Untersuchungen an Polyhalogeniden, XXV [1]. Triiodide von Pyridinkomplexen des zweiwertigen Palladiums: Dipyridinpalladiumhexaiodid Pd(py)₂I₆ und zwei Formen des Tetrapyridinpalladiumhexaiodids Pd(py)₄I₆ / Studies on Polyhalides, XXV [1]. Triiodides of Pyridine Complexes of Divalent Palladium: Di(pyridine)palladium Hexaiodide Pd(py)₂I₆ and Two Forms of Tetra(pyridine)palladium Hexaiodide Pd(py)₄I₆

Two forms of the new compound Pd(py)₄I₆ have been prepared by the reaction of stoichiome­tric amounts of PdCl₂, C₅H₅N, KI and I₂ in water. One modification crystallizes triclinically in space group Ρ1̄ with a = 907.7(3), b = 960.5(7), c = 992.0(4) pm, α = 117.31 (4), β = 103.35(3), γ = 86.01(5)° and Z = 1, the other orthorhombically in space group Pnnm with a = 891.6(4), b = 1047.6(4), c = 1659.1(5) pm and Z = 2. Both structures may be described as layerlike packings of I₃^- anions and [Pd(py)₄]²⁺ cations. Differences arise from the orientations of the anions and cations within these layers.

The new compond Pd(py)₂l₆ has been prepared by recrystallisation of Pd(py)₄I₆ from chlo­roform. It crystallizes in the monoclinic space group I2/a with a = 1801.1(4), b = 584.0(1), c = 2220.5(6) pm, β = 115.78(2)° and Z = 2. The structure is built up from quasi square planar complexes [Pd(py)₂l₂] and iodine molecules I₂ linked together to give alternating screw- and zigzag-shaped chains ^[I^_-I₂] along [1 0 01 forming nets of type (10, 3) including the Pd²⁺ ions. The structure may also be described as a layerlike packing of the anionic chains ¹_∞[I^- · I₂] and linear complex cations [Pd(py)₂]²⁺ parallel [0 1 1].