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In the binuclear title complex, [La2(C2H3O2)4(C11H10N4)(H2O)4](NO3)2·0.5H2O, the two lanthanum ions are nine coordinate in a distorted trigonal–prismatic geometry. Each LaIII ion is bonded to three N atoms of the Schiff base, 1-(pyridin-2-yl)-2-(pyridin-2-ylmethylene)hydrazine and is coordinated by one acetate group, which acts in η2-bidentate mode and two acetate groups that act in μ2-mode between the two LaIII ions. Two η1-water molecules complete the coordination sphere. All bond lengths in the coordination environment of the LaIII ion are slightly larger than those observed in the isostructural NdIII and SmIII complexes. The LaIII...LaIII distance is 4.6696 (6) Å. In the crystal, extensive O—H...O hydrogen-bonding interactions involving the coordinated water molecules and the non-coordinating nitrate anions, as well as the oxygen atoms of the acetate groups, generate an overall three-dimensional supramolecular network.

The chemical reaction of 4-bromobenzoylchloride and 2-aminothiazole in the presence of potassium thiocyanate yielded a white solid formulated as C15H10BrN3OS2, which consists of 4-bromobenzamido and 2-benzothiazolyl moieties connected by a thiourea group. The 4-bromobenzamido and 2-benzothiazolyl moieties are in a trans conformtion (sometimes also called s-trans due to the single bond) with respect to the N—C bond. The dihedral angle between the mean planes of the 4-bromophenyl and the 2-benzothiazolyl units is 10.45 (11)°. The thiourea moiety, —C—NH—C(=S) —NH— fragment forms a dihedral angle of 8.64 (12)° with the 4-bromophenyl ring and is almost coplanar with the 2-benzothiazolyl moiety, with a dihedral angle of 1.94 (11)°. The molecular structure is stabilized by intramolecular N—H...O hydrogen bonds, resulting in the formation of an S(6) ring. In the crystal, pairs of adjacent molecules interact via intermolecular hydrogen bonds of type C—H...N, C—H...S and N—H...S, resulting in molecular layers parallel to the ac plane.

The reaction of the Schiff base 2-[1-(pyridin-2-yl)ethylideneamino]ethanol (HL), which is formed by reaction of 2-aminoethanol and 2-acetylpyridine with CuBr2 in ethanol results in the isolation of the new polymeric complex poly[hexa-μ-bromido-bis{2-[1-(pyridin-2-yl)ethylideneamino]ethanolato}tetracopper(II)], [Cu4Br6(C9H11N2O)2]n or [Cu4Br6L2]n. The asymmetric unit of the crystal structure of the polymeric [Cu4Br6L2]n complex is composed by four copper (II) cations, two monodeprotonated molecules of the ligand, and six bromide anions, which act as bridges. The ligand molecules act in a tridentate fashion through their azomethine nitrogen atoms, their pyridine nitrogen atoms, and their alcoholate O atoms. The crystal structure shows two types of geometries in the coordination polyhedrons around Cu2+ ions. Two copper cations are situated in a square-based pyramidal environment, while the two other copper cations adopt a tetrahedral geometry. Bromides anions acting as bridges between two metal ions connect the units, resulting in a tetranuclear polymer compound.

We report the synthesis and structures of two transition-metal complexes involving 2-(2-hydroxyphenyl)benzimidazole (2hpbi – a ligand of interest for its photoluminescent applications), with cobalt, namely, bis[μ-2-(1H-1,3-benzodiazol-2-yl)phenolato]bis[ethanol(thiocyanato)cobalt(II)], [Co2(C13H9N2O)2(NCS)2(C2H6O)2], (1), and manganese, namely, bis[μ-2-(1H-1,3-benzodiazol-2-yl)phenolato]bis{[2-(1H-1,3-benzodiazol-2-yl)phenolato](thiocyanato)manganese(III)} dihydrate, [Mn2(C13H9N2O)4(NCS)2]·2H2O, (2). These structures are two recent examples of a fruitful collaboration between researchers at the Laboratoire de Chimie de Coordination Organique/Organic Coordination Chemistry Laboratory (LCCO), University of Dakar, Senegal and the National Crystallography Service (NCS), School of Chemistry, University Southampton, UK. This productive partnership was forged through meeting at Pan-African Conferences on Crystallography and quickly grew as the plans for the AfCA (African Crystallographic Association) developed. This article therefore also showcases this productive partnership, in celebration of the IUCr's 75 year anniversary and the recent inclusion of AfCA as a Regional Associate of the IUCr.

Two new heterocyclic 1,2,3-triazenes were synthesized by diazotation of 3-aminopyridine following respectively by coupling with morpholine or 1,2,3,4-tetrahydroquinoline. 4-[(Pyridin-3-yl)diazenyl]morpholine (I), C9H12N4O, has monoclinic P21/c symmetry at 100 K, while 1-[(pyridin-3-yl)diazenyl]-1,2,3,4-tetrahydroquinoline (II), C14H14N4, has monoclinic P21/n symmetry at 100 K. These 1,2,3-triazene derivatives were synthesized by the organic medium method by coupling reactions of 3-aminopyridine with morpholine and 1,2,3,4-tetrahydroquinoline, respectively, and characterized by 1H NMR, 13C NMR, IR, mass spectrometry, and single-crystal X-ray diffraction. The molecule of compound I consists of pyridine and morpholine rings connected by an azo moiety (–N=N–). In the molecule of II, the pyridine ring and the 1,2,3,4-tetrahydroquinoline unit are also connected by an azo moiety. The double- and single-bond distances in the triazene chain are comparable for the two compounds. In both crystal structures, the molecules are connected by C—H...N interactions, forming infinite chains for I and layers parallel to the bc plane for II.

This article reports a practical synthesis of tert-butyl acetylcarbamate, C7H13NO3, from N-Boc-thioacetamide and the study of its crystal structure. The reaction proceeds in the presence of natural phosphate as a catalyst, with excellent yield, simple workup and benign environment. The crystal structure was refined using a transferred multipolar atom model. In the crystal, symmetrical pairs of strong N—H...O hydrogen bonds connect the molecules into dimers with an R22(8) ring motif. The interactions between neighbouring dimers are mostly van der Waals, between hydrophobic methyl groups. Hirshfeld surface analysis shows the major contributions to the crystal packing are from H...H (42.6%) and O...H (26.7%) contacts.

The title molecular structure, namely, (μ3-acetato)(μ2-acetato)bis(μ3-1,3-bis{[1-(2-oxidophenyl)ethylidene]amino}propan-2-olato)tetracopper(II) monohydrate, [Cu4(C19H19N2O3)2(CH3CO2)2]·H2O, corresponds to a non-symmetric tetranuclear copper complex. The complex exhibits one ligand molecule that connects two copper CuII metal centres via its ethanolato oxygen anion acting in a μ2-mode and one ligand molecule that connects three copper CuII metal centres via its ethanolato oxygen anion acting in a μ3-mode. One bridging acetate group acting in an η1:η1-μ2-mode connects two copper(II) ions while another bridging acetate group connects three copper(II) ions in an η1:-η2-μ3-mode. A chair-like Cu3O3 structure is generated in which the two CuO4N units are connected by one μ2-O ethanolate oxygen atom. These two units are connected respectively to the CuO3N unit via one μ3-O ethanolate oxygen atom and one μ2-O atom from an acetate group. The μ3-O atom also connects one of the CuO4N units and the CuO3N unit to another CuO3N unit, which is out of the chair-like structure. Each of the two pentacoordinated CuII cations has a distorted NO4 square-pyramidal environment. The geometry of each of the two CuNO3 units is best described as a slightly square-planar environment. A series of intramolecular O—H...O hydrogen bonds is observed. In the crystal, the units are connected by intermolecular C—H...O and O—H...O hydrogen bonds, thus forming sheets parallel to the ac plane

The title molecular structure, namely, diaquatris(μ3-1,3-bis{[1-(2-oxidophenyl)ethylidene]amino}propan-2-olato)-μ3-hydroxido-dinitratohexacopper(II) ethanol trisolvate, [Cu6(C19H19N2O3)3(NO3)2(OH)(H2O)2]·3C2H5OH, corresponds to a non-symmetric hexanuclear copper complex. The complex exhibits one core in which three CuII metal centres are mutually interconnected, two by two, via three phenolato oxygen anions acting in a μ2-mode. These three copper cations are interconnected in a μ3-mode by one hydroxyl group. An open-cube structure is generated in which each of the CuII cations of the three CuO4N units is connected by two μ2-O anions from phenolate groups and one μ3-O atom from a hydroxy anion. Each of the three pentacoordinated CuII cations situated in the open-cube unit has a distorted NO4 square-pyramidal environment. Each of these three CuII centres is interconnected with another CuII cation via one enolate O atom in μ2-mode, yielding one CuNO4 unit and two CuNO3 units. The pentacoordinated CuII atom has a distorted square-pyramidal environment while the two tetracoordinated copper(II) cations are situated in a square-planar environment. A series of intramolecular O—H...O hydrogen bonds are observed. In the crystal, the units are connected two by two by intermolecular C—H...O and O—H...O hydrogen bonds, thus forming sheets parallel to the ac plane.

A tetranuclear ZnII complex, [Zn4(C13H11N6O)2Cl6(H2O)2] or {[Zn2(HL)(H2O)(Cl2)](μCl)2[Zn2(HL)(H2O)(Cl)]}2, was synthesized by mixing an equimolar amount of a methanol solution containing ZnCl2 and a methanol solution containing the ligand H2L [1,5-bis(pyridin-2-ylmethylene)carbonohydrazide]. In the tetranuclear complex, each of the two ligand molecules forms a dinuclear unit that is connected to another dinuclear unit by two bridging chloride anions. In each dinuclear unit, one ZnII cation is pentacoordinated in a N2OCl2 in a distorted square-pyramidal geometry, while the other ZnII cation is hexacoordinated in a N3OCl2 environment with a distorted octahedral geometry. The basal plane around the pentacoordinated ZnII cation is formed by one chloride anion, one oxygen atom, one imino nitrogen atom and one pyridine nitrogen atom with the apical position occupied by a chloride anion. The basal plane of the hexacoordinated ZnII cation is formed by one chloride anion, one hydrazinyl nitrogen atom, one imino nitrogen atom and one pyridine nitrogen atom with the apical positions occupied by a water oxygen atom and a bridged chloro anion from another dinuclear unit, leading to a tetranuclear complex. A series of intramolecular C—H...Cl hydrogen bonds is observed in each tetranuclear unit. In the crystal, the tetranuclear units are connected by intermolecular C—H...Cl, C—H...O and N—H...O hydrogen bonds, forming a planar two-dimensional structure in the ac plane.

The condensation of 2-furoic hydrazide and 4-dimethyl aminobenzaldehyde in ethanol yielded a yellow solid formulated as the title compound, C14H15N3O2·H2O. The crystal packing is stabilized by intermolecular O(water)—H...O,N(carbohydrazide) and N—H...O(water) hydrogen bonds, which form a two-dimensional network along the bc plane. Additional C—H...O interactions link the molecules into a three-dimensional network. The dihedral angle between the mean planes of the benzene and the furan ring is 34.47 (6)°. The carbohydrazide moiety, i.e., the C=N—N—C=O fragment and the benzene ring are almost coplanar, with an angle of 6.75 (9)° between their mean planes.

Two CuII complexes [Cu(C14H13N4O2)Cl]n, I, and [Cu4(C8H10NO2)4Cl4]n, II, have been synthesized. In the structure of the mononuclear complex I, each ligand is coordinated to two metal centers. The basal plane around the CuII cation is formed by one chloride anion, one oxygen atom, one imino and one pyridine nitrogen atom. The apical position of the distorted square-pyramidal geometry is occupied by a pyridine nitrogen atom from a neighbouring unit, leading to infinite one-dimensional polymeric chains along the b-axis direction. Each chain is connected to adjacent chains by intermolecular C—H...O and C—H...Cl interactions, leading to a three-dimensional network structure. The tetranuclear complex II lies about a crystallographic inversion centre and has one core in which two CuII metal centers are mutually interconnected via two enolato oxygen atoms while the other two CuII cations are linked by a chloride anion and an enolato oxygen. An open-cube structure is generated in which the two open-cube units, with seven vertices each, share a side composed of two CuII ions bridged by two enolato oxygen atoms acting in a μ3-mode. The CuII atoms in each of the two CuO3NCl units are connected by one μ2-O and two μ3-O atoms from deprotonated hydroxyl groups and one chloride anion to the three other CuII centres. Each of the pentacoordinated CuII cations has a distorted NO3Cl square-pyramidal environment. The CuII atoms in each of the two CuO2NCl2 units are connected by μ2-O and μ3-O atoms from deprotonated alcohol hydroxy groups and one chloride anion to two other CuII ions. Each of the pentacoordinated CuII cations has a distorted NO2Cl2 square-pyramidal environment. In the crystal, a series of intramolecular C—H...O and C—H...Cl hydrogen bonds are observed in each tetranuclear monomeric unit, which is connected to four tetranuclear monomeric units by intermolecular C—H...O hydrogen bonds, thus forming a planar two-dimensional structure in the (\overline{1}01) plane.

The reaction of benzoyl chloride and ethylendiamine in the presence of potassium thiocyanate yielded a white solid, C18H18N4O2S2, which consists of two benzoylthioureido moieties connected by an ethylene chain. The asymmetric unit consists of one half of the molecule, the complete molecule being generated by crystallographic inversion symmetry. Both thiourea moieties are in a trans conformation. An intramolecular N—H...O hydrogen bond occurs. In the crystal, C—H...S and C—H...O hydrogen bonds link the molecules, forming layers parallel to the ac plane.

In the pentanuclear title complex, [SmZn2(C22H18N2O4)2(NCS)2(C3H7NO)2][Zn2(C22H18N2O4)(NCS)3]·C3H7NO·0.32H2O, namely bis{μ2-6,6′-dimethoxy-2,2′-[phenylene-1,2-diylbis(nitrilomethanylylidene)]diphenolato}-1κ4O,N,N′,O′:2κ3O,O′,O6;2κ3O,O′,O6:3κ4O,N,N′,O′-bis(dimethylformamide-2κO)dithiocyanato-1κN,3κN-2-samarium(III)-1,3-dizinc(II) {μ2-6,6′-dimethoxy-2,2′-[phenylene-1,2-diylbis(nitrilomethanylylidene)]diphenolato-1κ4O,N,N′,O′:2κ2O,O′}trithiocyanato-1κN;2κ2N,N-dizinc(II) dimethylformamide monosolvate 1.32-hydrate, a dinuclear unit and a trinuclear unit co-exist. One of the ZnII centers in the dinuclear unit as well as the two ZnII centers in the trinuclear unit are located in the inner N2O2 cavity of the ligand and are coordinated to the nitrogen atom of one thiocyanate moiety, giving rise to a square-pyramidal geometry. The second ZnII center in the dinuclear unit is coordinated to the two phenolate oxygen atoms of the ligand and to two thiocyanate groups via the nitrogen atom in a tetrahedral geometry. The SmIII ion is eight-coordinated by four phenolate O atoms from the two ligand molecules, two methoxy O atoms from the two ligand molecules and two O atoms from the DFM solvent molecule. In the dinuclear unit, the two methoxy oxygen atoms remain uncoordinated while in the trinuclear unit, for each ligand one methoxy oxygen is coordinated and the other one remains uncoordinated. In the crystal, the trinuclear cationic units and dinuclear anionic units are assembled into infinite layers. These layers are held together via electrostatic interactions, forming a three-dimensional structure. In the dinuclear unit, the C and S atoms of one of the thiocyanate groups are disordered over two sets of sites in a 0.680 (4)(4):0.320 (4) ratio.

The binuclear complex, [Sn2(C4H9)4(C16H10N4O4)], contains two Sn4+ ions, connected by doubly N-deprotonated oxalylbis[(2-oxidobenzylidene)hydrazide] ligands, and each Sn4+ ion is linked to two tert-butyl groups. The coordination sphere of each Sn atom is best described as a distorted trigonal bipyramid. Each stannic ion in the complex is in a C2O2N environment. The two homologous parts of the doubly deprotonated ligand are located in trans positions with respect to the C—C bond of the oxalamide group. The oxalamide group exhibits an asymmetric coordination geometry, as seen by the slight difference between the C—O and C—N bond lengths. The three-dimensional network is a multilayer of complex molecules with no strong supramolecular interactions.

The search for novel manganese(II) compounds having interesting magnetic properties, using 1-(pyridin-2-yl)-2-(pyridin-2-ylmethylidene)hydrazine (HL) as a tridendate ligand, led to the preparation of the title mononuclear material, [MnCl(NO3)(C11H10N4)(H2O)], and the determination of its structure by XRD. The asymmetric unit comprises a discrete molecule in which the cation MnII is heptacoordinated. The environment around the cation is an almost perfect pentagonal bipyramid. The base is defined by the two N atoms of the pyridine rings, the N atom of the imino function of the ligand and the two O atoms of the chelating bidentate nitrate ligand. The apical positions are occupied by a Cl atom and a water molecule. In the crystal, there are numerous hydrogen bonds of the types Ow—H...ONO2 and C—H...ONO2, which generate layers parallel to the bc plane in which the ligands in the axial positions point into the interlayer space. These axial ligands give rise to hydrogen bonds of the types Ow—H...ONO2, Ow—H...Cl, N—H...Cl and C—H...Cl, leading to a three-dimensional framework. The chain bridging the two pyridine rings is disordered over two sets of sites in a 0.53 (2):0.47 (2) ratio.

The title compound, C21H36O3, contains an oxolane ring, and six defined stereocentres and may serve as a useful synthon for the synthesis of calcitriol analogues. The configurations of the chiral C atoms of the side chain were unambiguously established in the refinement. In the crystal, C—H...O and extremely weak O—H...O hydrogen bonds arising from the sterically hindered alcohol group link the molecules into a three-dimensional network.

This article outlines the reactions of the well known [RuCl(η6-p-cymene)]2(μ-η4-C2O4) and [RuCl(η6-p-cymene)(η2-dppm)][PF6] ruthenium complexes with C2O4 (Me4N) 2 in the mol ratios 1:1 and 2:1. While the 2:1 ratio reaction led to the sole and expected binuclear product {[Ru(η6-p-cymene)(η2-dppm)]2(μ-η2-C2O4)}[PF6]2, the reaction also afforded the unexpected mononuclear complex [RuCl(η2-C2O4)(η6-p-cymene)][Me4N]. This can also be obtained in improved yield by reacting [RuCl2(p-cymene)] 2 with C2O4[Me4N] 2 in a 1:1 mol ratio. Surprisingly, when [RuCl(η6-p-cymene)]2(μ-η4-C2O4) was reacted with an equimolar amount of the ligand dppm, the expected complex {[Ru(η6-p-cymene)]2(μ-η4-C2O4)(μ-dppm)}[PF6]2 was accompanied by [RuCl(η6-p-cymene)(η2-dppm)][PF6] in an inseparable solid mixture.

Reaction of the 2,6-diformyl-4-chlorophenol-bis-(2'-hydroxy-benzoylhydrazone) with Ln(NO3)3.nH2O (n = 5 or 6 and Ln = Y, La, Ce, Pr, Nd, Sm, Gd, Dy, Er and Yb) produces homobinuclear complexes. These complexes have been characterized by analysis, molar conductance, magnetic measurements, infrared spectral studies and X-ray diffraction. The analytical data showed 1:3 (metal:ligand) stoichiometry. Molar conductance measurements in dmf indicate 1:3 electrolytes in all cases. Magnetic moment values are close proximity of the Van Vleck values. IR studies suggest the coordination of the ligand is through the azomethine, the phenolic oxygen atom and the carbonyl oxygen of the hydrazonic moiety. The nitrate ion is also found to be ionic in all the complexes. An X-ray structure determination of [C66H48N12O15Cl3Er2]Cl2NO3.5H2O confirms the conclusion from the spectroscopic studies and show that the erbium is at the centre of a tricapped trigonal prism with coordination number nine. In all the complexes the lanthanide ions have substantially similar coordination.

A hydrazonic ligand, o-vanillin acetylhydrazone (H2L) has been prepared and used as chelating agent towards copper(II) ion. The ligand acts like a tridentate ligand in the monodeprotonated (HL-) and dideprotonated (L2-) states. Monoanionic complexes [{Cu(HL)(H2O)}2]•2BF4 and [{Cu(HL)(Hpz)(H2O)}]•NO3 have been isolated. After neutralization the complex [{Cu(L)}2].5/2H2O is obtained. These complexes have been characterized by a range of physicochemical and spectroscopic studies. The X-ray crystal structure of the mononuclear complex [{Cu(HL)(Hpz)(H2O)}]•NO3 was also determined. This crystal is orthorombic with the space group I222, a = 13.417(3), b = 22.662(6), c = 22.518(5) Å, α = β = γ = 90° and Z = 8. The copper ion has a square-pyramidal geometry with the basal donors atoms from the tridentate ligand (ONO) and the pyrazole (N), the apical position being occupied by a coordinated water molecule weakly linked to the copper(II) center. The binuclear complexes exhibit interesting magnetic properties.

The title compound [Dy2(C22H16ClN4O5)3](SCN) 3.(H2O).(CH3OH) has been synthesized and its crystal structure determined by single X-ray diffraction at room temperature. The two nine coordinated Dy(III) are bound to three macromolecules ligand through the phenolic oxygens of the p-chlorophenol moieties, the nitrogen atoms and the carbonyl functions of the hydrazonic moieties. The phenolic oxygen atoms of the 2-hydroxybenzoyl groups are not bonded to the metal ions. In the bases of the coordination polyhedra the six Dy-N bonds are in the range 2.563(13)-2.656(13) Å and the twelve Dy-O bonds are in the range 2.281(10)-2.406(10) Å.

In the title compound, C17H18N4O5·0.47CH3OH, the virtually planar (r.m.s. deviation = 0.128 Å) carbonohydrazide molecule is located on a twofold axis and conformation of its C=N bonds is E. There are short intramolecular O—H...N hydrogen bonds between the hydroxy groups and hydrazide N atoms. In the crystal, bifurcated N—H...(O,O) hydrogen bonds assemble the carbonohydrazide molecules into a three-dimensional network. There are C2 symmetric voids in this network, 47% of which are occupied by disordered methanol molecules.

The title compound, [ZnCl2(C18H14N4O)], crystallizes with two molecules in the asymmetric unit, which differ in the tautomeric (neutral and zwitterionic) forms of the coordinating organic ligand. In both molecules, the ZnII atom adopts a distorted square–pyramidal geometry by two N and one O atoms of the Schiff base ligand and two Cl atoms acting as monodentate chloride anions. The crystal packing is stabilized by N—H...N and N—H...Cl hydrogen bonds, forming a two-dimensional network parallel to the ac plane.

Bull. Chem. Soc. Ethiop. 1995, 9(1), 31-41.

In the title complex, [MnCl2(C13H13N3)]·H2O, the MnII atom is in a distorted square-pyramidal environment, with an Addison τ parameter of 0.037. The coordination geometry is defined by three N-atom donors from the tridentate 2-(pyridin-2-yl)-N-(pyridin-2-ylmethylidene)ethanamine ligand and two terminal Cl atoms. Although the H atoms of the lattice water molecule were not located, O...O distances of 3.103 (7) Å and O...Cl distances of 3.240 (3) and 3.482 (4) Å suggest that hydrogen bonding is responsible for the stabilization of the crystal packing.

In the title compound, C21H17N3O3, the dihydroquinazoline ring adopts a screw-boat conformation and its stereogenic C atom has an S configuration. The dihedral angle between the mean planes of the two hydroxyphenyl rings is 86.61 (12)°. The amino H atom forms an intramolecular hydrogen bond with a phenol O atom, while the hydrazine N atom acts as an acceptor for the H atom of the other phenol group. In the crystal, O—H...N and O—H...O hydrogen bonds and weak C—H...centroid(π-ring) intermolecular interactions are observed, forming chains along [1-10] and [110].

In the title compound, [Ni(C9H9N4O2)2], the NiII ion is situated on a twofold rotation axis and is coordinated by two O and four N atoms from two tridentate {2-amino-2-oxo-N-[(1E)-1-(pyridin-2-yl-κN)ethylidene]acetohydrazidate ligands in a distorted octahedral geometry. In the crystal, N—H...O and N—H...N hydrogen bonds link the molecules into columns in [001]. The porous crystal packing is further stabilized via π–π interactions between the pyridine rings of neighbouring molecules [centroid–centroid distance = 3.746 (3) Å] with voids of 270 Å3.

In the title compound, [Co(C16H19N2O2)2]NO3·H2O, the CoIII ion is located on an inversion center and is six-coordinated by two phenolate O atoms and four amino N atoms from two diamine ligands, forming an octahedral geometry. The water molecule and the nitrate anion are located close to an inversion center, and are thus equally disordered by symmetry. The crystal packing is stabilized by intermolecular O—H...O hydrogen bonds involving the uncoordinated water molecule and the free phenol hydroxyl group with the nitrate anion. N—H...O hydrogen bonds involving the amino groups and the nitrate anions connect the complex molecules along the c axis.

The CoII ion in the title complex, (C4H14N2)2[Co(C2O4)3]·2H2O, is coordinated by three oxalate ions, resulting in a distorted octahedral geometry. Two uncoordinated water molecules are present in asymmetric unit. Intermolecular N—H...O and O—H...O hydrogen bonds between the different entities stabilize the crystal structure.

The asymmetric unit of the title salt, (C4H14N2)[Cu(C2O4)2], consists of one complex anion and two cationic half-molecules, the other halves being generated by inversion symmetry. The CuII atom in the anion is coordinated by two bidentate oxalate ligands in a distorted square-planar geometry. Intermolecular hydrogen bonds, involving the NH groups as donors and O atoms as acceptors, are observed, which lead to the formation of a three-dimensional network structure.

The asymmetric unit of the title complex, [Cu(C11H16N3O)]ClO4, consists of two CuII ions coordinated by Schiff base ligands and two perchlorate anions. The Schiff base molecules are linked to the CuII atoms via three N atoms and one O atom, resulting in a square-planar geometry. Intermolecular hydrogen bonds involving the NH groups as donors and O atoms of the perchlorate anions as acceptors are observed.

In the title complex, [CoK2(C3H2O4)2(H2O)4]n, the Co atom is located on a position with site symmetry 2/m, the K atom and one water molecule are located on a mirror plane, and the malonate and one water molecule are located on a twofold rotation axis. The KI atom is seven-coordinated by four carboxylate O atoms from four malonate ligands and by three water O atoms, forming a distorted polyhedron. The CoII atom is in an almost octahedral environment formed by four carboxylate O atoms from two malonate ligands and two water O atoms. The structure consists of layers parallel to (20overline1) built up from edge-sharing KO7 and CoO6 polyhedra, which are connected by O—H...O hydrogen bonding including water molecules into a three-dimensional network.

The title compound, C7H9N3S2, crystallizes with two unique molecules in the unit cell, both present as thiosemicarbazide tautomers. The molecules differ principally in the dihedral angles between the thiophene ring planes and the planes through the non-H atoms of the hydrazinecarbothioamide units, viz. 9.80 (8)° for one molecule and 19.37 (7)° for the other. The hydrazinecarbothioamide units are reasonably planar, with r.m.s. deviations of 0.001Å for each of the molecules. In the crystal, N—H...S hydrogen bonds link like molecules into R22(8) inversion dimers. A three-dimensional network structure is generated by additional N—H...S hydrogen bonds and weak C—H...S contacts between the unique molecules.

Bull. Chem. Soc. Ethiop. 1993, 7(2) 117-120.

In the title complex, [Cu(C10H11N2O3)(NO3)]·H2O, prepared from the Schiff base N′-(3-methoxy-2-oxidobenzylidene)acetohydrazide, the CuII atom is coordinated by two O atoms and one N atom from the ligand and one O atom from a nitrate group in a distorted square-planar geometry. The CuII atom has a weak interaction with another O atom of the nitrate group. The two O atoms of the tridentate Schiff base ligand are in a trans arrangement. O—H...O and N—H...O hydrogen bonds involving the uncoordinated water molecule are observed.

The title complex, [Zn(NO3)2(C3H4N2)2], contains a ZnII centre with a slightly distorted tetrahedral coordination environment, involving two N atoms from imidazole ligands and two O atoms from nitrate anions. The imino NH groups participate in intermolecular N—H...O hydrogen bonds.

In the title compound, [Cu(NO3)2(C7H8N2O)2], the CuII atom is located on a centre of inversion, and is coordinated by two bidentate benzohydrazide ligands and two monodentate nitrate anions in an axially distorted octahedral geometry within an N2O4 donor set. The crystal structure is stabilized by N—H...O and weak N—H...N hydrogen bonds.

In the title compound, C6H9N2S+·Cl−·CH4N2S, the 4,6-dimethyl-2-thioxo-1,2-dihydropyrimidin-3-ium cation is protonated at one of the pyrimidine N atoms. The cations are bridged by the chloride anions through a pair of N—H...Cl hydrogen bonds. The amino groups of each thiourea adduct interact with the chloride anions through a pair of N—H...Cl hydrogen bonds and the S atom of another thiourea adduct through a pair of N—H...S hydrogen bonds. These interactions result in a layered hydrogen-bonded network propagating parallel to the bc plane. Except for two H atoms, all atoms are on special positions.

In the title complex, [Cu(C9H9N2O2)Cl]·2H2O, prepared from the Schiff base ligand N′-(2-hydroxybenzilidene)acetohydrazide and copper(II) chloride, the CuII atom is coordinated by two O atoms and one N atom from the ligand and by a Cl atom in a distorted square-planar geometry. The two donor O atoms of the tridentate Schiff base ligand are in a trans arrangement. In the crystal structure, there is an extensive intermolecular hydrogen-bonding network; N—H...O, O—H...O and O—H...Cl interactions, involving the uncoordinated water molecules, lead to the formation of a two-dimensional network parallel to the ab plane.

In the title compound, [Ni2Cl2(C20H18N4)(H2O)4]Cl2·2C2H6O, the coordination environment of each Ni2+ ion is distorted octahedral formed by two N atoms from the Schiff base ligand, two O atoms from water molecules and two chloride anions acting as μ2 bridges between the metal ions. The coordinated water molecules are linked to the uncoordinated ethanol molecules and chloride anions by O—H...O and O—H...Cl hydrogen bonds, although the assignment of some of these is tentative. A weak intermolecular O—H...N interaction within the ligand is also observed.

The title cocrystal, [Cu2(C2O4)(NO3)2(C7H9N3)2(H2O)2][Cu2(C2O4)(NO3)2(C7H9N3)2(CH4O)2], is a 1:1 cocrystal of two centrosymmetric CuII complexes with oxalate dianions and Schiff base ligands. In each molecule, the CuII centre is in a distorted octahedral cis-CuN2O4 environment, the donor atoms of the N,N′-bidentate Schiff base ligand and the bridging O,O′-bidentate oxalate group lying in the equatorial plane. In one molecule, a monodentate nitrate anion and a water molecule occupy the axial sites, and in the other, a monodentate nitrate anion and a methanol molecule occupy these sites. In the crystal structure, intermolecular N—H...O, O—H...O and N—H...N hydrogen bonds link the molecules into a network. Weak intramolecular N—H...O interactions are also observed.

The title compound, C22H18N4O2S2, was characterized by 1H and 13C NMR, solid-state IR spectroscopy and X-ray crystallographic techniques. The crystal structure determination reveals that the twisting modes of the two side arms are different [C—N—C—O and C—N—C—N torsion angles = −1.2 (3) and 1.1 (3)°, respectively, in one arm and 24.1 (3) and −5.1 (3)°, respectively, in the other]. The crystal structure involves N—H...O and N—H...S hydrogen bonds.