A. M. Hammam

Coordination compounds of heterocyclic azo derivatives. III. Co(II), Ni(II) and Cu(II) complexes of some arylazo-4,5-diphenylimidazole derivatives

The 3d transition metalion [Co(II), Ni(II) and Cu(II)] complexes of some 4,5-diphenylimidazole azo derivatives have been isolated and characterized by chemical analysis, conductance, electronic and IR spectra. These dyes are characterized by a high tendency towards complex formation with the neutral molecules coordinated to the metal ion as bidentate ligands. The molecular formula of the 1:1 and 1:2 complexes are suggested to be [MLX2(H2O)2] and [ML2X2] or [ML2X2]·2H2O respectively, whereX=Cl− or NO3. the different bands observed in the visible spectra of methanolic solutions of the complexes have been assigned to the possible electronic transition type (L →MCT and d-d). It is suggested that the complexes studied have a distorted octahedral geometry.ZusammenfassungEs wurden einige Komplexe von 4,5-Diphenylimidazol-azo-Derivaten mit den 3 d-Übergangsmetallen Co(II), Ni(II) und Cu(II) isoliert und mittels chemischer Analyse, Leitfähigkeitsmessungen und den Elektronen- bzw. IR-Spektren charakterisiert. Diese Farbstoffe zeigen eine sehr starke Tendenz zur Komplexbildung, wobei die neutralen Moleküle als zweizähnige Liganden an das Metallion koordinieren. Die Formeln für die 1:1- und 1:2-Komplexe werden mit [MLX2(H2O)2] und [ML2X2] bzw. [ML2X2]·2H2O vorgeschlagen (X=Cl− oder NO3−). Die verschiedenen Absorptionsbanden in den VIS-Spektren in methanolischer Lösung werden den möglichen e-Übergängen (L →MCT und d-d) zugeordnet. Für die Komplexe werden verzerrte oktaedrische Geometrien vorgeschlagen.

Solvatochromic studies on 2-[(2-hydroxypheny)azo]-4-5-diphenylimidazole

Abstract The visible electronic spectra of the title hydroxyazo compound (abbreviated as HAI) in a number of organic solvents have been studied. It was found that in dilute solutions in basic solvents, HAI exists in an acid-base equilibrium of the type HAI⇌gH+ + AI−. The proportional concentration of the conjugate base (AI−) in the medium is largely dependent on the HAI concentration, the basicity of the organic solvent and the tendency of stabilization of the AI− form through H-bond interaction with the solvent molecules. The low energy visible band of both the HAI and AI− forms are assigned to a transition involving the whole solute molecule associated with intramolecular CT character. The effect of time on the longer wavelength visible band of HAI has been investigated.

Coordinatively Unsaturated Cu(II) Chelates of Arylideneanthranilic Acids and Their Reactivity Towards Lewis Bases

Abstract Cu(II) chelates of five arylideneanthranilic acids and their Lewis base adducts are described. Characterisation of the prepared binary and mixed ligand complexes was accomplished by elemental analysis, electronic and IR spectroscopy as well as conductivity measurements. It was found that five coordinate binary Cu(II) chelates are formed with an intermolecular bridging carboxylate group. The binary chelates were reactive towards Lewis bases (imid, α-pic, quin, bipy, phen) forming mixed ligand complexes which assumed a polymeric distorted octahedral structure.

Oxidation with permanganate in presence of fluoride: Determination of hypophosphite.

A rapid method is described for the determination of hypophosphite by oxidation with permanganate in acid medium in the presence of fluoride to prevent formation of insoluble oxides of manganese. The optimum conditions for visual and potentiometric end-point detection are given. Hypophosphite is oxidized to H(2)PO(-)(3). Under optimum conditions the titrations are fast and exhibit a reasonable potential change at the end-point. The method demonstrates the feasibility of determining amounts of H(2)PO(-)(2) corresponding to 0.08-7 mg of phosphorus.

Comparison of an Indirect Format ELISA on Modified Graphite and Polystyrene Surfaces against Triazines

An indirect format enzyme-linked immuno-sorbent assay (ELISA) on graphite rods (Ø 0.8 mm x 20 mm) and, for comparison, on microtiter plates has been developed against terbuthylazine. For this purpose, a series of 2-aminoalkyl-4-chloro-6-terbuthyl-s-triazine-2,6- diamine ELISA haptens with alkyl spacer lengths of 2, 4, 6, and 8 CH2 groups has been synthesized. The graphite rods or the microtiter plates were covered by a polymerized glutaraldehyde network, and the ELISA haptens have been coupled by imino coupling to the free aldehyde groups of that network. ε-Aminocaproic acid has been used as an agent to block unspecific binding sites. The ELISA was run in a competitive mode, where the immobilized ELISA hapten and the solute terbuthylazine as a target analyte compete for the solute antibody.

Ni(II), Co(II), and Cu(II) Ternary Complexes Containing 2,4,6‐tris(2‐Pyridyl)‐1,3,5‐triazine as Primary Ligand and Dithiooxamide, Thiosemicarbazide as Secondary Ligands

A series of novel dinuclear, mixed‐ligand complexes having the general formula [M2(tpt)(L)4]Cl4 · nH2O where M=Ni(II), Co(II) or Cu(II); tpt = 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine; L = dithiooxamide (dto) or thiosemicarbazide (tsc); n = 2–4, have been synthesized and characterized. The tpt molecule is flexidentate, where it can behave as di‐ or tridentate dinucleating ligand. The coordination mode of tpt to M(II) apparently occurs through the pyridyl and a triazine nitrogen atoms. All the mixed‐ligand complexes are dinuclear with a bridging tpt molecule and having an octahedral structure. The complexes were characterized by chemical analyses, spectral, molar conductance and thermal studies.

Synthesis and Characterization of Co(II), Ni(II) and Cu(II) Complexes of Some 2-Arylhydrazonobenzothiazole Derivatives

Abstract The synthesis of Co(II), Ni(II) and Cu(II) complexes with some arylidenebenzothiazolyl hydrazides has been described. Characterization of the so obtained complexes was accomplished by elemental analyses, electronic and ir spectroscopy as well as conductivity measurements. It is found that the ortho-hydroxy derivative acts as monobasic bi-or tridentate ligand whereas other derivatives act as neutral bidentate ligands. A pseudo-tetrahedral structure is proposed for all the prepared complexes. The stoichiometry and formation constants of the complexes formed in solution have been also determined.

The use of the rotating pt-electrode at zero applied e. m. f. for the microdetermination of monovalent phosphorus in hypophosphorous acid or hypophosphite

SummaryAn amperometric method is described for the microdetermination of monovalent phosphorus using the rotating Pt-electrode vs S. C. E. and zero applied e. m. f. It is based on oxidation of hypophosphorous acid and hypophosphite with KMnO4 to phosphorous acid and phosphite respectively under the following conditions: Acidity 0.05–0.6 and 0.2–1.68N H2SO4 for H3PO2 and NaH2PO2 respectively; NaF: 0.4–1.5%; amounts of P (I): 2.4μg-2.1 mg and 5.4μg-7.24 mg corresponding to hypophosphorous acid and hypophosphite respectively. The method is accurate and can be utilized at concentrations lower than that with the potentiometric method.ZusammenfassungDie amperometrische Mikrobestimmung einwertigen Phosphors mit einer rotierenden Pt-Elektrode gegen eine ges. Kalomelelektrode bei EMK=0 wurde beschrieben. Sie beruht auf der Oxydation der unterphosphorigen Säure bzw. des Hypophosphits mit KMnO4 zu phosphoriger Säure bzw. Phosphit bei einer Acidität von 0,05-0,6 bzw. 0,2-1,68N H2SO4 für H3PO2 bzw. NaH2PO2; 0,4-1,5% NaF; 2,4μg-2,1 mg bzw. 5,4μg-7,24 mg P (I) als H3PO2 bzw. H2PO2−. Das Verfahren ist genau und für geringere Konzentrationen geeignet als die Potentiometrie.