4,6-Dinitro­pyrogallol

In the title mol­ecule, C6H4N2O7, the two nitro groups are tilted with respect to the aromatic ring by 11.2 (1) and 10.9 (1)°. All three hy­droxy groups are involved in the formation of bifurcated intra- and inter­molecular O—H⋯O hydrogen bonds. The crystal packing exhibits short O⋯O distances of 2.823 (2) Å between two O atoms of the nitro groups

Tris(cis-2-hy­droxy­cyclo­hexane-1,3,5-tri­aminium) hydrogen sulfate octa­chloride dihydrate

The 2-hy­droxy­cyclo­hexane-1,3,5-triaminium (= H3 L 3+) cation of the title compound, 3C6H18N3O3+·8Cl−·HSO4 −·2H2O, exhibits a cyclo­hexane chair with three equatorial ammonium groups and one axial hy­droxy group in an all-cis configuration. The hydrogen sulfate anion and two water mol­ecules lie on or in proximity to a threefold axis and are disordered. The crystal structure features N—H⋯Cl and O—H⋯Cl hydrogen bonds. Three C 3-symmetric motifs can be identified in the structure: (i) Two chloride ions (on the C 3-axis) together with three H3 L 3+ cations constitute an [(H3 L)3Cl2]7+ cage. (ii) The lipophilic C6H6-sides of three H3 L 3+ cations, which are oriented directly towards the C 3-axis, generate a lipophilic void. The void is filled with the disordered water mol­ecules and with the disordered part of the hydrogen sulfate ion. The hydrogen atoms of these disordered moieties were not located. (iii) Three H3 L 3+ cations together with one HSO4 − and three Cl− counter-ions form an [(HSO4)(H3 L)3Cl3]5+ cage. Looking along the C 3-axis, these three motifs are arranged in the order (cage 1)⋯(lipophilic void)⋯(cage 2). The crystal studied was found to be a racemic twin

fac-{2-[Bis(2-amino­eth­yl)amino]­ethanaminium}trichloridorhodium(III) chloride hemihydrate

The crystal structure of the title compound, [Rh(C6H19N4)Cl3]Cl·0.5H2O, is isotypic with the previously reported Ru analogue. The structure contains two crystallographically independent [Rh(Htren)Cl3]+ cations with a facial tridentate coordination of the monoprotonated tren ligand [tren = tris­(2-amino­eth­yl)amine], leading to an overall distorted octahedral coordination environment around the Rh(III) atom. In one of the two cations, the ethyl­ene groups of the two chelate rings as well as the non-coordinating ethyl­ammonium group are disordered over two sets of sites [0.579 (3):0.421 (3) occupancy ratio]. A series of N—H⋯Cl and O—H⋯Cl hydrogen bonds stabilizes the structure

The coordination chemistry of pyridylmethyl derivatives of 1,4-diazepan-6-amine

Ausgehend von 1,4-Diazepan-6-amin (daza), 6-Methyl-1,4-diazepan-6-amin (aaz) und cis-3,5-Diaminopiperidin (cis-dapi) wurde durch reduktive Alkylierung eine Reihe von Pyridylmethylderivaten dieser cyclischen Triamine hergestellt. In potentiometrischen und spektrophotometrischen Titrationen wurden die Stabilitätskonstanten der 4- bis 6-zähnigen Liganden mit den Übergangsmetallen Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ und Cd2+ bestimmt. Dabei zeichneten sich die durch die Pyridylmethylgruppen azidifierten Liganden durch hohe Komplexstabilitäten vor allem im sauren pH-Bereich aus. Je nach Substitutionsgrad unterscheiden sich die Derivate in ihrer Selektivität bezüglich einer Komplexierung von Cu2+ und Ni2+. In Festkörperstrukturen der Komplexe mit Fe3+, Co3+, Ni2+ und Cd2+ konnte Koordinationszahl 6 mit Koordinationspolyedern zwischen einer oktaedrischen und trigonal-prismatischen Geometrie nachgewiesen werden. Dagegen fand man für Komplexe mit Cu2+ und Zn2+ Koordinationszahl 5 mit Polyedergeometrien zwischen einer trigonalen Bipyramide und einer tetragonalen Pyramide. UV/Vis-spektroskopische Untersuchungen zeigten, dass die Pyridylmethylderivate von daza ein vergleichsweise schwaches Ligandenfeld besitzen. Cyclovoltammetrische Messungen an Mn-, Fe- und Co-Komplexen belegten die Pi-Akzeptorfähigkeit der Chelatoren. Obwohl die Liganden zur Bildung von [LFe(III)(OOH)]-Komplexen befähigt sind, ist deren katalytische Aktivität zur Oxidation von Cycloocten nur gering ausgeprägt.A number of pyridylmethyl derivatives of the cyclic triamines 1,4-diazepan-6-amine (daza), 6-methyl-1,4-diazepan-6-amine (aaz) and cis-3,5-diaminopiperidine (cis-dapi) has been prepared by reductive alkylation. The stability constants of the tetra-, penta- and hexadentate ligands with the divalent transition metals Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ and Cd2+ were determined by means of potentiometric and spectrophotometric titrations. All derivatives which are acidified by their pyridylmethyl-pendant arms revealed high complex stabilities especially in acidic solution. Depending on the degree of substitution the ligands show different selectivity for the metals Cu2+ and Ni2+. Solid state structures of complexes with Fe3+, Co3+, Ni2+ and Cd2+ exhibited co-ordination number 6 with distorted octahedral or trigonal prismatic coordination poly-hedra. In contrast, in the crystal structures of complex species with Cu2+ and Zn2+ coordination number 5 with a geometry in-between a trigonal bipyramidal and a square pyramidal arrangement was found. As shown by UV/Vis spectrophotometric measurements the pyridylmethyl derivatives of daza evoke only a weak ligand field compared to related ligands. Cyclovoltammetric studies of complexes with Mn, Fe and Co established the pi-acceptor capability of the chelators. Although the ligands are capable of forming [LFe(III)(OOH)]-species, their catalytic activity in oxidation reactions with cycloocten was only minor characteristic

The coordination chemistry of pyridylmethyl derivatives of 1,4-diazepan-6-amine

Ausgehend von 1,4-Diazepan-6-amin (daza), 6-Methyl-1,4-diazepan-6-amin (aaz) und cis-3,5-Diaminopiperidin (cis-dapi) wurde durch reduktive Alkylierung eine Reihe von Pyridylmethylderivaten dieser cyclischen Triamine hergestellt. In potentiometrischen und spektrophotometrischen Titrationen wurden die Stabilitätskonstanten der 4- bis 6-zähnigen Liganden mit den Übergangsmetallen Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ und Cd2+ bestimmt. Dabei zeichneten sich die durch die Pyridylmethylgruppen azidifierten Liganden durch hohe Komplexstabilitäten vor allem im sauren pH-Bereich aus. Je nach Substitutionsgrad unterscheiden sich die Derivate in ihrer Selektivität bezüglich einer Komplexierung von Cu2+ und Ni2+. In Festkörperstrukturen der Komplexe mit Fe3+, Co3+, Ni2+ und Cd2+ konnte Koordinationszahl 6 mit Koordinationspolyedern zwischen einer oktaedrischen und trigonal-prismatischen Geometrie nachgewiesen werden. Dagegen fand man für Komplexe mit Cu2+ und Zn2+ Koordinationszahl 5 mit Polyedergeometrien zwischen einer trigonalen Bipyramide und einer tetragonalen Pyramide. UV/Vis-spektroskopische Untersuchungen zeigten, dass die Pyridylmethylderivate von daza ein vergleichsweise schwaches Ligandenfeld besitzen. Cyclovoltammetrische Messungen an Mn-, Fe- und Co-Komplexen belegten die Pi-Akzeptorfähigkeit der Chelatoren. Obwohl die Liganden zur Bildung von [LFe(III)(OOH)]-Komplexen befähigt sind, ist deren katalytische Aktivität zur Oxidation von Cycloocten nur gering ausgeprägt.A number of pyridylmethyl derivatives of the cyclic triamines 1,4-diazepan-6-amine (daza), 6-methyl-1,4-diazepan-6-amine (aaz) and cis-3,5-diaminopiperidine (cis-dapi) has been prepared by reductive alkylation. The stability constants of the tetra-, penta- and hexadentate ligands with the divalent transition metals Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ and Cd2+ were determined by means of potentiometric and spectrophotometric titrations. All derivatives which are acidified by their pyridylmethyl-pendant arms revealed high complex stabilities especially in acidic solution. Depending on the degree of substitution the ligands show different selectivity for the metals Cu2+ and Ni2+. Solid state structures of complexes with Fe3+, Co3+, Ni2+ and Cd2+ exhibited co-ordination number 6 with distorted octahedral or trigonal prismatic coordination poly-hedra. In contrast, in the crystal structures of complex species with Cu2+ and Zn2+ coordination number 5 with a geometry in-between a trigonal bipyramidal and a square pyramidal arrangement was found. As shown by UV/Vis spectrophotometric measurements the pyridylmethyl derivatives of daza evoke only a weak ligand field compared to related ligands. Cyclovoltammetric studies of complexes with Mn, Fe and Co established the pi-acceptor capability of the chelators. Although the ligands are capable of forming [LFe(III)(OOH)]-species, their catalytic activity in oxidation reactions with cycloocten was only minor characteristic

1,2,3-Trimethoxy-4,5,6-trinitrobenzene

In the title molecule, C9H9N3O9, the three neighbouring nitro groups are tilted with respect to the benzene mean plane by 75.8 (1), 27.7 (1) and 68.1 (1)°. The methyl C atoms of the three neighbouring methoxy groups deviate from this plane by 0.976 (4), −1.425 (4) and 0.632 (4) Å. The crystal packing exhibits weak C—H...O interactions

1,3-Diammonio-1,2,3-trideoxy-cis-inositol sulfate

In the crystal structure of the title compound, C6H16N2O32+·SO42−, each cation forms three O—H...O and five N—H...O hydrogen bonds to six neighbouring sulfate anions. In addition, interlinking of the cations by N—H...O interactions is also observed. The cyclohexane ring adopts a chair conformation with two axial hydroxy groups. Although the separation of 2.928 Å is almost ideal for a hydrogen bond, intramolecular hydrogen bonding between these two hydroxy groups is not observed

(S)-2,2′-Dihydroxy-N,N′-(6-hydroxyhexane-1,5-diyl)dibenzamide

In the title compound, C20H24N2O5, the dihedral angle between the two roughly planar salicylamide fragments [r.m.s. deviations = 0.043 (2) and 0.149 (2) Å] is 25.50 (5)°. The molecular conformation is stabilized by intramolecular O—H...O hydrogen bonds involving phenol –OH groups and amide O atoms. Intermolecular hydroxymethyl–amide O—H...O and amine–hydroxymethyl N—H...O hydrogen bonds form infinite chains along the b axis. These chains are further interlinked by amine–amide N—H...O and phenol–phenol O—H...O interactions, thus giving layers parallel to (001)