Irina S. Konovalova

Analysis of the crystal structure of two polymorphic modifications of 3,4-diamino-1,2,4-triazole based on the energy of the intermolecular interactions

An X-ray diffraction study revealed the existence of 3,4-diamino-1,2,4-triazole in the crystal phase in two polymorphic modifications differing in the relative orientation of the molecules with respect to each other. A comparison of the character of the intermolecular interactions in the crystals of the polymorphic modifications suggests that polymorphism may be due to the formation of different weak hydrogen bonds while stronger H bonds and stacking interactions are similar in the two crystal structures. Calculations of the intermolecular interaction energy by the MP2/aug-cc-pvdz method allows determination in both crystal layers containing the strongly bonded molecules differing in the two polymorphic modifications. This approach distinguishes unambiguously the main structural pattern of packing of the molecules in the crystals of both polymorphic modifications.

Intra- and Intermolecular Interactions in the Crystals of 3,4-Diamino-1,2,4-triazole and Its 5-Methyl Derivative. Experimental and Theoretical Investigations of Charge Density Distribution

In this paper intra- and intermolecular interactions in crystals of 3,4-diamino-1,2,4-triazole (DAT) and its 5-methyl derivative (DAMT) were investigated in details by experimental (high-resolution X-ray diffraction) and theoretical (ab initio quantum chemistry (MP2/aug-cc-pvdz), AIM, and NBO) methods. Influence of n-π conjugation and n→σ* hyperconjugation on the geometry of DAT and DAMT molecules was shown. All intermolecular interactions in crystals of the DAT and DAMT including weak X-H···π and mixed X-H···N/X-H···π hydrogen bonds were considered. Comparison of BCP characteristics of these interactions from experimental and theoretical charge density distribution demonstrates systematic increase of bonding in isolated dimers compared with dimers in the crystal phase. The ability of amino groups in both crystals serve as proton acceptors in hydrogen bonding was confirmed.

Remarkably strong polarization of amidine fragment in the crystals of 1-imino-1H-isoindol-3-amine

Results of the X-ray diffraction studies of 1-imino-1H-isoindol-3-amine and its derivatives reveal unusual distribution of bond lengths within the NH2–C=N amidine fragment in the considered crystals. In the crystal phase, single C–N bond is shorter or at most has the same length as double C=N bond, while in isolated molecules both these bonds have expected lengths, according to the calculations by MP2/6-311G(d,p) and MP2/cc-pvtz methods. It is demonstrated that so unusually strong polarization of the amidine fragment is induced by polar environment in solid state. This effect stabilizes the amino-imino tautomer of 1-imino-1H-isoindol-3-amine, which becomes more stable than the diimino tautomer possessing the lowest energy in the gas phase.

catena-Poly[neodymium(III)-bis­[μ-N-(dimorpholinophosphor­yl)benzene­sulfonamidato]-sodium(I)-bis­[μ-N-(dimorpholinophosphor­yl)benzene­sulfonamidato]]

The cubic crystal structure of the title compound, [NaNd(C14H21N3O5PS)4]n, is composed of one-dimensional polymeric chains propagating in [100], built up from [Nd(C14H21N3O5PS)4]− anions and sodium cations functioning as linkers. In the complex anion, the Nd3+ ion has an eightfold coordination environment formed by the sulfonyl and phosphoryl O atoms of four bidentate chelating N-(dimorpholinophosphoryl)benzenesulfonamidate ligands: the resulting NdO8 polyhedron can be described as intermediate between dodecahedral and square antiprismatic. The sodium ion adopts an NaO4 tetrahedral geometry arising from four monodentate benzenesulfonamidate ligands. The resulting crystal structure is unusual because it contains substantial voids (800 Å3 per unit cell), within which there is no evidence of included solvent.

cis-Diaqua-bis-[dimethyl (phenyl-sulfonyl-imino)-phospho-nato]cobalt(II).

In the title diaquacobalt complex, [Co(C8H11NO5PS)2(H2O)2], the CoII atom is surrounded by six O atoms belonging to the phosphoryl and sulfonyl groups of two deprotonated chelate ligands and two additional O atoms from water molecules which are in cis positions with respect to one another. The coordination environment of cobalt can be described as a distorted octahedron. O—H⋯O hydrogen bonds between the water and sulfonyl O atoms of neighboring molecules form chains running parallel to [010]. Two methoxy groups attached to one phosphorus are disordered over two sets of sites in a 0.6:0.4 ratio.

Acceptor properties of amino groups in aminobenzene crystals: study from the energetic viewpoint

Acceptor properties of the amino groups of aniline and ortho, meta and para-diaminobenzenes in the crystal phase have been studied through the analysis of their crystal structures based on comparison of interaction energies in a crystal. Analysis of pairwise interaction energies allowed recognition of the basic structural motifs (BSMs) and determination of the types of hydrogen bonds which cause the bonding of the molecules within the BSMs and between neighboring ones. The N–H⋯N hydrogen bonds where the nitrogen lone pair is a proton acceptor were shown to be present in all studied crystals and played different roles in crystal packing. The N–H⋯N hydrogen bonds form the building unit and the primary structural motif in two polymorphic modifications of ortho-diaminobenzene. In the crystal of meta-diaminobenzene, the N–H⋯N interactions role is comparable with that of the N–H⋯π hydrogen bonds. Both these interactions form the primary basic structural motifs. Finally, the N–H⋯N hydrogen bonds have a minor role in the crystals of aniline and para-diaminobenzene where these interactions ensure bonding between secondary basic structural motifs. The crystals of the monoclinic and orthorhombic polymorphs of aniline as well as para-diaminobenzene differ from each other by mutual arrangement of the secondary basic structural motifs.

catena-Poly[sodium-di-μ-aqua-sodium-bis[μ-2,2,2-trichloro-N-(dimorpholinophosphoryl)acetamide]]

The title compound, [Na2(C10H16Cl3N3O4P)2(H2O)2]n, can be considered as a two-dimensional coordination polymer in which one-dimensional chains are connected to each other by intermolecular C—H⋯O hydrogen bonds involving the water molecules. The NaI ion is five-coordinated in a distorted trigonal-bipyramidal geometry. The connection between the two NaI ions is facilitated by the two μ-O atoms of the carbonyl group of the 2,2,2-trichloro-N-(dimorpholinophosphoryl)acetamide (CAPh) ligand. A bridging coordination of the CAPh ligand via the carbonyl O atom is observed for the first time. The bridging water molecules form intermolecular O—H⋯O hydrogen bonds with the O atoms of the morpholine rings and the phosphoryl groups of neighboring CAPh molecules.

2-Hydroxy­imino-N′-[1-(2-pyrid­yl)ethyl­idene]propanohydrazide

The title compound, C10H12N4O2, features an intramolecular N—H⋯N hydrogen bond formed between the imine NH and oxime N atoms. The oxime group and the amide C=O bond are anti to each other. In the crystal, molecules are connected by O—H⋯O hydrogen bonds into supramolecular zigzag chains along the c axis.

catena-Poly[calcium-bis­[μ-N-(dimethyl­phosphino­yl)benzene­sulfonamidato]]

The crystal structure of the title calcium complex, [Ca(C8H11NO5PS)2]n, is composed of a polymeric chain, which is formed due to two bridging sulfonyl groups linking CaII ions in a O—S—O—Ca manner. Thus, the coordination environment of the CaII ions is composed of six O atoms belonging to the phosphoryl and sulfonyl groups of two chelate rings and two additional O atoms of two bridging sulfonyl groups. The coordination polyhedron of the central atom (2 symmetry) has a distorted octahedral geometry.

Crystal structure of {μ-6,6′-dimeth­oxy-2,2′-[ethane-1,2-diylbis(nitrilo­methanylyl­idene)]diphenolato}(meth­anol)(nitrato)nickel(II)sodium

Two phenolate O atoms provided by a Schiff base ligand create a double bridge between Ni2+ and Na+ ions. The coordination environment of the Ni2+ ion is square-planar and it has an unusual seven-coordinated geometry: four atoms from the Schiff base ligand, two from a nitrate anion, which coordinates in a bidentate chelating mode, and one O atom from the coordinated methanol molecule. C—H⋯O weak hydrogen-bond interactions result in the formation of chains along the b-axis direction which are further assembled by bifurcated O—H⋯O hydrogen bonds and π-stacking interactions.