San-Jun Peng

Synthesis and X-Ray Crystal Structures of Two New Zinc(II) Complexes with Schiff Bases

Two Schiff base compounds, 2-[(3-dimethylaminopropylimino)methyl]phenol (L1) and 2-bromo-4-chloro-6-[(3-methylaminopropylimino)methyl]phenol (L2), react with zinc bromide in methanol solutions, respectively, to give two mononuclear complexes, [ZnBr2L1] (1) and [ZnBr2L2]· 0.5H2O (2). Both complexes were characterized by physico-chemical and spectroscopic methods. X-ray crystallography indicates that the Zn atom in each complex is in a tetrahedral coordination.

(E)-N′-(2-Hydr­oxy-4-methoxy­benzyl­idene)isonicotinohydrazide monohydrate

The title compound, C14H13N3O3·H2O, was prepared by the reaction of 4-methoxysalicylaldehyde and isonicotinohydrazide in ethanol. The Schiff base molecule is not planar and has an E configuration with respect to the methylidene unit. The dihedral angle between the benzene and pyridine rings is 36.8 (2)°. In the molecule there is an intramolecular O—H⋯N hydrogen bond involving the hydroxyl substituent and the N atom of the 2-hydroxy-4-methoxybenzylidene unit. In the crystal, the molecules are linked through intermolecular O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds, forming layers parallel to the bc plane.

Synthesis and Crystal Structure of a Dibridged Dinuclear Cadmium(II) Complex with Schiff Base 2-[(2-Dimethylaminoethylimino)methyl]-6-methoxyphenol

A tetradentate Schiff base compound 2-[(2-dimethylaminoethylimino)methyl]-6-methoxyphenol (HL) reacts with cadmium nitrate and ammonium thiocyanate in a methanol solution to give a dinuclear complex [Cd2L2(μ1,1-NCS)(NCS)(OH2)]. The complex was characterized by physico-chemical and spectroscopic methods. X-ray crystallography indicates that each Cd(II) atom is in a distorted octahedral coordination. The two metal atoms are bridged by one phenolate O and one end-on thiocyanate groups, with the distance of 3.399(3) Å.

3-Hydr-oxy-N'-(2-hydroxy-benzyl-idene)benzohydrazide.

The title compound, C14H12N2O3, was synthesized by the condensation of salicylaldehyde with 3-hydroxybenzohydrazide. The dihedral angle between the two benzene rings is 12.4 (2)°. The 2-hydroxy group forms an intramolecular O—H⋯N hydrogen bond with the imide N atom. Molecules are linked through intermolecular O—H⋯O and N—H⋯O hydrogen bonds into a two-dimensional polymeric structure parallel to the ab plane.

Synthesis, Crystal Structures, and Antimicrobial Activities of Zinc Complexes Derived from Methyl Substituted 2-(Pyridin-2-yliminomethyl)phenols

A new mononuclear zinc(II) complex [ZnL1(MPA)I] (1) (HL1 = 2-[(4-methylpyridin-2-ylimino)methyl]phenol, MPA = 4-methylpyridin-2-ylamine), and a new centrosymmetric dinuclear zinc(II) complex [Zn2L22I2] (2) (HL2 = 2-[(5-methylpyridin-2-ylimino)methyl]phenol), have been synthesized and structurally characterized by elemental analysis and X-ray diffraction. In 1, the Zn atom is four-coordinate in a tetrahedral coordination, while those in 2 are five-coordinate in severely distorted square pyramidal coordinations. The complexes, as well as the two Schiff bases, have been screened and evaluated for their antimicrobial activities.

Synthesis and Crystal Structure of a μ 2-Oxo Bridged Dinuclear Oxovanadium(V) Complex Derived From N′-(2-Hydroxy-4-diethylaminobenzylidene)-3-methylbenzohydrazide

A tridentate hydrazone ligand N′-(2-hydroxy-4-diethylamino benzylidene)-3-methylbenzohydrazide (H2L), reacts with vanadyl sulfate in methanol to give a novel μ 2-oxo bridged dinuclear oxovanadium(V) complex, [V2O2(μ 2-O)L2]. The complex was characterized by physicochemical and spectroscopic methods. The crystal of the complex is triclinic with space group P–1, a = 11.349(2), b = 13.385(3), c = 13.644(2) Å, α = 90.377(2)°, β = 93.772(2)°, γ = 109.239(2)°, V = 1951.8(6) Å3, Z = 2. X-ray crystallography indicates that each V atom is in a distorted square pyramidal coordination. The two V atoms are bridged by one O atom, with a distance of 3.010(1) Å.

Synthesis and Crystal Structure of a Phenolato-bridged Dinuclear Oxovanadium(V) Complex Derived from N’-[1-(2-Hydroxyphenyl)ethylidene]-1H-indole-3-carbohydrazide

A tridentate ligand, N’-[1-(2-hydroxyphenyl)ethylidene]-1H-indole-3-carbohydrazide (H2L), reacts with vanadyl sulfate in methanol to give a centrosymmetric dinuclear complex, [VOL(OCH3)]2. The complex was characterized by physicochemical and spectroscopic methods. The crystal of the complex is monoclinic with space group P21/c, a = 8.345(3), b = 9.469(3), c = 24.087(4) Å, β = 96.290(3)°, V = 1892.1(9) Å3, Z = 4. X-ray crystallography indicates that each VV atom is in a distorted octahedral coordination. The two V atoms are bridged by two phenolate O atoms, with a distance of 3.540(2) Å.

N′-(5-Bromo-2-hydr­oxy-3-methoxy­benzyl­idene)isonicotinohydrazide

The title compound, C14H12BrN3O3, was prepared by reaction of 5-bromo-3-methoxysalicylaldehyde and isonicotinohydrazide in methanol. The molecule is not planar and adopts a trans configuration with respect to the C=N bond. There is an intramolecular O—H⋯N hydrogen bond in the molecule. The dihedral angle between the benzene and pyridine rings is 12.2 (2)°. In the crystal structure, molecules are linked through intermolecular N—H⋯N hydrogen bonds, forming chains running along the c-axis direction.

Bis(2-meth-oxy-6-{[2-(methyl-ammonio)eth-yl]imino-meth-yl}phenolato)thio-cyanato-zinc(II) thio-cyanate hemihydrate.

The title mononuclear zinc(II) complex, [Zn(C11H16N2O2)2(NCS)]NCS·0.5H2O, consists of a complex cation, a thiocyanate anion, and half of a water molecule. The ZnII atom in the cation is five-coordinated by two imine N and two phenolate O atoms from two bidentate Schiff base ligands, and by one N atom of a thiocyanate ligand, forming a distorted trigonal-bipyramidal geometry. The ammonio H atoms are involved in hydrogen bonding with the ligand O atoms and the solvent water molecules (site occupation factor 0.5), which partially determines the conformation of the ligands.

N′-(2-Hydr­oxy-3,5-diiodo­benzyl­idene)-2-methoxy­benzohydrazide

The title compound, C15H12I2N2O3, was synthesized by the condensation of equimolar amounts of 3,5-diiodosalicylaldehyde and 2-methoxybenzohydrazide in a methanol solution. There are two independent molecules, A and B, in the asymmetric unit. The dihedral angle between the two benzene rings is 30.2 (2)° for molecule A and 21.7 (2)° for molecule B. There are intramolecular O—H⋯N and N—H⋯O hydrogen bonds in each molecule. The crystal studied was an inversion twin with a 0.59 (3):0.41 (3) domain ratio.