NMR and XRD Study of Hydrogen Bonding in Picolinic Acid N-Oxide in Crystalline State and Solutions: Media and Temperature Effects on Potential Energy Surface.

Solvent and temperature effects on H-bonding in crystalline picolinic acid N-oxide (PANO) and in solutions were studied by NMR (1H MAS and 1H-13C CP/MAS) and X-ray diffraction (XRD) methods. The single-crystal XRD experiments on ß-polymorph were carried out at 105 and 299 K. 13C chemical shifts of PANO pyridine ring carbons were chosen as an effective diagnostic tool for the H-bond sensing. The crystal field in PANO forces the proton displacement from donor to acceptor atoms much stronger than the solvent reaction field, including that created by the most polar solvents. NMR and XRD data for crystalline PANO do not confirm any H-bond geometry changes in the studied temperature range. On the contrary, a considerable contraction of r(O-H) bond was observed for PANO in acetonitrile (ACN) solution upon heating. The relative contraction of r(O-H) bond with respect to R(O···O) perfectly fits the global dielectric scheme deduced for a vast set of common solvents and the dependence of the dielectric permittivity of ACN on temperature. The subtle H-bond changes can be explained by the temperature dependence of the shape of potential energy surface in the liquid state. Both factors, temperature and dielectric permittivity, are comparable in triggering this effect.

Hydrogen bonding in pyridine N-oxide/acid systems: proton transfer and fine details revealed by FTIR, NMR, and X-ray diffraction.

The H-bonded complexes of pyridine N-oxide (PyO) with H(2)O, acetic, cyanoacetic, propiolic, tribromoacetic, trichloroacetic, trifluoroacetic, hydrochloric, and methanesulfonic acids have been studied by FTIR and NMR spectroscopy, X-ray diffraction, and quantum chemical DFT calculations. Correlations between vibrational frequencies of the NO stretching and PyO ring modes and geometric parameters of the H-bond have been established. FTIR experiments show and DFT calculations confirm that definite discontinuity is present in the vicinity of the midpoint in the proton transfer pathway. The established correlations significantly aid in the understanding of fine effects such as the isotope (deuteration) effect, crystal-to-solution transition, or criticality of aqueous solutions induced by ionic pairs. Geometric isotope effect in the ionic H-bond aggregate of PyO·H(D)Cl was found to be extraordinary large. Measured FTIR, CP/MAS, and high-resolution (13)C NMR spectra indicate that H-bond in the PyO·HCl complex in polar solvent can potentially be more ionic than in the crystal. Vibrational modes of ionic pairs originating via proton transfer in H-bond complexes can provide new information concerning the interionic interaction and its role in the phase separation and mezo-structuring processes. The results are compared to the relevant data for PyO·HCl complex in argon matrix.

Interplay between defect structure and catalytic activity in the Mo(10-x)V(x)O(y) mixed-oxide system.

The Mo(10-x)V(x)O(y) solid-solution systems (0≤x≤10) were studied by electron paramagnetic resonance spectroscopy. The results show the existence of paramagnetic vanadyl VO(2+) species, whose concentration becomes maximal for Mo(5)V(5)O(y·). A quantitative analysis of the [VO(2+)] concentration as a function of the Mo/V ratio allows it to characterize the prevailing defect chemistry in the Mo(10-x)V(x)O(y) system. In this respect, the semi-conducting properties of Mo(10-x)V(x)O(y) are p-type in an interval of Mo(9)V(1)O(y)-Mo(5)V(5)O(y) and switch into n-type because of the conduction electrons in a composition range of Mo(5)V(5)O(y)-Mo(1)V(9)O(y). Highest catalytic activity is obtained when vanadium acts as an acceptor center and oxygen vacancies ν(··)(O) are formed for reasons of charge compensation. In addition to the surface, ν(··)(O) and VO(2+) centers in the bulk have to be considered too for heterogeneous catalysis.

N-Phenyl-succinamic acid.

In the crystal structure of the title compound, C(10)H(11)NO(3), the conformations of N-H and C=O bonds in the amide segment are anti to each other. Further, the conformations of the amide O atom and the carbonyl O atom of the acid segment are anti to each other and to the adjacent -CH(2) groups. The C=O and O-H bonds of the acid group are in syn positions with respect to each other. In the crystal, the mol-ecules are packed into infinite chains along the a axis through inter-molecular N-H⋯O and O-H⋯O hydrogen bonds.

1,8-Bis(3-chloro-anilino)-N,N'-bis-(3-chloro-phen-yl)octane-1,8-diimine.

There are two half-mol-ecules in the asymmetric unit of the title compound, C(32)H(30)Cl(4)N(4), in both of which the N-H bonds are syn to the meta-chloro substituents in the adjacent benzene ring. The other two Cl atoms of these two mol-ecules are disordered with occunpancy ratios of 0.79 (2):0.21 (2) and 0.68 (1):0.32 (1). Adjacent chloro-phenyl rings make dihedral angles of 74.3 (2) and 63.0 (2)° in the two mol-ecules. In the crystal, inter-molecular N-H⋯N hydrogen bonds link the mol-ecules into infinite chains.

Erratum: N,N'-Bis(phenyl-sulfon-yl)maleamide. Corrigendum.

The chemical name of the title compound in the paper by Gowda, Foro, Suchetan & Fuess [Acta Cryst. (2010), E66, o187] is corrected.[This corrects the article DOI: 10.1107/S1600536809053811.].

N-(2,3-Dimethyl-phen-yl)-2,4-dimethyl-benzene-sulfonamide.

The asymmetric unit of the title compound, C(16)H(19)NO(2)S, contains two independent mol-ecules: the dihedral angles between the sulfonyl and anilino benzene rings in the two mol-ecules are 41.5 (1) and 43.8 (1)°. The independent mol-ecules are linked into a dimer by a pair of inter-molecular N-H⋯O hydrogen bonds.

N-Benzoyl-2-methyl-benzene-sulfonamide.

In the title compound, C(14)H(13)NO(3)S, the conformation of the N-H bond in the C-SO(2)-NH-C(O) segment is anti to the C=O bond. The tolyl and benzoyl groups are twisted about the S-N bond, with a C-S-N-C torsion angle of 68.8 (4)°. The dihedral angle between the sulfonyl and the benzoyl benzene rings is 73.9 (1)°. In the crystal, the mol-ecules are linked into C(4) chains along the c axis by N-H⋯O hydrogen bonds.

N-Benzoyl-4-methyl-benzene-sulfonamide.

In the title compound, C(14)H(13)NO(3)S, the N-H bond in is anti to the C=O bond. The dihedral angle between the two aromatic rings is 79.4 (1)°. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, generating C(4) chains.

2-Chloro-N-(2-chloro-benzo-yl)benzene-sulfonamide.

In the structure of the title compound, C(13)H(9)Cl(2)NO(3)S, the N-H bond is anti to the C=O bond and the dihedral angle between the two aromatic rings is 76.9 (1)°. In the crystal structure, mol-ecules are linked by N-H⋯O(S) hydrogen bonds to form inversion dimers.

N-(2,4-Dimethyl-phen-yl)-2,4-dimethyl-benzene-sulfonamide.

In the crystal structure of the title compound, C(16)H(19)NO(2)S, the mol-ecule is bent at the S atom with a C-SO(2)-NH-C torsion angle of 66.5 (2)°. The dihedral angle between the sulfonyl and aniline benzene rings in the mol-ecule is 41.0 (1)°. The crystal structure features inversion dimers linked by pairs of N-H⋯O hydrogen bonds.

N-(3,5-Dichloro-phen-yl)-2,4-dimethyl-benzene-sulfonamide.

In the crystal structure of the title compound, C(14)H(13)Cl(2)NO(2)S, the conformation of the N-C bond in the C-SO(2)-NH-C segment has gauche torsions with respect to the S=O bonds. The mol-ecule is bent at the N atom, with an C-SO(2)-NH-C torsion angle of -54.9 (3)°. The two benzene rings are tilted relative to each other by 82.3 (2)°. The mol-ecules are linked into centrosymmetric R(2) (2)(8) motifs by N-H⋯O hydrogen bonds and C-H⋯π inter-actions along [100].

2,2,2-Tribromo-N-(3-chloro-phen-yl)acetamide.

In the title compound, C(8)H(5)Br(3)ClNO, the conformation of the N-H bond is anti to the 3-chloro substituent in the benzene ring. An intra-molecular N-H⋯Br hydrogen bond occurs. In the crystal, mol-ecules are packed into infinite chains in the a-axis direction by N-H⋯O hydrogen bonds.

N-(3,4-Dimethyl-phen-yl)-2,4-dimethyl-benzene-sulfonamide.

In the title compound, C(16)H(19)NO(2)S, the dihedral angle between the aromatic rings is 47.2 (2)°. The crystal structure features zigzag C(4) chains linked by N-H⋯O hydrogen bonds.

N-(2,6-Dimethyl-phen-yl)-4-methyl-benzene-sulfonamide.

In the title compound, C(15)H(17)NO(2)S, the mol-ecule is bent at the S atom, the C-SO(2)-NH-C torsion angle being 88.0 (2)°. The dihedral angle between the two aromatic rings is 49.8 (1)°. In the crystal, mol-ecules are linked into zigzag chains parallel to the a axis via N-H⋯O hydrogen bonds.

Methyl N-(2,3-dichloro-phen-yl)succinamate.

The asymmetric unit of the title compound, C(11)H(11)Cl(2)NO(3), contains two independent mol-ecules. In both the molecules, the H atoms of the adjacent -CH(2) groups of the acid segments orient themselves away from the amide O and the carbonyl O atoms. The C=O and O-CH(3) bonds of the ester group are in syn positions with respect to each other. In the crystal, the mol-ecules are linked into infinite chains through inter-molecular N-H⋯O hydrogen bonds.

4-Chloro-N-(3,4-dimethyl-phen-yl)benzamide.

In the title compound, C(15)H(14)ClNO, the N-H bond is trans to the C=O bond. The dihedral angle between the two aromatic rings is 5.5 (2)°. In the crystal, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into chains running along the a axis.

4-Chloro-N-(4-chloro-benzo-yl)benzene-sulfonamide.

In the title compound, C(13)H(9)Cl(2)NO(3)S, the conformation of the N-H bond in the C-SO(2)-NH-C(O) segment is anti to the C=O bond. The mol-ecule is twisted at the S atom with a torsion angle of 67.5 (3)°. The dihedral angle between the sulfonyl benzene ring and the -SO(2)-NH-C-O segment is 79.0 (1)° and that between the sulfonyl and benzoyl benzene rings is 85.6 (1)°. In the crystal, mol-ecules are linked by N-H⋯O(S) hydrogen bonds with graph-set descriptor C(4) along the [010] direction.

N-(3-Methyl-phen-yl)succinimide.

In the title compound, C(11)H(11)NO(2), the dihedral angle between the ring planes is 52.5 (1)°.

2-Chloro-N-(2-methyl-benzo-yl)benzene-sulfonamide.

In the title compound, C(14)H(12)ClNO(3)S, the N-H bond is anti-periplanar to the C=O bond. The dihedral angle between the two aromatic rings is 78.7 (1)°. The crystal structure features inversion-related dimers linked by pairs of N-H⋯O(S) hydrogen bonds.