Structural and theoretical analysis of 2-chloro-4-nitroaniline and 2-methyl-6-nitroaniline salts.

The crystal structures of five new salts of 2-chloro-4-nitroaniline (2Cl4na) and 2-methyl-6-nitroaniline (2m6na) with inorganic acids, namely, 2-chloro-4-nitroanilinium bromide, CHClNO·Br (1), 2-chloro-4-nitroanilinium hydrogen sulfate, CHClNO·HSO (2), 2-methyl-6-nitroanilinium bromide, CHNO·Br (3), 2-methyl-6-nitroanilinium triiodide, CHNO·I (4), and 2-methyl-6-nitroanilinium hydrogen sulfate, CHNO·HSO (5), were determined by single-crystal X-ray diffraction. Theoretical calculations of the relaxed potential energy surface (rPES) revealed that the energy barriers for the rotation of the nitro group for isolated H2Cl4na and H2m6na cations are 4.6 and 11.

Structural, theoretic and spectroscopic analysis of 2-methyl-5-nitroaniline salts with various inorganic acids.

Crystal structures of six new salts of 2-methyl-5-nitroaniline with inorganic acids [(H2Me5NA)Br, (H2Me5NA)I, (H2Me5NA)NO, (H2Me5NA)Cl, (H2Me5NA)HSO and (H2Me5NA)I·0.5HO] are determined by single-crystal X-ray diffraction. The most important hydrogen-bonding patterns are formed by the ammonio group and respective anions composing 1D or 2D networks.

Role of supramolecular synthons in the formation of the supramolecular architecture of molecular crystals revisited from an energetic viewpoint.

Analysis of the strengths and directionality of intermolecular interactions in the crystals containing only one type of supramolecular synthon allows the suggestion of a general classification of molecular crystals depending on type of their basic structural motifs. All crystals may be divided on four classes namely (I) crystals with isotropic packing of the building units; (II) columnar crystals where the basic structural motif (BSM) is a chain/column; (III) layered crystals with layers as the BSM; (IV) columnar-layered crystals containing chains/columns as the primary basic structural motif and layers as the secondary BSM. Taking into account the participation of different supramolecular synthons in the formation of different levels of the organization of molecular crystals, they may be considered as basic (responsible for the formation of molecular complexes as building units of crystals), primary, secondary and auxiliary, which are involved in the agglomeration of molecules in primary or secondary basic structural motifs or in the packing of these motifs, respectively.

Methyl N-(3-cyano-picolino-yl)-l-tryptophanate.

In the title compound, C19H16N4O3, the stereocenter has an l configuration; l-tryptophan methyl ester hydro-chloride being used as a starting material. The indole ring system and the pyridine ring are inclined to one another by 13.55 (14)°.

Tris[dimethyl (benzoyl-amido)-phosphato-κ(2) O,O'](1,10-phenanthroline-κ(2) N,N')neodymium(III).

In both independent mol-ecules of the title compound, [Nd(C9H11NO4P)3(C12H8N2)], the Nd(III) atom is coordinated by six O atoms belonging to three phosphoryl ligands and two N atoms of 1,10-phenanthroline in a dodeca-hedral geometry. In the phosphoryl ligands, the benzene rings are twisted with respect to the planes of the sp(2)-hybridized C atoms of the chelate rings by 12.1 (1)-24.