Die Kristallstrukturen der Komplexe von 2,6-Dimethyl-γ-Pyron mit BF3, CuCl2 und HgCl2

Abstract

Abstract The crystal structures of the complexes of 2,6-dimethyl-4H-pyran-4-one (DMP) with BF3, CuCl2 and HgCl2 have been investigated. In all three case, the site of coordination is to the carbonyl (exocyclic) oxygen atom. DMP·BF3 (I) crystallizes with the monoclinic space group C2/c and the lattice parameters a = 1023.98(5), b = 1465.74(7), c = 1169.03(6) pm, β = 101.347(2)°. In this molecular structure the non-connected molecules are arranged in layers, which spread out parallel to the ab plane. Starting from planar BF3, this molecule is converted by coordination to a tetrahedral entity −OBF3. DMP·CuCl2 (II) belongs to the orthorhombic space group Pnma with a = 1952.43(9), b = 670.84(3), c = 1362.30(6) pm and two different Cu2+ cations. All atoms except the Cl− anions and two atoms of the −CH3 groups reside in mirror planes. The coordination around both Cu2+ cations is square pyramidal −OCuCl4 with the oxygen atom at the apex. The bases are planar and connected via trans-oriented edges to form a strand, running parallel to the b axis. DMP·HgCl2 (III) crystallizes with the space group P21/n and the lattice parameters a = 767.59(4), b = 1970.32(9), c = 1374.41(6) pm, β = 98.257(2)°. Its monoclinic structure is a distorted version of the orthorhombic copper(II) complex structure. The reason is the preference of Hg2+ for the short linear arrangement Cl−Hg−Cl. It is demonstrated, that the crystal structure of DMP·HgCl2 belongs to a translationsgleiche subgroup of the DMP·CuCl2 structure.