Novel synthesis of 2‐amino[1,4,5]benzoxadiazepine derivatives via a mild one‐pot reaction

The diazonium salt of 2‐aminophenol 2 was coupled in situ with malononitrile derivatives 3a‐d , 2‐cyanomethylthiazolin‐4‐one 9 , 2‐cyanomethylbenzimidazole 11a , and 2‐cyanomethylbenzothiazole 11b to give 2‐amino[1,4,5]benzoxadiazepine derivatives 6a‐d, 10 and 12a,b via a one‐pot reaction.     

Kinetics and mechanism of the oxidation of a ternary complex involving nitrilotriacetatocobaltate(II) and malonic acid by N-bromosuccinimide

The kinetics of oxidation of [Co^IINM(H₂O)]^3– (N = nitrilotriacetate, M = malonate) by N-bromosuccinimide (NBS) in aqueous solution have been found to obey the equation: d[Co^III]/dt = k ₁ K ₂[NBS][Co^II]_T/{1 + K₂[NBS] + (H⁺/K₁)} where k ₁ is the rate constant for the electron transfer process, K ₁ the equilibrium constant for dissociation of [Co^IINM(H₂O)]^3– to [Co^IINM(OH)]^4– + H⁺, and K ₂ the pre-equilibrium formation constant. Values of k ₁ = 1.07 × 10^–3 s^–1, K ₁ = 4.74 × 10^–8 mol dm^–3 and K ₂ = 472 dm³ mol^–1 have been obtained at 30 °C and I = 0.2 mol dm^–3. The thermodynamic activation parameters have been calculated. The experimental rate law is consistent with a mechanism in which the deprotonated [Co^IINM(OH)]^4– is considered to be the most reactive species compared to its conjugate acid. It is assumed that electron transfer takes place via an inner-sphere mechanism.     

Thermal and spectral studies of 5-(phenylazo)-2-thiohydantoin and 5-(2- hydroxyphenylazo)-2-thiohydantoin complexes of cobalt(II), nickel(II) and copper(II)

Complexes of 5-(phenylazo)-2-thiohydantoin (L¹) and 5-(2-hydroxyphenylazo)-2-thiohydantoin (HL²) with Co(II), Ni(II) and Cu(II) salts have been synthesised and characterized by elemental analysis, conductivity, magnetic susceptibility, UV-Vis, IR, ESR and TG studies. The magnetic and spectral data suggested octahedral geometry for [L¹M(OAc)₂(H₂O)₂]·xH₂O {M=Ni^ll and Cu^ll} and [L¹CuCl₂(H₂O)]·H₂O (dimeric form for the latter), trigonal bipyramidal geometry for [L²Co(OAc)(H₂O)]·2H₂O, square pyramidal geometry for [L²Ni(OAc)(H₂O)]·H₂O and square planar geometry for [L²CuCl]·2H₂O. TG studies confirmed the chemical formulations of these complexes and showed that their thermal degradation takes place in three to five steps, depending on the type of the ligand and the geometry of the complex. The kinetic parameters (n, E^#, A, ΔH^#, ΔS^# and ΔG^#) of the thermal decomposition stages were computed using the Coats-Redfern and other standard equations and are discussed.     

N-2-[3-methylpyridyl]-N′-phenylthiourea transition metal complexes

New complexes of N-2-[3-methylpyridyl]-N-phenylthiourea (HMPyPT) have been prepared from Ni^II, Cu^II, Zn^II, Pd^II, Pt^IV and Au^III chlorides. Three types, containing 1:1, 1:2 and 1:3 metal–ligand ratios, were isolated and characterized. In every case the ligand behaves in a monodentate manner coordinating via the pyridyl nitrogen. Attempts to isolate complexes containing the deprotonated ligand by raising the pH of the reaction mixture from 1.6–5.5 to 8.5 were unsuccessful. The bonding modes and the stereochemistry of the metal complexes have been determined from spectral (i.r., u.v.–vis., ¹H-n.m.r.) and magnetic measurements. The results suggest a square-planar structure for the Pd^II and Au^III complexes, but octahedral geometry for the other metal complexes. Thermal analysis (d.t.a., t.g.a.) measurements on the solid complexes have also been conducted.     

Metal chelates of salicyl-4-aminoantipyrine

The formation constants of salicyl-4-amino-2,3-dimethyl-1-phenyl-3-pyrazoline-5-one (SAAP) complexes with 3d transition metal ions [Cu(II), Ni(II), Co(II), Zn(II) and Mn(II)] have been determined in 60% ethanol-water medium ofμ = 0.1M (NaCl) at 25°C. It is observed that the formation constants for chelates with 3d transition metals follow the order Mn(II) < Co(II) < Ni(II) < Zn(II) < Cu(II). The effects of metal ions, ionic radii, electronegativities and ionization potentials on chelate formation constants are discussed. Complexes of UO₂(II) and Pd(II) have been synthesized and characterised by elemental analysis, electrolytic conductance, IR spectra and magnetic measurements. The ligand forms the complexes PdLCl and UO₂L₂,2H₂O, where L is a uninegatively charged tridentate ligand (ONO donor sets).     

Fused pyridines by a tandem aza‐wittig / heterocyclization strategy: Synthesis of 1,2,4‐triazolo[1,5‐a]pyridines and pyrido[1,2‐b][1,2,4]triazines

The iminophosphorane 1‐amino‐6‐(triphenylphosphoranylideneamino)‐2‐oxo‐4‐phenyl‐1,2‐dihydro‐pyridine‐3,5‐dicarbonitrile 2 prepared from 1,6‐diaminopyridine 1 reacts with heterocumulenes such as carbon disulfide and phenylisocyanate, and with acid chlorides, acid anhydrides and haloketones to give directly the title compounds in an one‐pot aza‐Wittig / heterocyclic‐ring closure process with good yields.     

Gamma-induced radiation polymerization of kaolin composite for sorption of lanthanum,europium and uranium ions from low-grade monazite leachate

Gamma radiation polymerization method was used for the modification of kaolin to produce (poly acrylamide-acrylic acid)-Kaolin (PAM-AA-K). Monazite ore is one of the main resources of uranium and lanthanide elements, therefore, this work focused on sorption of uranium, lanthanum and europium ions from low grade monazite leachate. The removal percent for Eu³⁺, La³⁺ and UO₂ ²⁺ are 94.6, 91.6 and 73.4%, respectively. Monolayer capacity of Eu³⁺, La³⁺ and UO₂ ²⁺ were found to be 54.64, 45.87 and 37.59 mg/g, respectively. The sorption mechanism of lanthanum and europium ions on PAM-AA-K composite mainly takes place as Ln(OH)²⁺, and for uranium as uranyl ion, UO₂ ²⁺.     

Cooperative Formation of Long‐Range Ordering in Water Ad‐layers on Fe3O4(111) Surfaces

The initial stages of water adsorption on magnetite Fe₃O₄(111) surface and the atomic structure of the water/oxide interface remain controversial. Herein, we provide experimental results obtained by infrared reflection–absorption spectroscopy (IRAS) and temperature‐programmed desorption (TPD), corroborated by density functional theory (DFT) calculations showing that water readily dissociates on Fe_tet sites to form two hydroxo species. These act as an anchor for water molecules to form a dimer complex which self‐assembles into an ordered (2×2) structure. Water ad‐layer ordering is rationalized in terms of a cooperative effect induced by a hydrogen‐bonding network.     

Determination of amitriptyline,imipramine and orphenadrine in antidepressant drugs by potentiometry,spectrophotometry and atomic absorption spectrometry

Methods are described for the determination of amitriptyline, imipramine and orphenadrine in some antidepressant drugs. They are based on a prior reaction with ammonium reineckate to form 11 water-insoluble drugreineckate ion-pair complexes. These complexes are (i) used as ion-exchangers in liquid-membrane electrodes responsive to the drug cations, (ii) extracted with nitrobenzene or dissolved in acetonitrile and spectrophotometrically measured at 525 nm and (iii) dissolved in 90% acetone followed by nebulization in an air-acetylene flame for atomic absorption spectrometric measurements of Cr at 358.6 nm. The reaction and monitoring conditions are optimized to permit determination of as little as 10 g/ml of the drugs. Determination of the drugs in some pharmaceutical preparations shows an average recovery of 98.8% of the nominal and a mean standard deviation of 0.8%. The results compare favorably with data obtained by the United States and British Pharmacopoeia methods.     

Studies on bismuth(III) complexes of ligands containing nitrogen/sulfur and extractive procedure for determination of Bi(III)

The coordination behavior of thiosemicarbazide and its thiosemicarbazones towards Bi(III) is the main goal of this investigation. The structure of the isolated complexes has been proved by microanalysis, thermal, spectra (electronic, IR and ms) and voltammetric measurements. The ligands act as neutral or mononegative molecules and the coordination donors were found to be S for HTS; NN for HBTS; NS for HATS and H₂STS and NNS or NSO for H₂DMTS in the complexes. The complexes show thermal decomposition steps ending at 800 °C with a stable fragment. The redox properties of the complexes toward oxidation waves are strongly dependent on = N_thio substituents. At pH 1.5 and excess of iodide, Bi³⁺ forms an orange–yellow [BiI₄]⁻ complex which associated with tricaprylylmethylammonium chloride (TCMAC) forming [TCMA]⁺[BiI₄]⁻ easily extracted into the CHCl₃ layer. The colored organic layer containing the ion pair is determined spectrophotometrically at 490 nm and represents the second goal.