First row transition metal complexes of (E)-2-(2-(2-hydroxybenzylidene) hydrazinyl)-2-oxo-N-phenylacetamide complexes

Manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and chromium(III) complexes of (E)-2-(2-(2-hydroxybenzylidene)hydrazinyl)-2-oxo-N-phenylacetamide were synthesized and characterized by elemental and thermal (TG and DTA) analyses, IR, UV-vis and (1)H NMR spectra as well as magnetic moment. Mononuclear complexes are obtained with 1:1 molar ratio except [Mn(HOS)(2)(H(2)O)(2)] and [Co(OS)(2)](H(2)O)(2) complexes which are obtained with 1:2 molar ratios. The IR spectra of ligand and metal complexes reveal various modes of chelation. The ligand behaves as a monobasic bidentate one and coordination occurs via the enolic oxygen atom and azomethine nitrogen atom. The ligand behaves also as a monobasic tridentate one and coordination occurs through the carbonyl oxygen atom, azomethine nitrogen atom and the hydroxyl oxygen. Moreover, the ligand behaves as a dibasic tridentate and coordination occurs via the enolic oxygen, azomethine nitrogen and the hydroxyl oxygen atoms. The electronic spectra and magnetic moment measurements reveal that all complexes possess octahedral geometry except the copper complexes possesses a square planar geometry. From the modeling studies, the bond length, bond angle, HOMO, LUMO and dipole moment had been calculated to confirm the geometry of the ligands and their investigated complexes. The thermal studies showed the type of water molecules involved in metal complexes as well as the thermal decomposition of some metal complexes. The protonation constant of the ligand and the stability constant of metal complexes were determined pH-metrically in 50% (v/v) dioxane-water mixture at 298 K and found to be consistent with Irving-Williams order. Moreover, the minimal inhibitory concentration (MIC) of these compounds against Staphylococcus aureus, Escherechia coli and Candida albicans were determined.     

Platinum(II) complexes containing 2-(alkenyl)pyridines

The ligands 2-(allyl)pyridine(APy), and 2-(1-methallyl)pyridine (1-MAPy) react with [Pt₂X₄(PEt₃)₂] (X = Cl or Br), in acetone solution to give complexes of the type [PtX(PEt₃)L] [PtX₃(PEt₃)], (L = APy or 1-MAPy), which contain a bidentate 2-(alkenyl)pyridine, whereas the same reaction in benzene solution gives trans-[PtBr₂(PEt₃)L], (L = APy or 1-MAPy), which contains a monodentate 2-(alkenyl)pyridine; ¹H NMR spectra indicate that both types of product undergo olefin exchange in solution. The same reaction with 2-(3-methallyl)-pyridine [2-(2-butenyl)pyridine] (3-MAPy), 2-(3,3-dimethylallyl)pyridine [2-(3-methyl-2-butenyl)pyridine] (3,3-DMAPy), and 2-(3-butenyl)pyridine (BPy), in either acetone or benzene solution, gives only trans-[PtBr₂(PEt₃)L]. The reaction of trans-[PtBr₂(PEt₃)L] (L = APy or 3-MAPy) with AgClO₄ gives [PtBr(PEt₃)L]ClO₄. Complexes of the type [PtCl₂L], which contain bidentate 2-(alkenyl)pyridines, result on reaction of L = APy, 3-MAPy, 3,3-DMAPy, BPy, MBPy with [Pt₂Cl₄(C₂H₄)₂].     

Synthesis and characterization of new 5-(o-substituted arylazo)-barbituric acid complexes with transition metals

Summary The synthesis of new 5-(o-substituted arylazo)barbituric acid iron(III), cobalt(II), nickel(II) and copper(II) complexes is reported. Electronic spectral data, magnetic moment and e.s.r. measurements were recorded in order to elucidate their geometry and mode of bonding (i.r. evidence). The complexes are non-electrolytes.     

Recent advances of metal phosphides for Li-S chemistry

Li-S batteries have been considered as one of advanced next-generation energy storage systems owing to their remarkable theoretical capacity(1672 m Ah g^-1)and high energy density(2600 Wh kg^-1).However,critical issues,mainly pertaining to lithium polysulfide shuttle and slow sulfur reaction kinetics,have posed a fatal threat to the electrochemical performances of Li-S batteries.The situation is even worse for high sulfur-loaded and flexible cathodes,which are the essential components for practical Li-S batteries.In response,the use of metal compounds as electrocatalysts in Li-S systems have been confirmed as an effective strategy to date.Particularly,recent years have witnessed many progresses in phosphidesoptimized Li-S chemistry.This has been motivated by the superior electron conductivity and high electrocatalytic activity of phosphides.In this tutorial review,we offer a systematic summary of active metal phosphides as promoters for Li-S chemistry,aiming at helping to understanding the working mechanism of phosphide electrocatalysts and guiding the construction of advanced Li-S batteries.     

A new convenient synthesis of 5-aryl-2-(arylamino)-1,3,4-oxadiazole derivatives

Electrical energy offers numerous benefits for conducting a synthesis, including increased reaction rates, yield enhancements and cleaner chemistries. 5-Aryl-2-(arylamino)-1,3,4-oxadiazoles were synthesised directly from acylthiosemicarbazide on the platinum electrode under controlled potential electrolysis in an undivided cell assembly in acetonitrile.     

Recent advances in carbapenem chemistry (review)

Recent synthetic works of carbapenems, focused on their efficiency and applicability to synthesize a variety of substituted carbapenem derivatives for the effective screening research of the new generation carbapenem antibiotics, are reviewed.Part of this review was published in Japanese [Yuki Gosei Kagaku Kyokaishi, 54, 761 (1996); Chem. Abstr., 125, 221386 (1996)].Sumitomo Pharmaceuticals Research Center 1–98, Kasugadenaka 3-chome, Konohana-ku, Osaka 554, Japan. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1475–1493, November, 1998.     

New glyoxime derivatives and their transition metal complexes

Two new vic-dioxime ligands and their complexes with Co⁺², Ni⁺², Cu⁺², Cd⁺², and Zn⁺² ions were synthesized. Primer amines (3,4-methylenedioxaaniline and 4-methylbenzylamine) reacted with antichloroglyoxime to give 3,4-methylenedioxaphenylaminoglyoxime (H₂L¹) and N-(4-methylbenzyl)aminoglyoxime (H₂L²) ligands. Structures of the ligands and their complexes are proposed based on elemental analyses, IR, UV-Vis, and ¹H NMR spectra, magnetic susceptibility measurements, and thermogravimetric analyses (TGA). The article was submitted by the authors in English.     

Thermal behaviour of 6-(2-pyridylazo)-3-acetamidophenol and its metal complexes

The present work aims chiefly to study the thermal behaviour of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with 6-(2-pyridylazo)-3-acetamidophenol (PAAP) in nitrogen atmosphere. The moieties of the prepared complexes contain mainly coordinated water molecules (1-3) together with some water of crystallization. The water molecules of crystallization are removed in a single stage. The decomposition and combustion of the fragments occur in the second and subsequent stages. The fragmentation of the prepared complexes is also studied by mass spectrometry in order to identify the molecular ions obtained. The comparison of thermal analysis (TG) and mass spectra of the compounds is helpful in checking the correct proposed thermal decomposition schemes. This comparative study shows that mass spectra are correlated with the thermal analyses suggestions. The activation thermodynamic parameters of thermal decomposition pathways, such as energy of activation, enthalpy, entropy and free energy change of the complexes are evaluated and the stability of the thermal treated complexes is discussed, which shows that the thermal stabilities of the complexes are enhanced as the ionic radii decrease.     

Formylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal complexes

Summary Formylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal coordination compounds have been synthesized and characterized by elemental analyses, i.r., ¹H-n.m.r., u.v.-vis., t.g.-d.t.a. and molar conductivities. The results show that the ligand coordinates to transition metal ions in the enolic form, accompanied by the release of acetate or nitrate.     

Synthesis and characterization of 5-(arylazo)thiobarbituric acids and their complexes

Summary S-(Arylazo)thiobarbituric acids and their complexes, derived from cobalt(II), nicke(II) and copper(II) were characterized by elemental analyses and spectral measurements. The¹H n.m.r. and i.r. spectra show the ligands to be in the keto-thione form. The strength of the intramolecular hydrogen-bonding is influenced by the electronic requirements of the aryl ring substituents.     

Acetylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal complexes

Summary Acetylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal coordination compounds were prepared. The composition and properties of the ligand and the nature of metal to ligand bonding in its coordination compounds were characterized by elemental analyses, i.r. spectra, n.m.r. spectra, u.v.-vis. spectra, thermal analyses and molar conductivities.     

Recent advances in the chemistry of phenazine oxides (review)

Data on the electronic structures and spectral characteristics of phenazine 5-oxides and 5, 10-dioxides are correlated. Methods for the synthesis of N-oxides of the phenazine series and their reactions (reduction, electrophilic and nucleophilic substitution, and photochemical transformations) are examined. Data on the natural compounds of this series are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1587–1599, December, 1977.     

Chemistry of 2-(arylazo)phenolate complexes of ruthenium. Synthesis,structure and reactivities

A group of six ruthenium(III) complexes of type [Ru(acac)(L)₂]where acac=acetylacetonate anion and L=2-(arylazo)-4-methylphenolate anion or 1-(phenylazo)-2-naphtholate anion have been synthesized and characterized Structural characterization of a representative complex where L=1-(phenylazo)-2-naphtholate anionshows that the azophenolate ligands are coordinated as NO-donor ligands forming six-membered chelate rings The complexes are paramagnetic (low-spin d⁵S=1/2) and show rhombic ESR spectra in 1:1 dichloromethane–toluene solution at 77 K In carbon tetrachloride solution these complexes show intense LMCT transitions in the visible region together with weak ligand-field transitions in the near-IR region All the complexes display two cyclic voltammetric responses a ruthenium(III)–ruthenium(IV) oxidation in the range of 083 to 103 V vs SCE and a ruthenium(III)–ruthenium(II) reduction in the range of −024 to −052 V vs SCE Formal potentials of both the couples correlate linearly with the Hammett constant of the para substituent in the arylazo fragment of the 2-(arylazo)-4-methylphenolate ligand The ruthenimn(IV) and ruthenium(II) congeners of the [Ru^III(acac)(L)₂] complexes have been generated by chemical or electrochemical methods and they have been characterized by electronic spectroscopy and cyclic voltammetry.     

Iridium(III) complexes formed by O-H and/Or C-H activation of 2-(arylazo)phenols

Reaction of 2-(arylazo)phenols with [Ir(PPh(3))(3)Cl] in refluxing ethanol in the presence of a base (NEt(3)) affords complexes of three different types, viz. [Ir(PPh(3))(2)(NO-R)(H)Cl] (R = OCH(3), CH(3), H, Cl and NO(2)), [Ir(PPh(3))(2)(NO-R)(H)(2)] and [Ir(PPh(3))(2)(CNO-R)(H)]. Structures of the [Ir(PPh(3))(2)(NO-Cl)(H)Cl], [Ir(PPh(3))(2)(NO-Cl)(H)(2)] and [Ir(PPh(3))(2)(CNO-Cl)(H)] complexes have been determined by X-ray crystallography. In the [Ir(PPh(3))(2)(NO-R)(H)Cl] and [Ir(PPh(3))(2)(NO-R)(H)(2)] complexes, the 2-(arylazo)phenolate ligands are coordinated to the metal center as monoanionic bidentate N,O-donors, whereas in the [Ir(PPh(3))(2)(CNO-R)(H)] complexes, they are coordinated to iridium as dianionic tridentate C,N,O-donors. In all three products formed in ethanol, the two PPh(3) ligands are trans. Reaction of 2-(arylazo)phenols with [Ir(PPh(3))(3)Cl] in refluxing toluene in the presence of NEt(3) affords complexes of two types, viz. [Ir(PPh(3))(2)(CNO-R)(H)] and [Ir(PPh(3))(2)(CNO-R)Cl]. Structure of the [Ir(PPh(3))(2)(CNO-Cl)Cl] complex has been determined by X-ray crystallography, and the 2-(arylazo)phenolate ligand is coordinated to the metal center as a dianionic tridentate C,N,O-donor and the two PPh(3) ligands are cis. All of the iridium(III) complexes show intense MLCT transitions in the visible region. Cyclic voltammetry shows an Ir(III)-Ir(IV) oxidation on the positive side of SCE and an Ir(III)-Ir(II) reduction on the negative side for all of the products.     

Synthesis of 5-(4-aminophenyl)-2-(arylamino)-1,3,4-thiadiazoles and their schiff base derivatives as antimycobacterial agents

The condensation reaction of 5-(4-aminophenyl)-N-aryl-1,3,4-thiadiazol-2-ylamines with salicyl-aldehyde, 3-hydroxybenzaldehyde, 4-hydroxybenzaldehyde, 5-bromosalicylaldehyde, 5-chlorosalicyl-aldehyde, 4-methoxybenzaldehyde, 3-nitrobenzaldehyde, and 4-nitrobenzaldehyde results in series of new Schiff bases. The synthesized compounds were tested for their antimicrobial efficiency against Mycobacterium smegmatis PTCC 1307 in vitro. All compounds showed significant antiproliferative activity against M. smegmatis.     

2-羟基-1-萘醛缩乙二胺Schiff碱及其过渡金属配合物的合成和表征

Schiff 碱配体包含着酚氧桥氧原子和亚胺氮原子这类强电子给体,他们与过渡金属原子有较强的配位能力,在催化、抗癌、抗菌、抗病毒等方面都有广泛的应用[1-4],受到人们的高度关注.