Structure of bis-(4-methylpyridine)dichlorocopper(II): a dislocated linear chain

Abstract

The crystal and molecular structure of bis(4-methylpyridine)dichlorocopper(II), Cu(C 6H 7N) 2Cl 2, has been determined from three-dimensional photographic X-ray data obtained from a twinned and highly mosaic crystal. The complex crytallizes in space group P2 1/c of the monoclinic system with two formula units in a cell of dimensions a = 9.745(7), b = 3.932(4), c = 19.035(9) Å, β = 111.8(2)°. The observed diffraction pattern, however, is nearly consistent with orthorhombic symmetry and the space group Cmma. The chain axis is parallel to the monoclinic crystallographic b-axis, and the twinning occurs perpendicular to this axis; the twinning causes dislocations in the chain by limiting the chain lengths to the sizes of the ordered crystal domains along the chain axis. The geometry at each copper atom is (4 + 2) tetragonally-elongated octahedral, the in-plane ligands being two trans-nitrogen atoms [CuN =2.07(3) Å] and two trans-chlorine atoms [CuCl =2.35(1) Å]. The axial ligands are symmetry-related chlorine atoms, which are in-plane ligands of the adjacent copper atoms in the chain, the axial CuCl and CuCu′ distances being 3.19(1) and 3.932(4) Å, respectively. Each chain is very similar to that found in the analogous pyridine complex, but the arrangement of the chains in the crystal is more like that in the thiazole complex Cu(thz) 2Cl 2.