Synthesis and X-ray structural studies of Cd(II) and Ni(II) complexes of 5-(4-methoxy phenyl), 5-(2-pyridyl) and 5-(2-methoxy phenyl)-1,3,4-oxadiazole-2-thione

CoII-catalysed synthesis of N-(4-meth-oxy-phen-yl)-5-(pyridin-4-yl)-1,3,4-oxa-diazol-2-amine hemi-hydro-chloride monohydrate

The title compound, C14H12N4O2·0.5HCl·H2O or H(C14H12N4O2)2 +·Cl-·2H2O, arose from the unexpected cyclization of isonicotinoyl-N-phenyl hydrazine carbo-thio-amide catalysed by cobalt(II) acetate. The organic mol-ecule is almost planar and a symmetric N⋯H+⋯N hydrogen bond links two of them together, with the H atom lying on a crystallographic twofold axis. The extended structure features N-H⋯O and O-H⋯Cl hydrogen bonds, which generate [001] chains. Weak C-H⋯Cl inter-actions cross-link the chains. The chloride ion has site symmetry 2. The major contributions to the Hirshfeld surface are from H⋯H (47.1%), Cl⋯H/H⋯Cl (total 10.8%), O⋯H/H⋯O (7.4%) and N⋯H/H⋯N (6.7%) inter-actions.

DFT and TD-DFT study of isomeric 5-(pyridyl)-1,3,4-oxadiazol-2-thiones and 2-methylthio-5-(pyridyl)-1,3,4-oxadiazoles

Internal rotations of pyridine fragment around single bond of isomeric 5-(2', 3' and 4'-pyridyl)-1,3,4-oxadiazol-2-thiones and 2-methylthio-5-(2', 3' and 4'-pyridyl)-1,3,4-oxadiazoles have been performed by DFT (B3LYP) and MP2 methods with RHF/6-31G(d,p) basis set. It was found that the MP2 barrier height lies a few below than DFT barrier heights for all studied compounds. In the molecule of 2-methylthio-5-(2'-pyridyl)-1,3,4-oxadiazole an anomeric effect detected due to a lone pair-lone pair interaction of pyridine and N4 oxadiazole nitrogen atoms. But it not found in the molecule of 5-(2'-pyridyl)-1,3,4-oxadiazol-2-thione. Furthermore, theoretical UV spectra of the compounds were studied using TD-DFT/6-31G(d,p) method. Theoretical transitions located about 10nm in the long-wavelength region relatively to the experimental bands field. Whereas, the theoretical transitions of 2-methylthio-5-(2', 3' and 4'-pyridyl)-1,3,4-oxadiazoles have very good agreement with the position of experimental bands. The longest wavelength band in both of experimental and theoretical spectra of the investigated compounds have been observed for 5-(4'-pyridyl)-1,3,4-oxadiazole-2-thione and 2-methylthio-5-(2'-pyridyl)-1,3,4-oxadiazole. Furthermore, the longest-wavelength experimental band's position are in good agreement with (r²=0.95) the HOMO-LUMO energetic gaps of studied compounds.

N′-[Bis(methylsulfanyl)methylidene]-2-methoxybenzohydrazide

In the title compound, C11H14N2O2S2, the diethyl dithioate groups are inclined slightly to the benzoyl ring, making a dihedral angle of 14.0 (3)°. A short intramolecular N—H...O contact generates anS(6) ring. In the crystal, C—H...O contacts generate aC(8) chain motif along [010].

5-(2-Methylfuran-3-yl)-N-phenyl-1,3,4-oxadiazol-2-amine

In the title compound, C13H11N3O2, the furan ring is disordered over two orientations, with occupancies of 0.902 (2) and 0.098 (2). The dihedral angles between the central oxadiazole ring and the pendant phenyl ring and the furan ring (major disorder component) are 10.12 (11) and 1.76 (15)°, respectively. A short intramolecular C—H...O contact generates anS(6) ring. In the crystal, inversion dimers linked by pairs of N—H...N hydrogen bonds generateR22(8) loops. The dimers are linked by C—H...π and π–π interactions [range of centroid–centroid distances = 3.301 (7)–3.689 (1) Å], generating a three-dimensional network.

Crystal structure of N'-[bis-(ethyl-sulfan-yl)methyl-idene]-2-hy-droxy-4-meth-oxy-benzohydrazide

In the title compound, C13H18N2O3S2, the amide group is in the plane of the -benzoyl ring with a C-N-N-C torsion angle of 177.63 (12)°. The two di-thio-ate groups are in an anti conformation [torsion angles = 173.68 (8) and -9.98 (10)°]. An intra-molecular N-H⋯O hydrogen bond is observed. In the crystal, an O-H⋯O hydrogen bond and a weak C-H⋯O contact involving the same acceptor atom generate an S(6) ring motif and give rise to chains along [010].

Synthesis, spectral characterization, thermal behaviour, antibacterial activity and DFT calculation on N'-[bis(methylsulfanyl) methylene]-2-hydroxybenzohydrazide and N'-(4-methoxy benzoyl)-hydrazinecarbodithioic acid ethyl ester

Two new compounds N'-[bis(methylsulfanyl) methylene]-2-hydroxybenzohydrazide {Hbmshb (1)} and N'-(4-methoxy benzoyl)-hydrazinecarbodithioic acid ethyl ester {H2mbhce (2)} have been synthesized and characterized with the aid of elemental analyses, IR, NMR and single crystal X-ray diffraction data. Compounds 1 and 2 crystallize in orthorhombic and monoclinic systems with space group Pna21 and P21/n, respectively. Inter and intra molecular hydrogen bonding link two molecules and provide linear chain structure. In addition to this, compound 2 is stabilized by CH⋯π and NH⋯π interactions. Molecular geometry from X-ray analysis, geometry optimization, charge distribution, bond analysis, frontier molecular orbital (FMO) analysis and non-linear optical (NLO) effects have been performed using the density functional theory (DFT) with the B3LYP functional. The bioefficacy of compounds has been examined against the growth of bacteria to evaluate their anti-microbial potential. Compounds 1 and 2 are thermally stable and show NLO behaviour better than the urea crystal.