Krzysztof Ejsmont

The enrichment ratio of atomic contacts in crystals, an indicator derived from the Hirshfeld surface analysis

An enrichment ratio is derived from the decomposition of the crystal contact surface between pairs of interacting chemical species. The propensity of different contact types to form is investigated.

On polymorphic and non-polymorphic conversions of phthalocyanines

Abstract The X-ray and IR spectra of metal-free phthalocyanine show that the x-form of H 2 Pc is β-Pc. X-ray measurements of the β-form of MgPc reveal that alteration to the so-called α-form of MgPc occurs in air. Continued cycling of the sample between vacuum and air demonstrated the reversibility of this process. It has been concluded, that, in general, α-forms of M(II)Pc are not pure phthalocyanines, but are complexes of M(II)Pc with N 2 and O 2 molecules.

Structural and Molecular Characterization of meso-Substituted Zinc Porphyrins: A DFT Supported Study

Structural parameters of a range of over 100 meso-substituted zinc porphyrins were reviewed and compared to show how far the nature of the functional group may affect the interatomic distances and bond angles within the porphyrin core. It was proved that even despite evident deformations of the molecular structure, involving twisting of the porphyrins central plane, the coupled π-bonding system remains flexible and stable. DFT calculations were applied to a number of selected porphyrins representative for the reviewed compounds to emphasize the relevance of theoretical methods in structural investigations of complex macrocyclic molecular systems. Experimental and DFT-simulated IR spectral data were reported and analyzed in context of the individual molecular features introduced by the meso substituents into the porphyrin moiety base. Raw experimental spectral data, including 1H- and 13C-NMR, UV-Vis, FTIR, XRD, and other relevant physicochemical details have been provided for a specially chosen reference zinc porphyrin functionalized by tert-butylphenyl groups.

N′-(2-Fluoro­benzo­yl)benzohydrazide

In the crystal structure of the title compound, C14H11FN2O2, the molecule is centrosymmetric. The F atom is disordered over four positions, on the two ortho positions of each ring, with occupancies of 0.287:0.213 (5). In the crystal structure, molecules are linked by intermolecular N—H⋯O and C—H⋯O hydrogen bonds.

Cage-annulated thiacrown ethers and thiacryptands

AbstractA series of cage-annulated sulfur-containing crown ethers and cryptands have been synthesized as possible specific metal host systems. The synthesis and structures of seven compounds are described, including a thiacryptand complex with Hg(II). The trishomocubane cage is essentially spherical except for a methylene group, which imparts no steric restrictions, and two disordered superimposed orientations occur in most structures. This superposition of four- and five-membered rings usually cannot be resolved into separate entities, resulting in distorted distances, angles, and thermal parameters for the cage. (3) I41cd, a = 13.207(3) Å, b = 13.207(3) Å, c = 35.876(12) Å; (10) C2, a = 14.551(2) Å, b = 10.028(1) Å, c = 10.491(1) Å, β = 107.108(2)°; (14) P21/n, a = 10.6277(8) Å, b = 9.8488(7) Å, c = 21.822(2) Å, β = 97.945(2)°; (19) P21/c, a = 15.381(3) Å, b = 6.667(1) Å, c = 18.158(3) Å, β = 94.838(4)°; (25) C2/c, a = 34.386(4) Å, b = 11.318(1) Å, c = 13.409(2) Å, β = 110.044(2)°; (28)

Halogen effect on structure and 13C NMR chemical shift of 3,6-disubstituted-N-alkyl carbazoles.

P\bar 1

4-Chloro-N-methyl-N-nitroaniline

, a = 10.4487(8) Å, b = 11.5677(9) Å, c = 13.354(1) Å, α = 71.042(1)°, β = 87.344(1)°, γ = 65.839(1)°; (29) P21/c, a = 10.8138(5) Å, b = 16.4949(8) Å, c = 22.054(1) Å, β = 96.087(1)°.

CO substitution in Ru3(CO)12 by 2,3-bis(diphenylphosphino)-N-phenyl-maleimide (bppm). X-ray diffraction structure of Ru2(CO)6(bppm)

X-ray analysis of N-(4-fluorophenyl)-1,5-dimethyl-1H-imidazole-4-carboxamide 3-oxide reveals the temperature-dependent polymorphism associated with the crystallographic symmetry conversion. The observed crystal structure transformation corresponds to a symmetry reduction from I41/a (I) to P43 (II) space groups. The phase transition mainly concerns the subtle but clearly noticeable reorganization of molecules in the crystal space, with the structure of individual molecules left almost unchanged. The Hirshfeld surface analysis shows that various intermolecular contacts play an important role in the crystal packing, revealing graphically the differences in spatial arrangements of the molecules in both polymorphs. The N-oxide oxygen atom acts as a formally negatively charged hydrogen bonding acceptor in intramolecular hydrogen bond of N–H…O− type. The combined crystallographic and theoretical DFT methods demonstrate that the observed intramolecular N-oxide N–H…O hydrogen bond should be classified as a very strong charge-assisted and closed-shell non-covalent interaction.