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1.  N′-(2-Hy­droxy­benzyl­idene)-2-(hy­droxy­imino)­propano­hydrazide 
The mol­ecule of the title compound, C10H11N3O3, adopts an all-trans conformation and is approxomately planar, the largest deviation from the least-squares plane through all non-H atoms being 0.261 (1) Å. An intra­molecular O—H⋯N hydrogen bond occurs. In the crystal, the mol­ecules are packed into layers lying parallel to the ab plane by π-stacking inter­actions between the benzene ring of one molecule and the C—N bond of the oxime group of another molecule; the shortest inter­molecular C⋯C separation within the layer is 3.412 (1) Å. The layers are connected by O—H⋯O and N—H⋯O hydrogen bonds.
doi:10.1107/S1600536811045818
PMCID: PMC3238939  PMID: 22199788
2.  Dichlorido{2-hydroxy­imino-N′-[1-(2-pyrid­yl)ethyl­idene]propanohydrazide-κ3 N,N′,O}zinc(II) hemihydrate 
The title compound, [ZnCl2(C10H12N4O2)]·0.5H2O, was readily prepared by the reaction between ZnCl2 and 2-hydroxy­imino-N′-[1-(2-pyrid­yl)ethyl­idene]propanohydrazide. The Zn atom has a distorted trigonal–bipyramidal geometry with two Cl atoms and one azomethine N atom in the equatorial plane and one pyridine N atom and one amide O atom in the axial positions. In the crystal structure, complex mol­ecules are connected in pairs by N—H⋯Cl hydrogen bonds, formed between the amide NH of one mol­ecule and the Cl atom of a neighboring one. Mol­ecular pairs are connected by hydrogen bonds involving the uncoordinated water mol­ecule, which lies on a twofold axis.
doi:10.1107/S160053680706535X
PMCID: PMC2960173  PMID: 21201313
3.  Diaqua­[N,N′-bis­(2-pyridylmethyl­ene)propane-1,3-diamine]manganese(II) dibromide–aqua­bromido[N,N′-bis­(2-pyridylmethyl­ene)propane-1,3-diamine]manganese(II) bromide–dibromido[N,N′-bis­(2-pyridylmethyl­ene)propane-1,3-diamine]manganese(II) (1/2/1) 
There are three different MnII complexes in the asymmetric unit of the title compound, [Mn(C15H16N4)(H2O)2]Br2·2{[MnBr(C15H16N4)(H2O)]Br}·[MnBr2(C15H16N4)]. In the neutral complex, the Mn2+ ion is six-coordinated in a distorted octa­hedral environment by four N atoms of the tetra­dentate ligand N,N′-bis­(2-pyridylmethyl­ene)propane-1,3-diamine (bppd) and two bromide ligands. In the two cationic complexes, the Mn2+ ions are also six-coordinated in similar environments, but one Mn ion is coordinated by four N atoms of bppd, one Br atom and one O atom of a coordinating water mol­ecule, whereas the other Mn ion is coordinated by four N atoms of bppd and two O atoms of water ligands. The complexes with two coordinated Br atoms or two H2O ligands are disposed about a twofold axis through Mn and C atoms with the special positions (, y, 0) and (0, y, ), respectively. The compound displays inter­molecular O—H⋯Br hydrogen bonding. There are inter­molecular π–π inter­actions between adjacent pyridine rings, with centroid–centroid distances of 3.822 and 3.833 Å, and a C—H⋯O inter­action is also present.
doi:10.1107/S1600536808041731
PMCID: PMC2967905  PMID: 21581533
4.  4-[(E)-(2,4-Difluoro­phen­yl)(hydroxy­imino)meth­yl]piperidinium picrate 
The title compound, C12H15F2N2O+·C6H2N3O7 −, a picrate salt of 4-[(E)-(2,4-difluoro­phen­yl)(hydroxy­imino)meth­yl]piper­idine, crystallizes with two independent mol­ecules in a cation–anion pair in the asymmetric unit. In the cation, a methyl group is tris­ubstituted by hydroxy­imino, piperidin-4-yl and 2,4-difluoro­phenyl groups, the latter of which contains an F atom disordered over two positions in the ring [occupancy ratio 0.631 (4):0.369 (4)]. The mean plane of the hydr­oxy group is in a synclinical conformation nearly orthogonal [N—C—C—C = 72.44 (19)°] to the mean plane of the piperidine ring, which adopts a slightly distorted chair conformation. The dihedral angle between the mean plane of the 2,4-difluoro­phenyl and piperidin-4-yl groups is 60.2 (3)°. In the picrate anion, the mean planes of the two o-NO2 and single p-NO2 groups adopt twist angles of 5.7 (2), 25.3 (7) and 8.3 (6)°, respectively, with the attached planar benzene ring. The dihedral angle between the mean planes of the benzene ring in the picrate anion and those in the hydroxy­imino, piperidin-4-yl and 2,4-difluoro­phenyl groups in the cation are 84.9 (7), 78.9 (4) and 65.1 (1)°, respectively. Extensive hydrogen-bond inter­actions occur between the cation–anion pair, which help to establish the crystal packing in the unit cell. This includes dual three-center hydrogen bonds with the piperidin-4-yl group, the phenolate and o-NO2 O atoms of the picrate anion at different positions in the unit cell, which form separate N—H⋯(O,O) bifurcated inter­molecular hydrogen-bond inter­actions. Also, the hydr­oxy group forms a separate hydrogen bond with a nearby piperidin-4-yl N atom, thus providing two groups of hydrogen bonds, which form an infinite two-dimensional network along (011).
doi:10.1107/S1600536809035363
PMCID: PMC2970333  PMID: 21577832
5.  Crystal structure of 2-hy­droxy­imino-2-(pyridin-2-yl)-N′-[1-(pyridin-2-yl)ethyl­idene]acetohydrazide 
The mol­ecule of the title compound is approximately planar with the planes of the two pyridine rings inclined to one another by 5.51 (7)°. In the crystal, mol­ecules are linked by bifurcated O—H⋯(O,N) hydrogen bonds, forming inversion dimers, which are in turn linked via C—H⋯O and C—H⋯N hydrogen bonds, forming sheets lying parallel to (502).
The mol­ecule of the title compound, C14H13N5O2, is approximately planar (r.m.s deviation for all non-H atoms = 0.093 Å), with the planes of the two pyridine rings inclined to one another by 5.51 (7)°. The oxime group is syn to the amide group, probably due to the formation of an intra­molecular N—H⋯N hydrogen bond that forms an S(6) ring motif. In the crystal, mol­ecules are linked by pairs of bifurcated O—H⋯(O,N) hydrogen bonds, forming inversion dimers. The latter are linked via C—H⋯O and C—H⋯N hydrogen bonds, forming sheets lying parallel to (502). The sheets are linked via π–π stacking inter­actions [inter-centroid distance = 3.7588 (9) Å], involving the pyridine rings of inversion-related mol­ecules, forming a three-dimensional structure.
doi:10.1107/S1600536814025793
PMCID: PMC4257442  PMID: 25552998
crystal structure; hy­droxy­imino; acetohydrazide; pyridyl­ethyl­idene; hydrogen bonding; π–π stacking inter­actions
6.  (E)-N′-(2-Hydroxy­benzyl­idene)-2-(4-isobutyl­phen­yl)propanohydrazide 
The title hydrazide compound, C20H24N2O2, exists in a trans configuration with respect to the acyclic C=N bond and an intra­molecular O—H⋯N hydrogen bond generates an S(6) ring motif. The mean plane through the formohydrazide unit is essentially planar [maximum deviation = 0.025 (2) Å], and forms dihedral angles of 24.45 (16) and 87.14 (16)° with the two benzene rings. In the crystal structure, inter­molecular N—H⋯O and C—H⋯O hydrogen bonds link neighbouring mol­ecules into extended chains along the c axis, which incorporate R 2 2(16) ring motifs. An inter­molecular C—H⋯π inter­action is also observed.
doi:10.1107/S1600536809050971
PMCID: PMC2980184  PMID: 21580121
7.  Ethyl (2E)-2-(hydroxy­imino)propanoate 
The mol­ecule of the title compound, C5H9NO3, is essentially planar [the maximum deviation for a non-H atom from the mean plane is 0.021 (3) Å] due to the π-conjugation of the hydroxy­imino and carbonyl groups, which are trans to each other; ab initio calculations in vacuo at the DFT (B3LYP/6–311G**++) level of theory confirmed that E conformer is indeed the lowest in energy. The packing in crystal structure is influenced by strong inter­molecular O—H⋯N hydrogen-bonding inter­actions between oxime groups and also by π-stacking of the mol­ecules due to the carbonyl and oxime group orbital overlap [inter­planar distance between adjacent mol­ecules = 3.143 (4) Å]. Jointly, these factors afford infinite 6.32 Å thick mol­ecular sheets, where the plane of each mol­ecule is perpendicular to the plane of the sheet. Seen from above, the mol­ecules within the sheet are arranged in a herringbone pattern. Such sheets form a stack due to weak van der Waals inter­actions; the gap between adjacent sheets is 2.07 Å.
doi:10.1107/S1600536810009438
PMCID: PMC2983986  PMID: 21580705
8.  [μ-N,N′-Bis(2-pyridylmethyl­ene)ethane-1,2-diamine]bis­{aqua­[N,N′-bis­(2-pyridyl­methyl­ene)ethane-1,2-diamine]manganese(II)} tetra­kis(perchlorate) 
The cation of the salt, [Mn2(C14H14N4)3(H2O)2](ClO4)4, lies on a center of inversion, the center lying midway along the ethyl­ene chain of the bridging N,N′-bis­(2-pyridylmethyl­ene)ethane-1,2-diamine ligand. The Mn atom is chelated by two atoms N atoms of this bridging ligand, and is also coordinated by four N atoms of another ligand. The Mn atom is seven-coordinated in a penta­gonal-bipyramidal environment. The crystal structure displays inter­molecular π–π inter­actions between adjacent pyridine rings, with a shortest centroid–centroid distance of 3.784 (3) Å. The perchlorate is linked to the dinuclear cation by O—H⋯O hydrogen bonds.
doi:10.1107/S1600536810003764
PMCID: PMC2983616  PMID: 21580209
9.  4-[1-(Hydroxy­imino)ethyl]-N-(4-nitro­benzyl­idene)aniline 
In the title compound, C15H13N3O3, the dihedral angle formed by the two benzene rings is 44.23 (2)°. The crystal structure is stabilized by aromatic π–π stacking inter­actions, with centroid-centroid distances of 3.825 (3) and 3.870 (4) Å between the aniline and the nitro­benzene rings of neighbouring mol­ecules, respectively. In addition, the stacked mol­ecules exhibit inter­molecular C—H⋯N and C—H⋯O inter­actions.
doi:10.1107/S1600536809033753
PMCID: PMC2970305  PMID: 21577917
10.  (E)-Methyl 3-(4-ethyl­phen­yl)-2-{2-[(E)-(hy­droxy­imino)­meth­yl]phen­oxy­meth­yl}acrylate 
In the title compound, C20H21NO4, the two benzene rings are almost perpendicular to each other, making a dihedral angle of 86.1 (7)°. The hy­droxy­ethanimine group is essentially coplanar with the benzene ring, the largest deviation from the mean plane of the hy­droxy­ethanimine [C=N—OH] group being 0.011 (1) Å for the O atom. An intra­molecular C—H⋯O hydrogen bond occurs. The mol­ecules are linked into cyclic centrosymmetric R 2 2(6) dimers via O—H⋯N hydrogen bonds. Inter­molecular C—H⋯O hydrogen bonds link the mol­ecules, forming a C(8) chain along the a axis. The crystal packing is further stabilized by C—H⋯π inter­actions.
doi:10.1107/S1600536811038359
PMCID: PMC3201344  PMID: 22058811
11.  (E)-2-{4-[1-(Hydroxyimino)ethyl]phenyl­iminomethyl}-6-methoxyphenol mono­hydrate 
In the title compound, C16H16N2O3·H2O, the benzene rings are nearly coplanar with each other, forming a dihedral angle of 4.46 (3)°. There is a strong intra­molecular O—H⋯N hydrogen bond which results in a six-membered ring. In the crystal, the mol­ecules are connected into a three-dimensional network via O—H⋯O and O—H⋯N inter­molecular hydrogen bonds, forming a centrosymmetric ring along the b axis with graph-set motif R 4 4(10). In addition, the short distances between the centroids of six-membered rings [3.555 (1) Å], indicate the existence of π–π stacking inter­actions, which may stabilize the crystal structure.
doi:10.1107/S1600536809042032
PMCID: PMC2971266  PMID: 21578358
12.  N-(4-Chloro­phen­yl)-2-(hydroxy­imino)acetamide 
The title compound, C8H7ClN2O2, is an inter­mediate in the synthesis of 5-chloro­isatin, which can be further transformed to 5-chloro-2-indolinone via a Wolff–Kishne reduction. The C2N acetamide plane forms a dihedral angle of 6.3 (3)° with the benzene ring. An intra­molecular C—H⋯O inter­action results in the formation of a six-membered ring. In the crystal, inter­molecular N—H⋯O, N—H⋯N and O—H⋯O hydrogen bonds link the mol­ecules into multimers, forming sheets.
doi:10.1107/S1600536809033315
PMCID: PMC2969878  PMID: 21577646
13.  1-[1-(Hydroxy­imino)eth­yl]-N-(2-methoxy­phen­yl)cyclo­propane­carboxamide 
The title compound, C13H16N2O3, adopts an E configuration with respect to the C=N bond and an intra­molecular N—H⋯N hydrogen bond results in the formation of a six-membered ring. In the crystal, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into a chain propagating along the b axis. Very weak π–π stacking inter­actions [centroid–centroid distance = 4.18 (2) Å] may further consolidate the packing, forming a two-dimensional supra­molecular network.
doi:10.1107/S1600536809022260
PMCID: PMC2969475  PMID: 21582888
14.  4-Chloro-2-((E)-{3-[1-(hydroxy­imino)eth­yl]phen­yl}imino­meth­yl)phenol 
The title compound, C15H13ClN2O2, adopts an E conformation with respect to the azomethine C=N bond. The aniline and phenol rings are almost coplanar, making a dihedral angle of 3.33 (2)°. In the crystal, the mol­ecules lie about inversion centers, forming dimers that are connected by inter­molecular O—H⋯N hydrogen bonds, resulting in six-membered rings with graph-set motif R 2 2(6). In addition, there is a strong inter­molecular O—H⋯N hydrogen-bonding inter­action, resulting in an S(6) ring motif. Weak π–π inter­actions between the benzene rings [centroid–centroid distance = 3.809 (1) Å] further stabilize the crystal structure.
doi:10.1107/S1600536809045942
PMCID: PMC2972112  PMID: 21578758
15.  2-Hydroxy­imino-N′-[1-(2-pyrid­yl)ethyl­idene]propanohydrazide 
The title compound, C10H12N4O2, features an intra­molecular N—H⋯N hydrogen bond formed between the imine NH and oxime N atoms. The oxime group and the amide C=O bond are anti to each other. In the crystal, mol­ecules are connected by O—H⋯O hydrogen bonds into supra­molecular zigzag chains along the c axis.
doi:10.1107/S1600536809033352
PMCID: PMC2969988  PMID: 21577640
16.  (E)-N′-(4-Pyridylmethyl­ene)-4-(8-quinol­yl­oxy)butanohydrazide 0.25-hydrate 
The asymmetric unit of the title compound, C19H18N4O2·0.25H2O, contains two organic mol­ecules and a solvent water mol­ecule with 50% occupancy. The two molecules differ in their conformations: in one mol­ecule it is (+)gauche-trans-trans-(+)gauche-trans, whereas in the other it is (−)gauche-trans-trans-(−)gauche-trans. The dihedral angles between the pyridine ring and the quinoline ring system are 67.4 (3) and 68.0 (2)°. Mol­ecules are linked into a supra­molecular two-dimensional array via N—H⋯N hydrogen bonds, with each partially occupied water mol­ecule connected via an O—H⋯O hydrogen bond. C—H⋯O inter­actions are also present.
doi:10.1107/S160053680900110X
PMCID: PMC2968356  PMID: 21581905
17.  (E)-Methyl 2-({2-eth­oxy-6-[(E)-(hy­droxy­imino)­meth­yl]phen­oxy}meth­yl)-3-phenyl­acrylate 
In the title compound, C20H21NO5, the dihedral angle between the mean planes through the two rings is 47.1 (8)°. The enoate group assumes an extended conformation. The hy­droxy­ethanimine group is essentially coplanar with the benzene ring, the largest deviation from the mean plane being 0.061 (1) Å for the O atom. In the crystal, mol­ecules are linked into cyclic centrosymmetric dimers with an R 2 2(6) motif via pairs of O—H⋯N hydrogen bonds. Inter­molecular C—H⋯O hydrogen bonds form a C(8) chain along the b axis. The crystal packing is further stabilized by C—H⋯π inter­actions.
doi:10.1107/S1600536812014596
PMCID: PMC3344504  PMID: 22590266
18.  N′-[(E)-1-(4-Chloro­phen­yl)ethyl­idene]-2-[4-(2-methyl­prop­yl)phen­yl]propano­hydrazide 
The asymmetric unit of the title compound, C21H25ClN2O, contains four crystallographically independent mol­ecules, which differ mainly in the orientation of the isobutyl groups. The benzene rings are almost orthogonal to each other, forming dihedral angles of 87.40 (6), 88.69 (6), 84.88 (6) and 85.12 (6)° in the four mol­ecules. The crystal structure is stabilized by inter­molecular N—H⋯O and C—H⋯O hydrogen bonds, together with C—H⋯π inter­actions.
doi:10.1107/S1600536808039226
PMCID: PMC2967938  PMID: 21581626
19.  2,2′-(Disulfanediyl)dibenzoic acid–N,N′-bis­(3-pyridyl­meth­yl)ethane­diamide (1/1) 
The asymmetric unit of the title cocrystal, C14H14N4O2·C14H10O4S2, comprises a twisted 2,2′-(disulfanediyl)dibenzoic acid mol­ecule [dihedral angle between the benzene rings = 76.35 (10)°] and a U-shaped N,N′-bis­(3-pyridyl­meth­yl)ethane­diamide mol­ecule with the pyridyl groups lying to the same side of the central diamide moiety [C—C—C—N = 113.8 (2) and −117.6 (2)°]. The latter aggregate into supra­molecular tapes propagating along the a axis via centrosymmetric eight-membered amide {⋯OCNH}2 synthons. Intra­molecular N—H⋯O hydrogen bonds are observed. The 2,2′-(disulfanediyl)dibenzoic acid mol­ecules form carbox­yl–pyridine O—H⋯N hydrogen bonds, bridging a pyridine residue below the plane of the tape and one above the plane with two inter­vening N,N′-bis­(3-pyridyl­meth­yl)ethane­diamide mol­ecules. The supra­molecular chains are consolidated in the crystal packing by C—H⋯O contacts. An inter­molecular C—H⋯S inter­action also occurs.
doi:10.1107/S1600536810036494
PMCID: PMC2983345  PMID: 21587570
20.  Gallic acid pyridine monosolvate 
In the title compound (systenatic name: 3,4,5-trihy­droxy­benzoic acid pyridine monosolvate), C5H5N·C7H6O5, the gallic acid mol­ecule is essentially planar (r.m.s deviation = 0.0766 Å for non-H atoms) and is linked to the pyridine mol­ecule by an O—H⋯N hydrogen bond. An intra­molecular O—H⋯O hydrogen bond occurs in the gallic acid mol­ecule. The gallic acid and pyridine mean planes make a dihedral angle 12.6 (3)°. Inter­molecular O—H⋯O and O—H⋯N hydrogen bonding involving the hy­droxy and carboxyl groups and the pyridine mol­ecule, and π–π inter­actions between inversion-related pyridines [centroid–centroid distance = 3.459 (6) Å] and between pyridine and benzene rings [centroid–centroid distance = 3.548 (6) Å], lead to a three-dimensional network in the crystal.
doi:10.1107/S1600536811043868
PMCID: PMC3247482  PMID: 22220100
21.  (E)-1-Ethyl-4-oxo-N′-(4-pyridylmethyl­ene)-1,4-dihydroquinoline-3-carbo­hydrazide 
In the title compound, C18H16N4O2, the plane defined by the ethyl C atoms and the attached N atom is inclined to the adjacent pyridine ring at an angle of 67.87 (16)°. The dihedral angle between the two heterocyclic rings is 3.33 (16)°. The mol­ecular conformation is stabilized by an intra­molecular N—H⋯O hydrogen bond and the crystal structure by inter­molecular C—H⋯O hydrogen bonds, forming a one-dimensional structure.
doi:10.1107/S160053680903654X
PMCID: PMC2970413  PMID: 21577928
22.  5-(4-Chloro­phen­yl)-3-(2,4-dimethyl­thiazol-5-yl)-1,2,4-triazolo[3,4-a]isoquinoline 
In the title mol­ecule, C21H15ClN4S, the triazoloisoquinoline ring system is approximately planar, with an r.m.s. deviation of 0.054 (2) Å and a maximum deviation of 0.098 (2) Å from the mean plane for the triazole ring C atom that is bonded to the thia­zole ring. The thia­zole and benzene rings are twisted by 66.36 (7) and 56.32 (7)°, respectively, with respect to the mean plane of the triazoloisoquinoline ring system. In the crystal structure, mol­ecules are linked by inter­molecular C—H⋯N inter­actions along the a axis. The mol­ecular conformation is stabilized by a weak intra­molecular π–π inter­action involving the thia­zole and benzene rings, with a centroid–centroid distance of 3.6546 (11) Å. In addition, two other intermolecular π–π stacking inter­actions are observed, between the triazole and benzene rings and between the dihydro­pyridine and benzene rings [centroid–centroid distances = 3.6489 (11) and 3.5967 (10) Å, respectively].
doi:10.1107/S160053681001278X
PMCID: PMC2979146  PMID: 21579114
23.  A triclinic polymorph of (E)-2-(4-iso­butyl­phen­yl)-N′-[1-(4-nitro­phen­yl)ethyl­idene]propano­hydrazide 
The asymmetric unit of the triclinic polymorph of the title compound, C21H25N3O3, consists of two mol­ecules, whereas for the monoclinic polymorph Z′ = 1 [Fun et al. (2009 ▶). Acta Cryst. E65, o445]. The two mol­ecules exhibit an E configuration with respect to the C=N bond. The mol­ecules are linked into dimers by N—H⋯O and C—H⋯O hydrogen bonds forming R 2 2(8) ring motifs. In addition, π–π inter­actions occur between nitro­phenyl groups [minimum centroid–centroid distance 3.940 (2) Å], stacking the molecules along the ac plane.
doi:10.1107/S1600536813019892
PMCID: PMC3793817  PMID: 24109404
24.  2-(4-Isobutyl­phen­yl)-N′-[1-(4-nitro­phen­yl)ethyl­idene]propanohydrazide 
The mol­ecule of the title compound, C21H25N3O3, exists in a trans configuration with respect to the ethyl­idene unit. The dihedral angle between the two substituted benzene rings is 86.99 (7)°. The nitro group is twisted from the attached benzene ring at an angle of 17.02 (7)°. In the crystal structure, mol­ecules are linked by pairs of N—H⋯O hydrogen bonds in a face-to-face manner into centrosymmetric dimers. These dimer units are further linked into chains along the c axis by weak C—H⋯O inter­actions. These chains are stacked along the b axis. The crystal is further stabilized by weak C—H⋯π inter­actions.
doi:10.1107/S1600536809003420
PMCID: PMC2968536  PMID: 21582118
25.  2-Amino­benzoic acid–4-[2-(pyridin-4-yl)eth­yl]pyridine (2/1) 
The asymmetric unit of the title co-crystal, C12H12N2·2C7H7NO2, comprises a centrosymmetric 4-[2-(pyridin-4-yl)eth­yl]pyridine mol­ecule and a 2-amino­benzoic acid mol­ecule in a general position. The acid has a small twist between the carb­oxy­lic acid residue and the ring [dihedral angle = 7.13 (6)°] despite the presence of an intra­molecular N—H⋯O(carbon­yl) hydrogen bond. Three-mol­ecule aggregates are formed via O—H⋯N(pyrid­yl) hydrogen bonds, and these are connected into supra­molecular layers in the bc plane by N—H⋯O(carbon­yl) hydrogen bonds and π–π inter­actions between pyridine and benzene rings [inter-centroid distance = 3.6332 (9) Å]. Layers are connected along the a axis by weak π–π inter­actions between benzene rings [3.9577 (10) Å].
doi:10.1107/S1600536813027128
PMCID: PMC3884291  PMID: 24454067

Results 1-25 (450541)