Hadariah Bahron

Synthesis and Characterization of Palladium(II) Schiff Base and their Catalytic Activities for Heck Reaction

The syntheses, physico-chemical and spectroscopic characterization of ovan-type Schiff-base ligands (L1, L2) and their novel mononuclear Pd(II) complexes (PdL1, PdL2) are reported herein. Elemental analysis, FT-IR, 1H NMR as well as magnetic susceptibility measurements characterised the compounds. The catalytic potential of the Pd(II) complexes for Heck coupling reaction were investigated and monitored using GC. It was observed that both Pd(II) complexes displayed properties of good catalysts for the reaction, indicated by 100% conversion of the starting materials to the subtituted alkene product after 6 hours of reaction time at 100°C in inert conditions. The catalytic activity was compared with the reaction without Pd(II) complexes.

Bis{2-[(E)-(4-fluoro-benz-yl)imino-meth-yl]-6-meth-oxy-phenolato}palladium(II).

In the title compound, [Pd(C15H13FNO2)2], the PdII atom is tetracoordinated by two N atoms and two O atoms from the two 2-[(4-fluorobenzyl)iminomethyl]-6-methoxyphenoxy ligands, forming a square-planar geometry. The two N atoms and the two O atoms around the PdII atom are trans to each other. The dihedral angle between the two fluoro-substituted benzene rings is 39.03 (6)°. The molecular structure is stabilized by an intramolecular C—H⋯O hydrogen bond. In the crystal, weak intermolecular C—H⋯π interactions occur.

Bis{2-[1-(benzyl-imino)-eth-yl]phenolato}palladium(II).

In the title compound, [Pd(C15H14NO)2], the Pd atom lies on an inversion center and is coordinated by two ligand molecules through the O and N atoms in a bidentate manner, forming a slightly distorted square-planar geometry. The dihedral angle between the two benzene rings in the ligand is 76.53 (19)°. The molecular packing is stablized by C—H⋯O and C—H⋯π interactions.

Investigation on effects of substituents in N,N′-dibensylidene ethane-1,2-diamine towards corrosion inhibition on steel in 1M HCl

Abstract Schiff base compounds, namely, N,N′-dibensylideneethane-1,2-diamine (baen), N,N′-bis(4-chlorobenzylidene)ethane-1,2-diamine (cbaen), N,N′-bis(4-methyl benzylidene)ethane-1,2-diamine (mbaen) and 4-(((2-4-hydroxybenzylidene amino)ethylimino) methyl)phenol (hbaen) were tested as corrosion inhibitors on mild steel in 1M HCl via polarisation method. These compounds were synthesised from the corresponding substituted benzaldehydes and ethylenediamine. Results indicate that the presence of chloro, methyl and hydroxyl substituents enhance the inhibitive properties of N,N′-dibensylideneethane-1,2-diamine. Cbaen achieved the highest inhibition efficiency of 80·76% at 1 × 10–3 M.

Frequency dependent conductivity studies on PMMA–LiCF3SO3 polymer electrolytes

Abstract Polymer electrolytes composed of poly(methylmethacrylate) as a host polymer and lithium triflate as a salt have been prepared by solution cast technique. Polymer salt complexation has been confirmed by attenuated total reflectance Fourier transform infrared spectral studies. The ac conductivity as a function of temperatures in the frequency range 100 Hz–1 MHz has been carried out. The conductivity–temperature plots found follows the Arrhenius rule. The complex permittivity ϵ* and complex electric modulus M* have been analysed. The dispersion observe at low frequency is due to the space charge effect arising from the electrodes. The modulus spectra reveal that the dispersion deviates from the Debye behaviour. The ionic conductivity relaxation is determined from the maximum of the peaks of the dielectric loss modulus associated with the ac activation energy for ion relaxation E fp=0·337 eV, which agrees well with the dc conduction activation energy E A=0·341 eV. Thus, it is suggested that the dynamic mechanism for the ionic conduction is achieved at the same energy barrier while conducting as well as relaxing.

Bis{2-meth-oxy-6-[(E)-(4-methyl-benz-yl)imino-meth-yl]phenolato}palladium(II) chloro-form monosolvate.

In the title complex, [Pd(C16H16NO2)2]·CHCl3, the PdII cation lies on an inversion center. One Cl atom of the CHCl3 solvent molecule lies on a twofold axis and the C—H group is disordered with equal occupancies about this axis with the other Cl atom in a general position with full occupancy. The PdII cation is four-coordinate and adopts a square-planar geometry via coordination of the imine N and phenolic O atoms of the two bidentate Schiff base anions. The N and O atoms of these ligands are mutually trans. The plane of the benzene ring makes a dihedral angle of 73.52 (10)° with that of the methoxyphenolate ring. In the crystal, molecules of the PdII complex are arranged into sheets parallel to the ac plane, and the chloroform solvent molecules are located in the interstitial areas between the complex molecules. Weak intermolecular C—H⋯O and C—H⋯π interactions stabilize the packing.

Bis{2-[(E)-(4-fluoro-benz-yl)imino-meth-yl]-6-meth-oxy-phenolato-κN,O}nickel(II).

In the title compound, [Ni(C15H13FNO2)2], the NiII atom is tetracoordinated by two N atoms and two O atoms from two 2-[(4-fluorobenzyl)iminomethyl]-6-methoxyphenolate ligands in a square-planar geometry. The two N atoms and two O atoms around the NiII atom are trans to each other, as the NiII atom lies on an inversion centre. In the fluorophenyl group, five C atoms and an F atom are disordered over two sets of positions of equal occupancy. In the crystal, the complex molecules are linked via intermolecular C—H⋯F hydrogen bonds, forming chains along [001].

(E)-2-[1-(3-Amino-4-chloro-phenyl-imino)eth-yl]-4-bromo-phenol.

The title Schiff base compound, C14H12BrClN2O, exists in an E configuration with respect to the central C=N double bond. The amino group adopts a pyramidal configuration. The dihedral angle between the two benzene rings is 76.88 (10)° and an intramolecular O—H⋯N hydrogen bond forms a six-membered ring, generating an S(6) ring motif. In the crystal structure, molecules are linked into chains along [010] via N—H⋯O hydrogen bonds. The presence of π–π interactions [centroid–centroid distance = 3.6244 (12) Å] further stabilizes the crystal structure.

Electrodeposition of Salicylideneaniline and its Corrosion Behavior

Electrodeposition was carried out on mild steel surface in 0.3 M sodium hydroxide solution (70% distilled water: 30% ethanol) containing 0.1 M salicylideneaniline using cyclic voltammetry and chronoamperometry techniques. Both techniques show the formation of the films on the mild steel surface. The corrosion behavior of electrodeposited mild steel was studied using electrochemical impedance spectroscopy (EIS) technique at various immersion times in 0.5 M sodium chloride solution (NaCl). The study indicates that the resistance of mild steel against corrosion increases after being electrodeposited with salicylideneaniline. However the films tend to diminished after 24 hours being immersed in 0.5 M NaCl solution.

6,6′-Dimeth­oxy-2,2′-[(E,E′)-(4-chloro-m-phenyl­ene)bis­(nitrilo­methyl­idyne)]diphenol

The title compound, C22H19ClN2O4, has the appearance of a warped butterfly. One 2-hydroxy-3-methoxybenzylideneamino fragment is planar [with a maximum deviation of 0.056 (3) Å] and forms a dihedral angle of 9.85 (9)° with the central benzene ring. The other fragment is not planar; however, the methoxyphenol group is planar [with the maximum deviation of 0.033 (2) Å] and makes a dihedral angle of 41.7 (3)° with the central benzene ring. The molecule is stabilized by intramolecular O—H⋯N hydrogen bonding. The crystal structure is stabilized by weak intermolecular C—H⋯O hydrogen bonding and C—H⋯π interactions.