title: Flexibility of CuCl4-tetrahedra in bis[cinchoninium tetrachlorocuprate(II)]trihydrate single crystals. X-ray diffraction and EPR studies.
abstract: Crystal structure of bis[cinchoninium tetrachlorocuprate(II)] trihydrate, [(C19H24N2O)CuCl4]2-3H2O, has been determined by X-ray diffraction at 100 K and reexamined at 293 K. The compound crystallizes in orthorhombic system with a P2(1)2(1)2(1) space group and unit cell parameters a = 15.3031(14), b = 36.415(3), and c = 7.8341(5) A at 100 K, and Z = 4. The asymmetric unit consists of two (CuCl4)(2-) tetrahedral anions linked by hydrogen bonds to two doubly protonated cinchonine molecules and three water molecules. The tetrahedra are strongly flattened, to approximately D(2d) symmetry, with different deformation for two inequivalent (CuCl4)(2-) -ions in the asymmetric unit. The deformation of (CuCl4)(2-) and cinchoninium cations varies with temperature due to a rearrangement of the bifurcated hydrogen bond network. This is a continuous process observed as a monotonic variation of the EPR spectral parameters and the unit cell dimensions. EPR spectra show that very weak exchange coupling J(12) = 0.0030 cm(-1) operates between Cu(2+) ions within asymmetric units, corresponding to the general formula of the compound, as well as between equivalent Cu(2+) sites of different molecules, whereas the coupling is negligible between inequivalent sites. The intermolecular J(12) coupling is temperature-independent indicating that the whole asymmetric unit behaves as a magnetic unit (pseudodimer) in the whole temperature range.
authors.affiliation: Regional Laboratory of Physicochemical Analyses and Structural Research and Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland. birczyns@chemia.uj.edu.pl
authors.forename: A
authors.initials: A
authors.lastname: Wesełucha-Birczyńska
authors.forename: B J
authors.initials: BJ
authors.lastname: Oleksyn
authors.forename: S K
authors.initials: SK
authors.lastname: Hoffmann
authors.forename: J
authors.initials: J
authors.lastname: Sliwiński
authors.forename: B
authors.initials: B
authors.lastname: Borzecka-Prokop
authors.forename: J
authors.initials: J
authors.lastname: Goslar
authors.forename: W
authors.initials: W
authors.lastname: Hilczer
mesh_terms: D002930:Cinchona Alkaloids / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D011812:Quinuclidines / Q000737:chemistry*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D002930:Cinchona Alkaloids; D009942:Organometallic Compounds; D011812:Quinuclidines; C436496:bis(cinchoninium tetrachlorocuprate(II)) trihydrate; D003300:Copper