655.47(3), b = 1135.26(1), c = 935.23(6) pm, α = 89.70(2)º, β = 103.61(1)º, γ = 90.455(1)º] is built from slabs stacked in the [100] direction consisting of ethane‐like [Cd 2 Cl 6 ] units with a CdCd distance of 256.1 pm sharing common vertices with [AlCl 4 ] tetrahedra.