D. Shekhar Reddy

C–H ⋯ N mediated hexagonal network in the crystal structure of the 1 : 1 molecular complex 1,3,5-tricyanobenzene–hexamethylbenzene

Molecules of 1,3,5-tricyanobenzene are networked with C–H ⋯ N hydrogen bonds into a symmetrical hexagonal pattern in the crystal structure of the 1 : 1 complex formed by the compound with hexamethylbenzene.

The nature of halogen···halogen interactions and the crystal structure of 1,3,5,7-tetraiodoadamantane

An analysis of halogen ⋯ halogen (X ⋯ X) intermolecular interactions in crystals, using the Cambridge Structural Database (CSD). is presented. A total of 794 crystal structures yielded 1051 contacts corresponding to symmetrical and unsymmetrical X ⋯ X interactions of the type Cl ⋯ Cl, Br ⋯ Br, I ⋯ I, Cl ⋯ F, Br ⋯ F, I ⋯ F, Br ⋯ Cl, I ⋯ Cl and I ⋯ Br. These 1051 contacts are divided mainly into two categories, type I and type II depending upon the values of the two C–X ⋯ X angles θ1and θ2around the X atoms in a fragment of the type C–X ⋯ X–C. Type I contacts are defined as those in which θ1=θ2 while type II are defined as those in which θ1≅ 90° and θ2≅ 180°. Our results indicate that as the polarisability of the X atom increases, type II contacts become more significant than type I contacts and the X ⋯ X interaction may be more nearly considered to arise from specific attractive forces between the X atoms. A number of these concepts are succinctly illustrated in the crystal structure of 1,3,5,7-tetraiodoadamantane, 1. This structure has been reported to a very limited accuracy previously and the present work reveals an unusual twinned structure for this compound wherein the geometry of the stabilising I ⋯ I interactions is retained across the twin boundary. Compound 1 is tetragonal, space group I41/a, a= b = 7.1984(7) and c= 28.582(4)A, and Z = 4. The packing of the molecules in the crystal is controlled by I ⋯ I interactions. The supramolecular network of I ⋯ I connected molecules in crystalline 1 is closely related to that in adamantane-1,3,5,7-tetracarboxylic acid. Indeed, the stabilising nature of the I ⋯ I interactions is crucial for the crystallisation of 1 in this particular structure because otherwise, it should also have formed plastic crystals as do the analogous tetrachloro and tetrabromo derivatives.

Molecular networks in the crystal structures of tetrakis(4-iodophenyl)methane and (4-iodophenyl)triphenylmethane

The crystal structure of tetrakis(4-iodophenyl)methane is analysed in terms of molecular networks wherein the tetraphenylmethane moieties and I4 synthons are considered as molecular and supramolecular nodes. This I4 cluster plays the same role in generating molecular networks as does the Br4 cluster in the isomorphous tetrakis(4-bromophenyl)methane derivative. (4-Iodophenyl)triphenylmethane crystallises in a lower symmetry space group but features an unusual I···Ph interaction. In this series of halo-substituted tetraphenylmethanes the molecules exhibit similar columnar packing in the solid state, accounting for their crystallisation in non-centrosymmetric space groups.

N ··· Br mediated diamondoid network in the crystalline complex carbon tetrabromide: hexamethylenetetramine

CBr4 and hexamethylenetetramine cocrystallise to form a 1 : 1 molecular complex in which the component molecules are linked with N ⋯ Br interactions of 2.61(6)A to form two non-connected but catenated diamondoid networks.

Topological equivalences between organic and inorganic crystal structures: 1,3,5,7-tetrahydroxyadamantane and caesium chloride

The crystal structure of 1,3,5,7-tetrahydroxyadamantane has a network of O–H ⋯ O hydrogen bonds which is topologically equivalent to the eight-coordinated net in the CsCl family of solids.

Organic alloys: diamondoid networks in crystalline complexes of 1,3,5,7-tetrabromoadamantane, hexamethylenetetramine and carbon tetrabromide

1,3,5,7-Tetrabromoadamantane and hexamethylenetetramine (hmt) co-crystalline to form a diamondoid-type 1 : 2 molecular complex but one of the two hmt molecules is disordered and can be substitutionally replaced by CBr4 to give the corresponding 1 : 1 : 1 Complex.

Molecular and crystal structure of 1-(8-carboxyoctyl)-1,3,5,7-tetraazaadamantan-1-ium bromide and 1-(6-bromohexyl)-1,3,5,7-tetraazaadamantan-1-ium bromide

Abstract The molecular and crystal structures of a pair of quarternised bromide derivatives of hexamethylenetetramine have been determined. 1-(8-Carboxyoctyl)-1,3,5,7-tetraazaadamantan-1-ium bromide, 1, C14H27N4O2Br, Mr = 363.31, triclinic, P 1 , a = 9.759(5), b = 12.699(7), c = 14.125(6) A, α = 96.45(3), β = 99.17(3), γ = 104.74(3)°, V = 1649.7(14) A3, Z = 4, Dc = 1.463 g cm−3, λ(MoKα) = 0.7107 A, μ = 2.503 cm−1, F(000) = 760, R (on F) = 0.058, RW (on I) = 0.162 for 3625 unique reflections with [I –σ(I)]. There are two symmetry independent sets of ions, each set being linked with strong O⋯Br interactions to form linear arrays. The symmetry indenpendent arrays are in turn connected with CH⋯O interactions to form a layer. 1-(6-Bromohexyl)-1,3,5,7-tetraazaadamantan-1-ium bromide, 2, C12H29N4Br2, Mr = 384.17, monoclinic, P21/n, a = 8.976(4), b = 15.743(8), c = 11.329(6) A, β = 103.70(2)°, V = 1555.3(13) A3, Z = 4, Dc = 1.641 g cm−3, λ(MoKα) = 0.7107 A μ = 5.203 cm−1, F(000) = 776, R (on F) = 0.066, RW (on I) = 0.168 for 1310 unique non-zero reflections with [I⪢ 2σ(I)]. Two Br− anions are located between two cations resulting in the formation of a cyclic centrosymmetric dimer. Each dimer is surrounded by six similar dimers and is connected to them with CH⋯N hydrogen bonds to form corrugated molecular sheets. The symmetrical bond lengths of the hexamethylenetetramine skeleton are distorted by quarternisation in both 1 and 2.