Mostafa M.H. Khalil

SYNTHESIS AND SPECTROSCOPIC STUDY OF Cu(II), Ni(II), AND Co(II) COMPLEXES OF THE LIGAND SALICYLIDENE-2-AMINO THIOPHENOL

The FTIR and Raman spectra of the ligand salicylidene-2-amino thiophenol (SATP) in the wave number range 4000–200 cm−1 are measured and assigned in terms of a Cs symmetry. The results indicate that SATP exhibits a zwitter ion structure of trans configuration in the ground solid state formed via proton transfer from the thiol group (-SH) to the imine group (−CH=N−). SATP complexes with Cu(II), Ni(II) and Co(II) ions are also synthesized and their structure are determined by elemental analysis, conductometric measurements, thermogravimetric analysis (TGA), UV-Visible and FTIR spectra. The complexes are found to have the formula (ML·H2O) for Cu(II) and Ni(II) ions and (NH4)2 [(Co)2L(OH)4] for Co(II) ion.

Group VI Dinuclear Oxo Metal Complexes of Salicylideneimine‐2‐anisole Schiff Base

Interaction of the Schiff base salicylideneimine‐2‐anisole (salanH) with Cr(CO)6 yielded the dicarbonyl derivative Cr2O2(CO)2(salan)2. The dinuclear oxo complex M2O4(salan)2, M˭Mo and W, was isolated from the reaction of M(CO)6 with salanH. Elemental, spectroscopic and magnetic studies of the reported complexes allowed structures to be proposed. The thermal properties of the complexes were investigated by thermogravimetry.

Ruthenium, osmium and rhodium-2,3-bis(2¢-pyridyl)quinoxaline complexes

Ru3(CO)12 reacts with 2,3-bis (2′-pyridyl)quinoxaline (dpq) in benzene in the presence of either 2,2′(dipyridine (dpy) or pyridine (py) to give the mononuclear complexes Ru(CO)3(dpq) (1) and Ru(CO)2(dpq)(py) (2), respectively. On the other hand, reactions of Os3(CO)12 with dpq alone, or in the presence of dipyridine, yield only Os(CO)3(dpq) (3). Spectroscopic studies of the three complexes were consistent with the proposed structures. Reactions of RuCl3 with dpq, under reduced pressure in PhH/EtOH gave bis-[Ru(dpq)2Cl2]Cl (4). Magnetic measurements showed RuIII, d5, to be in a low-spin electronic configuration. Three complexes, Rh2(dpq)2Cl6(5), [Rh(dpq)2Cl2]Cl (6) and Rh(dpq)(py)Cl3(7), were isolated from reactions of RhCl3 with dpq. The type of product was dependent on the reactants and conditions. The complexes exhibit either irreversible or quasi-reversible ligand-based reductions. In addition, the zerovalent complexes (1)–(3) displayed one metal(based oxidation in their cyclic voltammograms, due to the formation of M+ species.

Synthesis, spectroscopic and structural characterization, and antimicrobial studies of metal complexes of a new hexadentate Schiff base ligand. Spectrophotometric determination of Fe(III) in water samples using a recovery test

New Schiff base complexes were prepared using the bioactive antimicrobial bis-Schiff base ligand synthesized by condensation of 2-aminobenzoic acid and 2,2′-(ethylenedioxy)bis(benzaldehyde). The pKA value of the bis-Schiff base was determined through visible spectrophotometric experiments and the stability constants of its complexes were also studied. The structural features of the complexes were determined from their elemental analyses, magnetic susceptibility, molar conductance, and spectral (IR and 1H NMR) studies. Powder XRD indicates that all the complexes are amorphous except the Cr(III) and Cu(II) chelates which are crystalline. The data revealed that the stoichiometries of all prepared complexes are of 1:1 M/L type. The UV–vis absorption spectral data for the complexes suggest an octahedral geometry around the central metal ion. Thermogravimetric data (TG and DTG) were also studied. The kinetic and thermodynamic parameters for thermal decomposition of the complexes were calculated by graphical methods using the Coats–Redfern approach. The antimicrobial activity of the bis-Schiff base and its complexes was tested against a number of bacteria and fungi to assess their inhibiting potential. Most of the complexes exhibit antibacterial activity more than the parent bis-Schiff base. Also Cr(III), Co(II), and Ni(II) complexes have antifungal activity against Candida albicans whereas the parent bis-Schiff base is inactive. A recovery test was also applied for the spectrophotometric determination of Fe(III) in different natural water samples.Graphical abstract

Chromium, molybdenum and ruthenium complexes of chloranilic acid

Chloranilic acid (H2CA) reacts with Cr(CO)6 and CrCl3 to give the tris derivatives Cr(H2CA)3 and Cr(HCA)3. Spectroscopic measurements on the two complexes reveal that the ligand–metal bond is of the semiquinone type. Susceptibility determinations showed effective magnetic moments of 1.82 and 1.07 μB. Examination of Cr(H2CA)3 by cyclic voltammetry revealed two redox reactions due to tautomeric interconversion through electron transfer. Boiling Mo(CO)6 with H2CA in air gave MoO3(HCA) in which the molybdenum atom is in the + 5 oxidation state. The i.r. spectrum of the MoO3(HCA) displayed bands due to terminal M=O bonds. The cluster compound Ru3(CO)12 reacted with H2CA to give Ru3(CO)10(μ-H)(HCA), the i.r. spectrum of which revealed that the ligand is bound to the metal as a catechol moiety. The spectroscopic and magnetic studies of the molybdenum and ruthenium complexes confirmed the proposed structures.

Molybdenum and tungsten complexes of biquinoline. Crystal structure of W(CO)4(2,2′-biquinoline)

M(CO)6 (M = Mo and W) reacts with 2,2′-biquinoline (biq) to yield tetracarbonyl derivatives M(CO)4(biq). Crystals suitable for X-ray structure determination of W(CO)4(biq) were isolated from benzene solution. The u.v.–vis. spectra of the complexes exhibited visible transitions due to metal-to-ligand charge-transfers. Electrochemical investigation of the complexes showed some irreversible, reversible and quasi-reversible redox reactions due to tautomeric interconversions through electron transfer. The thermal properties of the complexes were also investigated using the thermogravimetric technique.

M(co)4[2-(2″-Pyridyl)Benzimidazole] Complexes; m = mo or w

Heating a mixture of M(CO)6, M = Mo or W, and 2-(2′-pyridyl)benzimidazole, PBI, in THF under reduced pressure gave the tetracarbonyl monosubstituted derivative M(CO)4(PBI). Spectroscopic studies showed that these complexes have octahedral structures with two axial and two equatorial carbonyl groups, the PBI ligand occupying two equatorial positions. Electrochemical studies showed reversible and quasi-reversible redox couples due to ligand-based reduction and metal-based oxidation, respectively.

Thermal studies of chromium, molybdenum and ruthenium complexes of chloranilic acid

Abstract Chromium, molybdenum and ruthenium complexes of chloranilic acid (H 2 CA) were investigated by the thermogravimetric (TG) technique. The TG plot of Cr(H 2 CA) 3 showed three decompositions in the temperature range 336–802°K. On the other hand, the TG plot of MoO 3 (HCA) complex displayed successive weight losses in four steps covering the temperature range 350–1278°K. The thermal decomposition of the cluster compound Ru 3 (CO) 10 (μ-H)(HCA) occurred in three steps within the decomposition temperature range 302–764°K. Calculation of the reaction order of decompositions of the three complexes revealed that they follow first-order kinetics. The thermodynamic parameters for the different decomposition steps of the complexes were also determined from their DTG plots.

Biosorption of lanthanum from aqueous solutions using magnetic alginate beads

ABSTRACT Magnetic alginate beads are potential biosorbent for sorption of lanthanum(III) from an aqueous medium. Batch experiments were carried out to study the equilibrium, kinetics, and thermodynamics of lanthanum sorption. The effects of initial solution pH, initial lanthanum concentration, and temperature on lanthanum sorption were investigated. The optimum pH value was defined to be 4. Kinetic and isotherm experiments were carried out at the optimum pH. It was enough to reach the adsorption equilibrium at 4 hours, and the maximum uptake capacity was (1.8 mmol g−1) at 25°C. Uptake kinetics and sorption isotherms were obtained and modeled using conventional and simple equations: best results were respectively obtained with the pseudo-second-order rate equation and the Langmuir equation. The La(III) loaded magnetic alginate beads were regenerated using 0.1 M CaCl2 without activity loss. GRAPHICAL ABSTRACT

Factors Affecting the Efficiency of Excited-States Interactions of Complexes between Some Visible Light-Emitting Lanthanide Ions and Cyclophanes Containing Spirobiindanol Phosphonates

The efficiency of excited-states interactions between lanthanide ions Tb 3 + and Eu 3 + and some new cyclophanes (I, II, and III) has been studied in different media. High luminescence quantum yield values for terbium and europium complexes in DMSO and PMMA were obtained. The photophysical properties of the green and red emissive Tb 3 + and Eu 3 + complexes have been elucidated, respectively.