SHELXT - integrated space-group and crystal-structure determination

Partial conversion of thioamide into nitrile in a copper(II) complex of 2,6-diacetylpyridine bis(thiosemicarbazone), a drug prototype for Alzheimer's disease

This work reports the crystal structure of [(Z)-2-((E)-1-{6-[1-({[amino(sulfanidyl-κS)methylidene]amino}imino-κN)ethyl]pyridin-2-yl-κN}ethylidene)-1-cyanohydrazinido-κN(1)]copper(II), [Cu(C11H11N7S)], the first description of a copper(II) complex of 2,6-diacetylpyridine bis(thiosemicarbazone) showing partial conversion of a thioamide group to a nitrile group. The asymmetric ligand coordinates to the metal centre in an N,N',N'',S-tetradentate manner via the pyridine N atom, an imine N atom, the hydrazinide N atom and the sulfanidyl S atom, displaying a square-planar geometry. Ligand coordination results in two five-membered chelate rings and one six-membered chelate ring, and in crystal packing based on N-H···N hydrogen bonds of the cyanohydrazinide and hydrazinecarbothioamidate arms of the ligand. The correlation between the partial conversion upon metal complexation, H2S release and possible effects on the activity of bis(thiosemicarbazone)s as drug prototypes for Alzheimer's disease is also discussed.

Conformational and structural studies of N-methylacetohydroxamic acid and of its mono- and bis-chelated uranium(VI) complexes

The thermodynamics and kinetics of the cis/trans isomerism of N-methylacetohydroxamic acid (NMAH) and its conjugated base (NMA(-)) have been reinvestigated in aqueous media by (1)H NMR spectroscopy. Hindered rotation around the central C-N bond due to electronic delocalization becomes slow enough on the NMR time scale to observe both rotamers in equilibrium in D2O at room temperature. By properly assigning the methyl group resonances, evidence for the prevalence of the E over the Z form is unambiguously provided [K300=[E]/[Z]=2.86(2) and 9.63(5) for NMAH and NMA(-), respectively], closing thereby a long-lasting dispute about the most stable conformer. To that end, calculations of the chemical shifts by density functional theory (DFT), which accurately reproduced the experimental data, turned out to be a much more reliable method than the direct computation of the relative energy for each conformer. The Z ⇌ E interconversion dynamics was probed at 300 K in D2O by 2D exchange-correlated spectroscopy (EXSY), affording the associated rate constants [kZE=9.0(2) s(-1) and kEZ=3.14(5) s(-1) for NMAH, kZE=0.96(3) s(-1) and kEZ=0.10(2) s(-1) for NMA(-)] and activation barriers at 300 K [ΔG(≠)ZE=68.0 kJ mol(-1) and ΔG(≠)EZ=70.6 kJ mol(-1) for NMAH, ΔG(≠)ZE=73.6 kJ mol(-1) and ΔG(≠)EZ=79.2 kJ mol(-1) for NMA(-)]. For the first time, mono- and bis-chelated uranium(VI) complexes of NMA(-) have been isolated. Crystals of [UO2(NMA)(NO3)(H2O)2] and [UO2(NMA)2(H2O)] have been characterized by X-ray diffractometry, infrared and Raman spectroscopies.

Crystal structure of seleno-l-cystine di-hydro-chloride

Numerous crystal structures are available for the dimeric amino acid cystine. In proteins it is formed by oxidation of the -SH thiol groups of two closely spaced cysteine residues, resulting in the formation of a familiar di-sulfide bridge. The title compound [systematic name: (R,R)-1,1'-dicarb-oxy-2,2'-(diselanedi-yl)diethanaminium dichloride], C6H14N2O4Se2 (2+)·2Cl(-), is the first example of a small mol-ecule structure of the biologically important analogue with a -CH2-Se-Se-CH2- bridging unit. Bond lengths and angles of seleno-l-cystine di-hydro-chloride and its isotypic sulfur analogue l-cystine di-hydro-chloride are compared.

Crystal structure of 1,13,14-tri-aza-dibenz[a,j]anthracene 1,1,2,2-tetra-chloro-ethane monosolvate

The asymmetric unit of the title compound, C19H11N3·C2H2Cl4, consists of one half-mol-ecule of 1,13,14-tri-aza-dibenz[a,j]anthracene (dibenzo[c,h]-1.9,10-anthyridine, dbanth) and one half of 1,1,2,2-tetra-chloro-ethane (TCE), both of which are located on a crystallographic twofold rotation axis. The dihedral angle between the planes of the terminal benzene rings in dbanth is 3.59 (7)° owing to the steric repulsion between the H atoms in the two benzo groups and the H atom in the central pyridine ring of the anthridine skeleton. In the crystal, π-π inter-actions between pyridine rings [centroid-centroid distances = 3.568 (2) and 3.594 (2) Å] link the dbanth mol-ecules to form a one-dimensional columnar structure along the c axis. The dbanth and TCE mol-ecules are connected through weak bifurcated C-H⋯(N,N) hydrogen bonds.

Crystal structure of an unknown solvate of bis-(tetra-n-butyl-ammonium) [N,N'-(4-tri-fluoro-methyl-1,2-phenyl-ene)bis-(oxamato)-κ(4) O,N,N',O']nickelate(II)

In the title compound, [N(C4H9)4]2[Ni(C11H3F3N2O6)] or [N(n-Bu)4]2[Ni(topbo)] [n-Bu = n-butyl and topbo = 4-tri-fluoro-methyl-1,2-phenyl-enebis(oxamate)], the Ni(2+) cation is coordinated by two deprotonated amido N atoms and two carboxyl-ate O atoms, setting up a slightly distorted square-planar coordination environment. The [Ni(topbo](2-) anion lies on a twofold rotation axis. Due to an incompatibility with the point-group symmetry of the complete mol-ecule, orientational disorder of the CF3 group is observed. The tetra-hedral ammonium cations and the anion are linked by weak inter-molecular C-H⋯O and C-H⋯F hydrogen-bonding inter-actions into a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9-18] following unsuccessful attempts to model it as plausible solvent mol-ecule(s). The given chemical formula and other crystal data do not take into account the unknown solvent mol-ecule.

Isolation of 3-amino-4-nitro-benzyl acetate: evidence of an undisclosed impurity in 5-amino-2-nitro-benzoic acid

Yellow crystals of the title compound 3-amino-4-nitro-benzyl acetate, C9H10N2O4, were isolated from the reaction of acetic anhydride with (5-amino-2-nitro-phen-yl)methanol, prepared from reduction of commerically available 5-amino-2-nitro-benzoic acid with borane-THF. The mol-ecule is essentially planar (r.m.s. deviation = 0.028 Å). The mol-ecules are linked by inter-molecular N-H⋯O hydrogen-bonding inter-actions between the carbonyl and amine groups, forming a zigzag chain along the b-axis direction lying in a plane parallel to (-102). The chains are stacked along the c axis by π-π inter-actions [centroid-centroid distances = 3.6240 (3) and 3.5855 (4) Å]. A strong intra-molecular N-H⋯O hydrogen-bonding inter-action is observed between the nitro group and the amine group [2.660 (2) Å].

Crystal structure of trans-bis-(ethane-1,2-diamine-κ(2) N,N')bis-(thio-cyanato-κN)chromium(III) perchlorate from synchrotron data

The structure of the title compound, [Cr(NCS)2(C2H8N2)2]ClO4, has been determined from synchroton data. The asymmetric unit consists of one half of a centrosymmetric Cr(III) complex cation and half of a perchlorate anion with the Cl atom on a twofold rotation axis. The Cr(III) ion is coordinated by the four N atoms of two ethane-1,2-di-amine (en) ligands in the equatorial plane and two N-bound thio-cyanate (NCS(-)) anions in a trans-axial arrangement, displaying a slightly distorted octa-hedral geometry with crystallographic inversion symmetry. The Cr-N(en) bond lengths are in the range 2.053 (16)-2.09 (2) Å, while the Cr-N(thio-cyanate) bond length is 1.983 (2) Å. The five-membered en rings are disordered over two sites, with occupancy ratios of 0.522 (16):0.478 (16). Each ClO4 (-) anion is disordered over two sites with equal occupancy. The crystal structure is stabilized by inter-molecular hydrogen bonds involving the en NH2 groups as donors and perchlorate O and thio-cyanate S atoms as acceptors.

Crystal structure of 4-amino-3-(3-methyl-5-phenyl-1H-pyrazol-1-yl)-1H-1,2,4-triazole-5(4H)-thione

In the title compound, C12H12N6S, the dihedral angles between the central pyrazole ring and the pendant triazole and benzene rings are 68.01 (4) and 59.83 (9)°, respectively. In the crystal, mol-ecules are linked by N-H⋯N and N-H⋯S hydrogen bonds, generating (10-1) sheets.

Crystal structure of 5-(4-methyl-phen-yl)-3-[(E)-2-(4-methyl-phen-yl)ethen-yl]cyclo-hex-2-en-1-one

In the title compound, C22H22O, the dihedral angle between the planes of the benzene rings is 53.55 (7)°. Weak C-H⋯O inter-actions help to direct the packing, forming sheets lying parallel to (020).

Synthesis, crystal structure and spectroscopic properties of trans-dibromidobis(2,2-dimethylpropane-1,3-diamine-κ(2)N,N')chromium(III) perchlorate

The title complex salt, trans-anti-[CrBr2(Me2tn)2]ClO4 (where Me2tn = 2,2-dimethylpropane-1,3-diamine, C5H14N2), was prepared and its structure determined by single-crystal X-ray diffraction at 100 K. The asymmetric unit contains three conformationally similar complex cations and three perchlorate anions. In each complex cation, the Cr(III) centre is coordinated by four N atoms of two chelating Me2tn ligands in the equatorial plane and by two Br atoms in a trans-axial arrangement, to give a distorted octahedral geometry. Interionic contacts are dominated by extensive hydrogen bonding, involving the NH groups of the Me2tn ligand as donors and the anion O atoms or coordinated Br atoms as acceptors, resulting in two-dimensional layers in the bc plane. Ligand field analysis based on the angular overlap model, and IR and electronic spectroscopic properties, are also discussed.

Crystal structure of 1-{3-acetyl-2-(4-chloro-phen-yl)-6-hy-droxy-4-[(2-hy-droxy-prop-yl)amino]-6-methyl-cyclo-hex-3-en-1-yl}ethanone

In the title compound, C20H26ClNO4, the central cyclo-hexene ring adopts an approximate envelope conformation with the C atom binding with the hy-droxy group at the tip of the flap. There is an intramolecular N-H⋯O hydrogen bond generating an S(6) ring motif. In the crystal, classical O-H⋯O hydrogen bonds and weak C-H⋯O and C-H⋯Cl inter-actions link the mol-ecules, forming a three-dimensional supra-molecular architecture. The crystal structure was refined as a four-component twin.

Crystal structure of di-μ-chlorido-bis-[di-chlorido-bis-(methanol-κO)iridium(III)] dihydrate: a surprisingly simple chlorido-iridium(III) dinuclear complex with methanol ligands

The reaction between IrCl3·xH2O in methanol led to the formation of small amounts of the title compound, [Ir2Cl6(CH3OH)4]·2H2O, which consists of two IrCl4O2 octa-hedra sharing an edge via chloride bridges. The mol-ecule lies across an inversion center. Each octa-hedron can be envisioned as being comprised of four chloride ligands in the equatorial plane with methanol ligands in the axial positions. A lattice water mol-ecule is strongly hydrogen-bonded to the coordinating methanol ligands and weak inter-actions with coordinating chloride ligands lead to the formation of a three-dimensional network. This is a surprising structure given that, while many reactions of iridium chloride hydrate are carried out in alcoholic solvents, especially methanol and ethanol, this is the first structure of a chloridoiridium compound with only methanol ligands.

Crystal structure of 1-[2-(2,6-di-chloro-phen-yl)-4,5-diphenyl-1H-imidazol-1-yl]propan-2-ol

The central imidazole ring of the title compound, C24H20Cl2N2O, is twisted with respect to with the planes of the 2,6-di-chloro-benzene and two phenyl rings, making dihedral angles of 74.06 (18), 28.52 (17) and 67.65 (18)°, respectively. The phenyl ring not adjacent to the N-bonded 2-hy-droxy-propyl group shows the greatest twist, presumably to minimize steric inter-actions. In the crystal, mol-ecules are linked by O-H⋯N and C-H⋯O hydrogen-bond contacts into chains along the a-axis direction. The series of parallel chains form a two-dimensional sheet approximately parallel to the bc diagonal. In addition, C-H⋯π inter-actions are observed between the sheets. The atoms of the 2-hy-droxy-propyl group and the N atom of the 1H-imidazole ring to which it is bonded are disordered over two sets of sites, with an occupancy ratio of 0.722 (5):0.278 (5). The structure was refined as an inversion twin.

Crystal structure of poly[di-μ-aqua-{5-[(1Z)-2-(4-chloro-phen-yl)-1-cyano-ethenyl]-1,2,3,4-tetra-zol-1-ido-κN (1)}sodium]

In the title compound, [Na(C10H5ClN5)(H2O)2] n , infinite chains of [Na(H2O)2](+) cations having a diamond-shaped cross-section and running parallel to the b axis are formed. O-H⋯N hydrogen bonds to the anions generate layers parallel to (100) which have the chloro-benzene-cyano-ethenyl substituents protruding from both surfaces. The sodium ion makes a short contact of 2.4801 (13) Å with the N atom of the tetra-zolide ring which is syn to the cyano N atom.

Crystal structure of 4-bromo-2-[(E)-N-(2,2,6,6-tetra-methyl-piperidin-4-yl)carboximido-yl]phenol dihydrate

In the title hydrate, C16H23BrN2O·2H2O, the organic mol-ecule features a strong intra-molecular O-H⋯N hydrogen bond. The piperidine ring, in addition, adopts a chair conformation with the exocyclic C-N bond in an equatorial orientation. The water molecules of crystallization are disordered (each over two sets of sites with half occupancy. In the crystal, they associate into corrugated (100) sheets of (H2O)4 tetra-mers linked by O-H⋯O hydrogen bonds. The organic mol-ecules, in turn, are arranged at both sides of these sheets, linked by water-piperidine O-H⋯N hydrogen bonds.

Crystal structure of bis-[trans-(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ(4) N)bis-(thio-cyanato-κN)chromium(III)] tetra-chlorido-zincate from synchrotron data

The structure of the title compound, [Cr(NCS)2(cyclam)]2[ZnCl4] (cyclam = 1,4,8,11-tetra-aza-cyclo-tetra-decane, C10H24N4), has been determined from synchrotron data. The asymmetric unit contains two independent halves of the Cr(III) complex cations and half of a tetra-chlorido-zincate anion. In each complex cation, the Cr(III) atom is coordinated by the four N atoms of the cyclam ligand in the equatorial plane and by two N-bound NCS(-) anions in a trans axial arrangement, displaying a distorted octa-hedral geometry with crystallographic inversion symmetry. The mean Cr-N(cyclam) and Cr-N(NCS) bond lengths are 2.065 (4) and 1.995 (6) Å, respectively. The macrocyclic cyclam moieties adopt centrosymmetric trans-III configurations with six- and five-membered chelate rings in chair and gauche configurations, respectively. The [ZnCl4](2-) anion, which lies about a twofold rotation axis, has a slightly distorted tetra-hedral geometry. The crystal packing is stabilized by hydrogen-bonding inter-actions between the N-H groups of the cyclam ligands, the S atoms of the NCS(-) groups and the Cl(-) ligands of the anion.

Crystal structure of 4-formyl-pyridine semicarbazone hemihydrate

The mol-ecule of the title compound C7H8N4O·0.5H2O, alternatively called (E)-1-(pyridin-4-yl-methyl-ene)semi-carb-azide hemihydrate, is in the E conformation and is almost planar; the r.m.s. deviation of the positions of the atoms of the pyridine ring from the best-fit plane is 0.0039 Å. The C, N and O atoms of the rest of the mol-ecule sits close on this plane with a largest deviation of 0.115 (4) Å for the O atom of the semicarbazone moiety. There is an intra-molecular N-H⋯N hydrogen bond. In the crystal, mol-ecules are linked into an infinite three-dimensional network by classical N-H⋯Os (s = semicarbazone) and Ow-H⋯N (w = water) hydrogen bonds.

Crystal structure of (2-formyl-phenolato-κ(2) O,O')oxido(2-{[(2-oxidoeth-yl)imino]-meth-yl}phenolato-κ(3) O,N,O')vanadium(V)

In the unsymmetrical title vanadyl complex, [V(C9H9NO2)(C7H5O2)O], one of the ligands (2-formyl-phenol) is disordered over two sets of sites, with an occupancy ratio of 0.55 (2):0.45 (2). The metal atom is hexa-coordinated, with a distorted octa-hedral geometry. The vanadyl O atom (which subtends the shortest V-O bond) occupies one of the apical positions and the remaining axial bond (the longest in the polyhedron) is provided by the (disordered) formyl O atoms. The basal plane is defined by the two phenoxide O atoms, the imino-alcoholic O and the imino N atom. The planes of the two benzene rings are almost perpendicular to each other, subtending an inter-planar angle of 84.1 (2)° between the major parts. The crystal structure features weak C-H⋯O and C-H⋯π inter-actions, forming a lateral arrangement of adjacent molecules.

Crystal structure of 2-methyl-1H-imidazol-3-ium aqua-tri-chlorido-(oxalato-κ(2) O,O')stannate(IV)

The tin(IV) atom in the complex anion of the title salt, (C4H7N2)[Sn(C2O4)Cl3(H2O)], is in a distorted octa-hedral coordination environment defined by three chlorido ligands, an oxygen atom from a water mol-ecule and two oxygen atoms from a chelating oxalate anion. The organic cation is linked through a bifurcated N-H⋯O hydrogen bond to the free oxygen atoms of the oxalate ligand of the complex [Sn(H2O)Cl3(C2O4)](-) anion. Neighbouring stannate(IV) anions are linked through O-H⋯O hydrogen bonds involving the water mol-ecule and the two non-coordinating oxalate oxygen atoms. In combination with additional N-H⋯Cl hydrogen bonds between cations and anions, a three-dimensional network is spanned.

Crystal structure of methyl 2-hy-droxy-5-[(4-oxo-4,5-di-hydro-1,3-thia-zol-2-yl)amino]benzoate

The title compound, C11H10N2O4S, crystallized with two independent mol-ecules (A and B) in the asymmetric unit. They differ primarily in the rotational orientation of the five-membered heterocyclic ring. In mol-ecule A this ring is inclined to the benzene ring by 48.17 (8)°, while in mol-ecule B the same dihedral angle is 23.07 (8)°. In each mol-ecule there is an intra-molecular O-H⋯O hydrogen bond involving the adjacent hydroxyl group and the ester carbonyl O atom. In the crystal, the A mol-ecules are linked via pairs of N-H⋯N hydrogen bonds, forming inversion dimers. These dimers are linked to the B mol-ecules via N-H.·O, C-H⋯O and C-H⋯S hydrogen bonds forming corrugated sheets lying parallel to (102).

Expanding the structural landscape of niclosamide: a highZ′ polymorph, two new solvates and monohydrate HA

Three new crystalline phases are reported for the drug niclosamide [5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide], C13H8Cl2N2O4. A new high-Z′ polymorph (denoted Form II) is described, with four molecules in the asymmetric unit in the space groupP2/n. The structure exhibits pseudosymmetry, including local translations and screw-type operations. The niclosamide molecules are linked by O—H...O hydrogen bonds into chains, and the chains are packed so that the molecules form face-to-face (stacking) and end-to-end interactions within layers perpendicular to the chains. There are two different layer arrangements, giving a structure that is relatively complex. In the acetone and acetonitrile solvates, the incorporated solvent molecules accept hydrogen bonds from the OH groups of niclosamide, and the niclosamide molecules are stacked in a face-to-face manner. In the acetone solvate, C13H8Cl2N2O4·C3H6O, V-shaped arrangements are formed in which the nitrobenzene ends of the niclosamide molecules are brought into face-to-face contact. In the acetonitrile solvate, C13H8Cl2N2O4·CH3CN, stacking occurs by translation along a short axis (ca3.8 Å) and the crystals are frequently observed to be twinned by twofold rotation around that axis. The acetonitrile molecules occupy channels in the structure. A complete structure is provided for niclosamide monohydrate, C13H8Cl2N2O4·H2O, polymorph HA, obtained by Rietveld refinement against laboratory powder X-ray diffraction data. It has been suggested that this compound is related to the methanol solvate of niclosamide [Harriss, Wilson & Radosevljevic Evans (2014).Acta Cryst.C70, 758–763], but it is found that the two are not fully isostructural: they contain isostructural two-dimensional layers, but the layers are arranged differently in the two structures. This suggests that HAmay have the potential for polytypism, and features in the Rietveld difference curve indicate that a polytype fully isostructural with the methanol solvate might be present.

Crystal structure of μ-oxido-1,1'κ(2) O:O-bis{tetra-μ-oxido-1:2κ(2) O:O;1:3κ(2) O:O;2:3κ(4) O:O-tris[1,2,3(η(5))-penta-methyl-cyclo-penta-dien-yl]-trianglo-trititanium(IV)}

The title polynuclear organometallic titanium(IV) oxide, [{Ti3(η(5)-C5Me5)3(μ-O)4}2(μ-O)], exhibits two Ti3O4 cores bridged by an O atom located on a twofold axis. All metal centres present the typical three-legged piano-stool coordination environment, where one site is occupied by a penta-methyl-cyclo-penta-dienyl ligand linked in an η(5)-coordination fashion, while three bridging O atoms fill the other three sites.

Crystal structure of N-[4-amino-5-cyano-6-(methyl-sulfan-yl)pyridin-2-yl]-2-chloro-acetamide

In the title compound, C9H9ClN4OS, the dihedral angle between the acetamide moiety and the pyridine ring is 4.83 (12)°. The O=C-C-Cl torsion angle is 46.4 (3)° and an intra-molecular C-H⋯O inter-action generates an S(6) ring. In the crystal, mol-ecules are linked by N-H⋯O, N-H⋯N and C-H⋯N hydrogen bonds, generating sheets lying parallel to (120).

Crystal structure of tri-chlorido-(4'-ferrocenyl-2,2':6',2''-terpyridine-κ(3) N,N',N'')iridium(III) aceto-nitrile disolvate

In the title compound, [FeIr(C5H5)(C20H14N3)Cl3]·2CH3CN, the central Ir(III) atom is sixfold coordinated by three chloride ligands and three terpyridine N atoms in a slightly distorted octa-hedral fashion. The terpyridine ligand is functionalized at the 4'-position with a ferrocenyl group, the latter being in an eclipsed conformation. In the crystal, mol-ecules are stacked in rows parallel to [001], with the aceto-nitrile solvent mol-ecules situated between the rows. An extensive network of intra- and inter-molecular C-H⋯Cl inter-actions is present, stabilizing the three-dimensional structure.

Crystal structure of cis-aqua-chlorido-bis-(1,10-phenanthroline-κ(2) N,N')chromium(III) tetra-chlorido-zincate monohydrate from synchrotron data

The structure of the title compound, [CrCl(C12H8N2)2(H2O)][ZnCl4]·H2O, has been determined from synchrotron data. The Cr(III) ion is bonded to four N atoms from two 1,10-phenanthroline (phen) ligands, one water mol-ecule and a Cl atom in a cis arrangement, displaying an overall distorted octa-hedral coordination environment. The Cr-N(phen) bond lengths are in the range of 2.0495 (18) to 2.0831 (18) Å, while the Cr-Cl and Cr-(OH2) bond lengths are 2.2734 (7) and 1.9986 (17) Å, respectively. The tetra-hedral [ZnCl4](2-) anion is slightly distorted owing to its involvement in O-H⋯Cl hydrogen bonding with coordinating and non-coordinating water mol-ecules. The two types of water mol-ecules also inter-act through O-H⋯O hydrogen bonds. The observed hydrogen-bonding pattern leads to the formation of a three-dimensional network structure.

Crystal structure of trans-(1,8-dibutyl-1,3,6,8,10,13-hexa-aza-cyclo-tetra-decane-κ(4) N (3),N (6),N (10),N (13))bis-(5-methyltetra-zolato-κN)nickel(II) from synchrotron data

The structure of the title compound, [Ni(C2H3N4)2(C16H38N6)], has been characterized from synchrotron radiation. The asymmetric unit consists of one half of the Ni(II) complex mol-ecule, which is related to the other half-mol-ecule by an inversion center. The Ni(II) ion is coordinated by four secondary N atoms of the macrocyclic ligand in a square-planar fashion in the equatorial plane and by two N atoms of the 5-methyltetra-zolate anions in axial positions, resulting in a tetra-gonally distorted octa-hedral geometry. The average equatorial Ni-N bond length [2.060 (8) Å] is shorter than the axial Ni-N bond length [2.2183 (11) Å]. An intra-molecular N-H⋯N hydrogen bond between the secondary amine N atom of the macrocyclic ligand and the non-coordinating N atom of the 5-methyltetra-zolate ion stabilizes the mol-ecular structure. Moreover, an inter-molecular N-H⋯N hydrogen bond between the macrocyclic ligand and 5-methyltetra-zolate group gives rise to a supra-molecular sheet structure parallel to the bc plane.

Crystal structure of ammonium bis-(pyridine-2,6-di-carboxyl-ato-κ(3) O,N,O')chromate(III) from synchrotron data

The structure of the title compound, (NH4)[Cr(pydc)2] (pydc is pyridine-2,6-di-carboxyl-ate, C7H3NO4), has been determined from synchrotron data. The Cr(III) ion and the N atom of the ammonium cation are located on a crystallographic fourfold rotoinversion axis (-4). The Cr(III) cation is coordinated by four O atoms and the two N atoms of two meridional pydc ligands, displaying a distorted octa-hedral geometry. The Cr-N and Cr-O bond lengths are 1.9727 (15) and 1.9889 (9) Å, respectively. The crystal structure is stabilized by inter-molecular hydrogen bonds involving the N-H groups of the ammonium cation and pyridine C-H groups as donors and the non-coordinating carbonyl O atoms as acceptors.

Crystal structure of bis-[μ-meth-oxy(pyridin-2-yl)methano-lato-κ(3) N,O:O]bis[chlorido-copper(II)]

The racemic title compound, [Cu2(C7H8NO2)2Cl2], is composed of dinuclear mol-ecules in which meth-oxy(pyridin-2-yl)methano-late ligands bridge two symmetry-related Cu(II) ions. Each Cu(II) ion is coordinated in a square-planar geometry by one Cl atom, the N and O atoms of the bidentate ligand and the bridging O atom of the centrosymmetrically related bidentate ligand. The separation between the two Cu(II) atoms is 3.005 (1) Å. In the crystal, non-classical C-H⋯O hydrogen bonds, weak π-π stacking [centroid-centroid distance = 4.073 (1) Å] and weak electrostatic Cu⋯Cl inter-actions [3.023 (1) Å] link the dinuclear mol-ecules into chains running parallel to the b axis. These chains are further connected by weak C-H⋯Cl hydrogen bonds directed approximately along the a axis, forming a three-dimensional supra-molecular network.

Crystal structure of trans-(1,8-dibutyl-1,3,6,8,10,13-hexa-aza-cyclo-tetra-decane-κ(4) N (3),N (6),N (10),N (13))bis-(isonicotinato-κO)copper(II) from synchrotron data

The title compound, [Cu(C6H4NO2)2(C16H38N6)] has been synthesized and characterized by structure analysis based on synchrotron data and by FT-IR spectroscopy. The asymmetric unit consists of half of the Cu(II) complex, the other half being completed by inversion symmetry. The Cu(II) ion has a tetra-gonally distorted octa-hedral coordination sphere with four secondary N atoms of the aza-macrocyclic ligand in the equatorial plane [Cu-Neq = 2.018 (12) Å] and two O atoms of the isonicotinate anions at the axial positions [Cu-Oax = 2.4100 (11) Å]. Intra-molecular N-H⋯O hydrogen bonds between one of the secondary amine N-H groups of the aza-macrocyclic ligand and the non-coordinating O atom of the isonicotinate ions stabilize the mol-ecular structure. Inter-molecular N-H⋯N hydrogen bonds between the other macrocyclic N-H group and the pyridine N atom of an adjacent isonicotinate anion as well as π-π inter-actions [centroid-to-centroid distance 3.711 (2) Å] lead to the formation of rods parallel to [001].

Zn(ii) complex with 2-quinolinecarboxaldehyde selenosemicarbazone: synthesis, structure, interaction studies with DNA/HSA, molecular docking and caspase-8 and -9 independent apoptose induction

A new Zn(ii)-based complex shows a concentration-dependent apoptotic response in highly resistant pancreatic adenocarcinoma cells with extensive activation of caspase-8 and -9.

Addition of phenylacetylene to a magnesium complex of monoiminoacenaphtheneone (dpp-mian)

Reaction of alkoxy-amido magnesium complex 4 with phenylacetylene affords cycloaddition product 6. The protonation of the latter with phenylacetylene results alkoxy-imino derivative 7.

Facile redox state manipulation in Cu(i) frameworks by utilisation of the redox-active tris(4-(pyridin-4-yl)phenyl)amine ligand

Two Cu(i) frameworks were synthesised with the NPy₃ ligand and Cu(ii) salts to yield electroactive Cu(i) frameworks whose spectral properties varied as a function of the redox state.

Synthesis of substituted β-diketiminate gallium hydrides via oxidative addition of H–O bonds

Substituted β-diketiminate gallium hydrides of the general formulaLGa(H)X have been obtained from the oxidative addition reactions of compounds with OH groups intoLGa (L= HC[CMeNAr]₂⁻, Ar = 2,6-iPr₂C₆H₃).

A polymorph of the 6,13-dichloropentacene organic semiconductor: crystal structure, semiconductor measurements and band structure calculations

A new polymorph of the 6,13-dichloropentacene organic semiconductor was discovered, and its properties were compared with those of an earlier reported polymorph.

5-(Fluorodinitromethyl)-2H-tetrazole and its tetrazolates – Preparation and Characterization of New High Energy Compounds

5-(Fluorodinitromethyl)-2H-tetrazole (HFDNTz) has been prepared by the cycloaddition reaction of HN₃ with F(NO₂)₂CCN, which in turn was prepared by aqueous fluorination of sodium dinitrocyanomethanide.

Synthesis and characterization of conjugated/cross-conjugated benzene-bridged boron difluoride formazanate dimers

A study designed to probe the effect of electronic conjugation and cross-conjugation on the optical and electrochemical properties of benzene-bridged boron difluoride formazanate dimers is presented.

Rhodium catalysed conversion of carbenes into ketenes and ketene imines using PNN pincer complexes

PNN pincer-type rhodium complexes catalyze ketene and ketene imine synthesis, using CO or an isocyanide and a carbene precursor.

Preparation and characterization of 3,5-dinitro-1H-1,2,4-triazole

3,5-Dinitro-1H-1,2,4-triazole was isolated as an impact and friction sensitive solid, and fully characterized for the first time. The compound decomposes explosively upon heating to 170 °C. Impurities might lower the decomposition temperature and increase the sensitivity of the material.

Mono- and di-cationic hydrido boron compounds

Stable mono- and di-cationic hydrido boron compounds featuring CH₂BH₂(μ-H)BH₂CH₂ and CH₂BH(μ-H)₂BHCH₂ cores are readily accessible by dehydrogenative hydride abstractions. NBO calculations revealed the occurrence of two B–H–B 3c–2e bonds in the HB(μ-H)₂BH moiety of di-cations (7 and 8), where 43% is located at the H bridges and ∼28% at each boron atom.

Positive and negative allosteric effects of thiacalix[4]arene-based receptors having urea and crown-ether moieties

Allosteric binding behaviors of heteroditopic receptors bearing the 1,3-alternate conformation based thiacalix[4]arene have been evaluated by absorption and ¹H NMR titration experiments.