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Hydrogen bonds are considered a powerful organizing force in designing supramolecular architectures because they are directional, selective and reversible at room temperature. trans-Dithiocyanatotetrakis(4-vinylpyridine)nickel(II) is a popular host for the inclusion of small molecules and 2,3,5,6-tetrafluoro-1,4-diiodobenzene (TFDIB) represents a strong halogen-bond donor. These constituents cocrystallize in a 1:1 stoichiometry, [Ni(NCS)2(C7H7N)4]·C6F4I2, in the tetragonal space group I41/ a. Both residues occupy special positions, i.e. the pseudo-octahedral NiII complex is located on a twofold axis and the TFDIB molecule sits about a crystallographic centre of inversion. The components interact via a short S...I contact of 3.2891 (12) Å between the thiocyanate S atom of the host and the iodine substituent at the perhalogenated aromatic ring of the smaller guest molecule. This interaction meets the commonly accepted criteria for a halogen bond. Such halogen bonds to sulfur are significantly less common than to smaller electronegative atoms. [ABSTRACT FROM AUTHOR]

In catena-poly[copper(II)-di-μ-chlorido-μ-proline-κ2 O: O′], [CuCl2(C5H9NO2)] n, two symmetry-independent metal cations adopt distorted octahedral coordination, typical for d9 Jahn-Teller systems. Each chloride bridge is involved in both a short and a very long interaction with a CuII centre. The centrosymmetric crystal structure contains homochiral chains of opposite handedness which extend along the shortest lattice parameter ( i.e. a). The O: O′-bridging coordination mode of proline, although a common motif for such complexes in general, is remarkable for CuII; the vast majority of amino acid derivatives of this cation are characterized by N, O-chelation. [ABSTRACT FROM AUTHOR]

In catena-poly[copper(II)-di-μ-chlorido-μ-proline-κ2 O: O′], [CuCl2(C5H9NO2)] n, two symmetry-independent metal cations adopt distorted octahedral coordination, typical for d9 Jahn-Teller systems. Each chloride bridge is involved in both a short and a very long interaction with a CuII centre. The centrosymmetric crystal structure contains homochiral chains of opposite handedness which extend along the shortest lattice parameter ( i.e. a). The O: O′-bridging coordination mode of proline, although a common motif for such complexes in general, is remarkable for CuII; the vast majority of amino acid derivatives of this cation are characterized by N, O-chelation. [ABSTRACT FROM AUTHOR]

The crystal structure of the title compound, [Cu(ClO4)2(C4H12N2)2], (I), is reported at 100, 250 and 400 K. The CuII cation in this complex is coordinated in a distorted octahedral mode characteristic of Jahn-Teller systems. The coordination of the perchlorate ligands via longer, and presumably weaker, axial Cu-O distances varies significantly as a function of temperature. One of the Cu-O distances increases between 100 and 250 K, and one of the Cu-O-Cl angles expands between 250 and 400 K. At all temperatures, the complex forms a two-dimensional N-H...O hydrogen-bond network in the (001) plane. [ABSTRACT FROM AUTHOR]

N, N-Dimethylbiguanidinium bis(hydrogensquarate) features an impressive range of hydrogen bonds within the same crystal structure: neighbouring anions aggregate to a dianionic pair through two strong O-H...O interactions; one of these can be classified among the shortest hydrogen bonds ever studied. Cations and anions in this organic salt further interact via conventional N-H...O and nonclassical C-H...O contacts to an extended structure. As all these interactions occur in the same sample, the title compound is particularly suitable to monitor even subtle trends in hydrogen bonds. Neutron and high-resolution X-ray diffraction experiments have enabled us to determine the electron density precisely and to address its properties with an emphasis on the nature of the X-H...O interactions. Sensitive criteria such as the Laplacian of the electron density and energy densities in the bond-critical points reveal the incipient covalent character of the shortest O-H...O bond. These findings are in agreement with the precise geometry from neutron diffraction: the shortest hydrogen bond is also significantly more symmetric than the longer interactions. [ABSTRACT FROM AUTHOR]

In the title complex {[Cu(ClO4)(C12H8N2)(CH3CN)2]ClO4} n, the Cu cations have an N4O2 octahedral coordination geometry, being bridged by the perchlorate, chelated by the phenanthroline heterocycles and also coordinated by two acetonitrile ligands. One perchlorate anion acts both as a bridging bis-monodentate ligand between a metal cation and its symmetry equivalents, forming an infinite one-dimensional chain in the b-axis direction, and as a counter-ion to balance the charge. [ABSTRACT FROM AUTHOR]

In the title complex, [Cu(C12H8N2)2(CH3CN)](ClO4)2, the five-coordinate CuII ion has a distorted square-pyramidal coordination geometry composed of five N atoms, four from two bidentate chelating phenanthroline ligands and one from acetonitrile. The acetonitrile molecule and the Cu atom are situated on a crystallographic twofold rotation axis. [ABSTRACT FROM AUTHOR]