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The crystal structure of (μ 3 -oxo)hexakis(cyanoacetato-κO,O′)(cyanoacetato-κO)diaquatriiron(III) cyanoacetic acid shows the formation of trinuclear complexes in a hydrogen-bond network that bonds all the molecules in a 3D arrangement. For this complex, within whose clusters the whole magnetic interaction takes place, 57 Fe Mössbauer spectroscopy shows that the Fe cations are in the S = 5/2 state in the temperature range 2–295 K. The asymmetric broadening of the absorption peaks below 80 K is consistent with strong antiferromagnetic interactions between the metal spins. The magnetization measurements also show the antiferromagnetic character of the spin ensemble and an S T = 1/2 magnetic ground state typical of triangular systems with similar J between Fe-Fe pairs. [ABSTRACT FROM AUTHOR]

A new copper(II) complex of formula {[Cu 2 (H 2 btc) 2 (dmf) 2 ]·4dmf} n ( 1 ) [H 4 btc = 1,2,4,5-benzenetetracarboxylic acid, dmf = dimethylformamide] has been synthesised and its structure determined by X-ray diffraction. The structure displays a new square grid of “paddle-wheel” tetracarboxylate-bridged dicopper(II) units with an intradimer copper–copper separation of 2.619(2) Å. The dmf molecules are retained through weak axial coordinative bonds and hydrogen bonding interactions with the carboxylic groups of the porous neutral network of 4 4 net topology. The magnetic behaviour of 1 corresponds to a strong antiferromagnetic coupling within each dicopper(II) unit ( J = −343 cm −1 with the Hamiltonian being defined by H = − J S 1 · S 2 ). Complex 1 does not adsorb N 2 but it exhibits certain absorption of CO 2 with a hysteretic desorption behaviour typical of flexible MOFs. [ABSTRACT FROM AUTHOR]

This study aims to investigate the molecular structure and polymorphism of trans-1,4-cyclohexanedimethanol, including the bi-axial/bi-equatorial equilibrium and the nature of the intermolecular H-bond networks in condensed phases created by the hydroxyl group torsions. The full conformational space of the single molecule was explored by MP2 calculations, showing that the optimized bi-equatorial conformers have similar stability and the bi-axial ones have much higher energies. The hydroxymethyl substituents have preference for gauche/anti or gauche+/gauche- conformations. Polymorphic forms were generated by crystallization from solutions and by cooling the melt, which were characterized by a combination of techniques: DSC, PLTM and XRD. Two polymorphs were isolated and their crystal structures were solved by direct methods based on single-crystal X-ray analysis. Both were found to contain two of the most stable conformers found in the computational calculations. The influence of H-bonding in the polymorphic structures was verified by analysis of the structural differences between the geometries present in the polymorphs determined by XRD and their single molecule counterparts resulting from the theoretical calculations. The bi-axial conformations are destabilized over the bi-equatorial ones in isolated and crystalline forms of trans-1,4-cyclohexanedimethanol. [ABSTRACT FROM AUTHOR]

A series of thermotropic hydrogen-bonded liquid crystalline structures based on 4,4′-bipyridyl and aliphatic carboxylic acids was prepared by a mechanosynthesis technique. This series was characterised by polarising optical microscope, differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray powder diffraction and1H NMR relaxometry experimental techniques. In these complexes, the bipyridyl component, a non-mesogenic substance by itself, acts as a double H-bond acceptor, whereas the alkylbenzoic acid acts as a H-bond donor, in a 1:2 proportion. The so-formed complexes exhibit mesophases that are not observed by the single components. A characteristic phase (smectic A) is identified and shown to be affected by the alkyl chain length. The isotropisation temperature is increased by the supramolecular aggregation through the H-bonds. [ABSTRACT FROM PUBLISHER]

2-Chloro-1,3-dioxo-2,3-dihydro-1 H-inden-2-yl acetate, CHClO (Fig. 1), has been synthesized and the structure has been solved by IR and X-ray diffraction studies. The crystals are triclinic, space group P $$ \bar{1} $$, with a = 7.62060(10) Å, b = 11.5944(2) Å, c = 13.0753(3) Å, α = 97.2820(10)°, β = 101.5740(10)°, γ = 101.7930(10)°, Mr = 238.62, V = 1090.82(3) Å, Z = 4 and R = 0.0557. In the title compound there are two molecules in the asymmetric unit. The molecules are linked via weak C-H···O hydrogen bonds forming R(28) rings. The intermolecular interactions were analysed by means of the fingerprint plots derived from the Hirshfeld surfaces. The fingerprint plots evidenced subtle differences in the intermolecular contacts for the two independent molecules.[Figure not available: see fulltext.] Graphical Abstract: The structure of 2-chloro-1,3-dioxo-2,3-dihydro-1 H-inden-2-yl acetate has two molecules in the asymmetric unit. The crystal packing is stabilized only by weak interactions. Ab nitio calculations for the free molecule show that the crystal packing has little influence on the molecular conformation.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The title compound, C23H30N2O3, prepared in a one-step reaction from the commercially available 1,10-carbonyldiimidazole (CDI) and testosterone,crystallizes with two independent molecules in the asymmetric unit. The imidazole carbonyloxy group is in an equatorial position. The molecules are joined in layers parallel to the ac plane via C—H⋯O intermolecular interactions. [ABSTRACT FROM AUTHOR]

In the solid state, the title compound, C15H23NO4, forms centrosymmetric dimers in which individual mol­ecules are linked by intermolecular N—H⋯O hydrogen bonds. The pyrrole ring is planar within 0.004 (9) Å. [ABSTRACT FROM AUTHOR]

Examines the hydrogen-bonding interactions in ethyl 4-acetyl-5-methyl-3-phenyl-1H-pyrrole-2-carboxylate monohydrate. Link between hydrogen bonds, substituted pyrrole and water molecules to form infinite chains; Molecular structure; Weighted average of the absolute torsion angles of the pyrrole ring.

Describes the crystal structure of the compound, ethyl 4-dodecyl-3,5,-dimethyl-1H-pyrrole-2-carboxylate. Intermolecular interactions in an amphiphilic pyrrole; Synthesis of Langmuir-Blodgett films of porphyrins; Hydrogen-bonding capability of the aromatic electron clouds; Formation of carbon chains.

In the title compound, C14H15NO, the molecules are joined via C—H...O interactions into chains along the b axis. The planes of the pyrrole and benzene rings are at an angle of 62.17 (10)° with respect to each other. [ABSTRACT FROM AUTHOR]

Abstract: A new polymorph of N′,N″,N″′-triphenylbiuret, C20H17N3O2 (form II), has been synthesized and the structure has been solved by X-ray diffraction. The crystals are monoclinic, space group P21/c, with a =7.6966 (3)Å, b =12.5490 (4)Å, c =18.5996 (6)Å, β =107.632(2)°, Mr =331.37, V =1712.04 (10)Å3, Z =4 and R =0.0454. The hydrogen bonding of this polymorph is considerably different from that of the previously known structure. The molecules are linked in infinite chains, via C–H⋯O hydrogen bonds and there is also an intramolecular N–H⋯O hydrogen bond. The intermolecular interactions present in this polymorph, and on the previously reported polymorph, were analysed by means of the fingerprint plots derived from the Hirshfeld surfaces. The fingerprint plots evidenced the different packing modes of the two structures. Quantum–mechanical ab initio calculations for the free molecule were performed using the Hartree–Fock and DFT/B3LYP methods with the 6-31G(d,p) basis set of wave functions. The solid-state conformations compared with those obtained theoretically from DFT calculations for the isolated molecules show significant differences. Some difficulties of using quantum–mechanical calculations for the determination of relative conformational energies are also discussed. [Copyright &y& Elsevier]