Takeo Fukunaga

Piperidinium hydrogen chloranilate

In the title compound, C5H10NH2+·C6HO4Cl2−, two chloranilate ions are connected by O—H⋯O hydrogen bonds to form a dimeric unit. The piperidinium ions are linked on both sides of the dimer via a bifurcated N—H⋯O hydrogen bond to afford a 2:2 complex of chloranilic acid and piperidine. The 2:2 complexes are linked together to form a hydrogen-bonded molecular tape.

Crystal Structure and Cationic Motion of o-Toluidinium Chloranilate and m-Toluidinium Chloranilate Studied by X-ray Diffraction and 1H NMR

The crystal structure of o-toluidinium chloranilate and m-toluidinium chloranilate, 2CH3C6H4-NH3+ · C6O4Cl22−, was determined by single crystal X-ray diffraction at room temperature. It was found that o-toluidinium chloranilate (I) is monoclinic, P21/n (#14), Z = 2, a = 5.2184(14), b = 7.825(2), c = 22.840(5) Å , and β = 92.015(19)°, and m-toluidinium chloranilate (II) is monoclinic, P21/c (#14), Z = 2, a = 11.214(2), b = 5.4844(10), c = 16.379(6) Å, and β = 105.21(2)°. In these salts, the cations are connected with the anions by N-H... O hydrogen bonds to form 2:1 units of 2CH3C6H4NH3+ · C6O4Cl22− that are located on inversion centers. The 2CH3C6H4NH3+ · C6O4Cl22− units in both salts are connected by other N-H... O hydrogen bonds to build a three-dimensional hydrogen-bond network. Motions of the toluidinium ions in solid (I) and (II) were studied by 1H NMR spin-lattice relaxation time measurements. Reorientations of the NH3+ group about the C-N bond axis and the CH3 group about the C-C bond axis were observed, and their motional parameters were evaluated. The internal rotational barriers of the NH3+ and CH3 groups of an isolated o-toluidinium ion were estimated from ab initio molecular orbital calculations at HF/6-31G(d,p), MP2/6-31G(d,p), and B3LYP/6-31G(d,p) levels of theory.

The 1:1 complex of 4-chloro-3-nitro­benzoic acid and pyridazine

In the title compound, C7H4ClNO4·C4H4N2, the two components are connected by an O—H⋯N hydrogen bond. C—H⋯O hydrogen bonds connect the C7H4ClNO4·C4H4N2 units to afford a macrocycle with graph-set descriptor R44(16); this ring is located on an inversion center.

2-Pyridone-tartronic acid (1/1), 3-hydroxypyridinium hydrogen tartronate and 4-hydroxypyridinium hydrogen tartronate.

Tartronic acid forms a hydrogen-bonded complex, C 5 H 5 NO.-C 3 H 4 O 5 , (I), with 2-pyridone, while it forms acid salts, namely 3-hydroxypyridinium hydrogen tartronate, (II), and 4-hydroxypyridinium hydrogen tartronate, (III), both C 5 H 6 NO + .-C 3 H 3 O 5 - , with 3-hydroxypyridine and 4-hydroxypyridine, respectively. In (I), the pyridone molecules and the acid molecules form R 2 2 (8) and R 2 2 (10) hydrogen-bonded rings, respectively, around the inversion centres. In (II) and (III), the cations and anions are linked by N-H...O and O-H...O hydrogen bonds to form a hydrogen-bonded chain. In each of (I), (II) and (III), an intermolecular hydrogen bond is formed between a carboxyl group and the hydroxyl group attached to the central C atom, and in (I), the hydroxyl group participates in an intramolecular hydrogen bond with a carbonyl group. No intermolecular hydrogen bond is formed between the carboxyl groups in (I), or between the carboxyl and carboxylate groups in (II) and (III).

The 1:1 Complex of 2-Chloro-4-nitrobenzoic Acid and 1,2,3-Benzotriazole

In the title compound, C7H4ClNO4·C6H5N3, two acid and two base components are connected by O—H⋯N and N—H⋯O hydrogen bonds to afford a centrosymmetric macrocycle with graph-set descriptor R44(16). C—H⋯O hydrogen bonds connect the ring units to form a ribbon structure.

Ammonium hydrogen tartronate at 240 and 20 K

The low-temperature structure determination of the title compound, alternatively called ammonium hydrogen hydroxypropanedioate, NH(4)(+) x C(3)H(3)O(5)(-), has revealed that the H atom involved in a very short asymmetric O--H...O hydrogen bond [O...O = 2.448 (2) A at 240 K and 2.4393 (10) A at 20 K] is disordered.

Benzimidazolium 2-chloro-4-nitro­benzoate

In the title compound, C7H7N2+·C7H3ClNO4−, the cations and anions are connected by N—H⋯O hydrogen bonds to afford a 21 helical chain.

A new polymorph of barium chloro­anilate trihydrate

Single crystals of a new polymorph of the title compound, barium(II) 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone trihydrate, Ba2+.C6Cl2O4(2-).3H2O, have been grown in sodium metasilicate gel. Each Ba2+ cation is coordinated by eight O atoms. The Ba2+ cations are bridged by an O atom of a ligand around the centre of symmetry at Wyckoff position 4a and by the O atom of a water molecule around the centre of symmetry at Wyckoff position 4b, forming a sheet parallel to the (100) plane. Loose contacts are found around one of the water molecules, as observed in the Cmca form.

Potassium hydrogen trans-glutaconate monohydrate at 295, 245 and 40 K, and its rubidium analogue at 298 K

A centrosymmetric and short O-H.O hydrogen bond was found in isomorphic crystals of potassium hydrogen trans-glutaconate monohydrate (potassium hydrogen trans-pent-2-ene-1,5-dioate, K(+).C(5)H(5)O(4)(-).H(2)O), (I), and rubidium hydrogen trans-glutaconate monohydrate (rubidium hydrogen trans-pent-2-ene-1,5-dioate, Rb(+).C(5)H(5)O(4)(-).H(2)O), (II). The O.O distance at room temperature is 2.444 (3) A in (I), and 2.417 (4) A in (II). The O.O distance for (I) showed no significant decrease at low temperatures.

Hydrogen-bonded complexes of 2-pyridone with centrosymmetric and non-centrosymmetric dicarboxylic acids

2-Pyridone (2-oxopyrimidine) forms hydrogen-bonded complexes with dicarboxylic acids, the molar ratio of 2-pyridone/dicarboxylic acid being 2:1 for the complexes with oxalic acid (ethanedioic acid), 2C(5)H(5)NO.C(2)H(2)O(4), (I), and trans-beta-hydromuconic acid (trans-hex-3-enedioic acid), 2C(5)H(5)NO.C(6)H(8)O(4), (II), and 1:1 for the complexes with trans-glutaconic acid (trans-pent-2-enedioic acid), C(5)H(5)NO.C(5)H(6)O(4), (III), and L-tartaric acid (L-2,3-dihydroxybutanedioic acid), C(5)H(5)NO.C(4)H(6)O(6).H(2)O, (IV). Common features in the hydrogen-bonding patterns were found for the centrosymmetric and non-centrosymmetric acids, respectively. The 2-pyridone molecule takes the lactam form in these crystals.