Reactions of CuI with N-methylpyrazinium iodide, (pyr)I, N-methyl-4,4′-bipyridinium iodide, (bp4)I and N-methyl-2,2′-bipyridinium iodide, (bp2)I, in organic solvents led to three novel types of copper(I) complexes of stoichiometries (pyr)Cu2I3, (bp4)Cu3I4 and (bp2)Cu2I3. In all of them the cations are n-σ-bonded to copper(I) through donation of their unshared electron pairs. (pyr)Cu2I3 crystallizes with an ionic structure (trigonal, R 3 c, hexagonal axes a = 3053(2), c = 671.9(3) pm, Z = 18). Polymeric cations ∞1[((pyr)CuI3/3)3]3+ and anions ∞1[CuI4/2]-form parallel rod packings. The structure motif of the cations can be described as a columnar part of the β-CuI structure in which the copper and iodine atoms are also arranged to Cu3I3 rings.The crystal structure of (bp4)Cu3I4 (triclinic, P Ī, a = 938.8(2), b = 980.0(4), c = 1070.1(3) pm, α = 73.56(3), β = 75.79(2), γ = 89.50(3)°, Ζ = 2) is built up by uncharged chains ∞1[(CuI4/3)(CuI3/3I1/2)((bp4)CuI2/3I1/2)]. The trinuclear units (bp4)Cu3I4 are connected via common iodide edges. The copper halide connection motif of the polymeric compound has some features in common with the “stair” and “cube” structures of adducts of CuI with unidentate, neutral P-, As- or N-bases.The compound (bp 2)Cu2I3 (monoclinic, P 21/n, a = 1054.0(2), b = 1034.8(3), c = 1512.6(3) pm, β = 108.10(2)°, Ζ = 2) has a structure, in which two edge-sharing (CuI4/2)-tetrahedra and two approximately planar (CuI2/2(bp 2))-units form tetranuclear molecules (bp 2)2Cu4I6. These are linked to chains with a “stair” motif by intermolecular Cu ··· I contacts.
Synthesis, Crystal Structure, UV–Vis Adsorption Properties, Photoelectric Behavior, and DFT Computational Study of All-Inorganic and Lead-Free Copper Halide Salt K2Cu2Cl6