Zur Kinetik der Aquation von Dimethylsulfoxid-pentaamminkobalt(III)-triperchlorat-dihydrat [Co(NH3)5DMSO](ClO4)3 · 2H2O

Kinetics of the Aquation [Co(NH₃)₅DMSO](ClO₄)₃ · 2 H₂O The aquation rate constants of (dimethylsulfoxide)pentaamminecobalt(III)perchlorate in aqueous perchloric acid media has been determined spectrophotometrically under various conditions of acidity and complex concentrations at 25–50°C. The reaction proceeds by an first-order rate law presumably with D-mechanism, and is independently of the acidity. The values for the activation enthalpy and entropy has been calculated: ΔH≠ = 24,7 kcal mol^?1; ΔS≠ = 4,5 cal K^?1 mol^?1.     

Coulometric determination of amine-substituted derivatives of 1,2,4-triazole in mono- and mixed-ligand complexes of metals

A procedure is developed for the coulometric determination of amine-substituted derivatives of 1,2,4-triazole. Stoichiometric coefficients of 1,2,4-triazoles and transition metal complexes with these ligands in bromination reactions are determined. The data obtained are used to determine the concentration of 4-amino-1,2,4-triazole in iron(II) mixed-ligand complexes of the composition Fe(TR)_3x(4-ATR)_{3 ? 3x}(ClO₄)₂, where TR is 1,2,4-triazole and 4-ATR is 4-amino-1,2,4-triazole that are characterized by the thermoinduced ¹A₁ ai ⁵T₂ spin transition and thermochromism (color change from pink to white and vice versa).     

Synthesis,spectroscopic studies,and crystal structure of 2,6-diacetylpyridinediphenylhydrazone perchlorate and its complexing ability toward the lanthanides

2,6-diacetylpyridinediphenylhydrazone perchlorate was prepared and characterized by spectroscopic (IR, ESI–MS, UV–Vis, ¹H NMR) and analytical data and its crystal structure was determined by single X-ray analysis. The lanthanum(III), praseodymium(III), and neodymium(III) perchlorate complexes of 2,6-diacetylpyridinediphenylhydrazone were prepared in a direct reaction of the ligand with appropriate metal perchlorates. The spectroscopic and analytical data indicate 1:2 metal to ligand stoichiometry. In all the complexes the hydrazones act as monodeprotonated terdentate NNN donor chelators. The same lanthanum(III) complex was also obtained in a one-step condensation reaction between 2,6-diacetylpyridine and phenylhydrazine in the presence of lanthanum(III) perchlorate.     

Thermal behaviour of chromium (III) perchlorate hexahydrate

Thermal behaviour of intimate mixtures of chromium(III) oxide and lithium¹, potassium², rubidium³, cesium³ and thallium(I)⁴ perchlorates revealed that chromium(III) oxide not only catalyses the decomposition by lowering the decomposition temperatures of the pure metal perchlorates but also chemically interacts resulting in the formation of metal dichromate. The oxidation of chromium(III) into the hexavalent state is attributed to the abstraction of oxygen from the perchlorate moiety during the decomposition. In this context, it was thought interesting to study the thermal behaviour of chromium(III) perchlorate and to identify the decomposition products in order to find out whether chromium(III) is oxidized into chromium(VI) by the perchlorate group. Except for a report⁵ on the preparation of chromium(III) perchlorate with different molecules of water of hydration no work seems to have been carried out on the thermal decomposition of this compound. In the present study, the decomposition characteristics are followed by TG and DTA techniques and the decomposition products have been examined by chemical analysis, X-ray powder diffraction patterns and infrared spectral measurements.     

Die Acylierung von 5-Amino-1 H-1, 2, 4-triazolen. Eine 13C-NMR.-Studie

The Acylation of 5-Amino-1 H-1,2,4-triazoles. A ¹³C-NMR. Study The acylation of 3-substituted-5-amino-1 H-1,2,4-triazoles (1) with methyl chloroformate or dimethylcarbamoyl chloride yielded mainly 1-acyl-5-amino-1,2,4-triazoles ( 2 and 3 ). Acylation of 3-methyl-, 3-methoxy- and 3-methylthio-5-amino-1 H-1,2,4-triazole ( 1b , 1c and 1d ) with methyl chloroformate gave up to 10% of the 1-acyl-3-amino-1,2,4-triazoles. For the unsubstituted 5-amino-1,2,4-triazole (1a) , a (1:1)-mixture of the 3- and 5-isomers 2a and 4 was obtained in dioxane in the presence of triethylamine. No 4-acylated product was detected in contrast to earlier reports. The structures of the reaction products were determined with the aid of proton coupled ¹³C-NMR. spectra using the corresponding N-methyl-1,2,4-triazoles as reference compounds.     

Alkylation of C- and N-aminotriazoles with α-iodoketones

C- and N-Amino-1,2,4-triazoles react with 1-iodopropan-2-one in the absence of bases and phasetransfer catalysts (40°C, 9-12 h) to furnish 3-amino-1,4-bis(2-oxo-propyl)-4H-1,2,4-triazolium triiodide and 4-amino-1-(2-oxopropyl)-4H-1,2,4-triazolium iodide. The alkylation of 1,2,4-triazol-4-amine with 1-iodopropan-2-one and 1,3-diiodopropan-2-one in the presence of elemental iodine led to the formation of 4-amino-1-(2-oxopropyl)-4H-1,2,4-triazolium triiodide and 2-oxopropane-1,3-diylbis(4-amino-4H-1,2,4-triazolium) bis(triiodide). Triiodides are oily fluids possessing electric conductivity of 1.1 × 10^?3 Ω m^?1 opening the route to new types of electroconducting ionic liquids.     

Synthesis of heterocycles. Part VI. Synthesis and antimicrobial activity of some 4-amino-5-aryl-1,2,4-triazole-3-thiones and their derivatives

4-Amino-5-aryi-1,2,4-triazole-3-thiones I react with acid chlorides to yield 4-acylamino-5-aryl-1,2,4-triazole-3-thiones II. Compounds I also react with methylene iodide, chloroacetonitrile and methyl bromoacetate to give bis-(4-amino-5-aryl-1,2,4-triazol-3-ylthio)methanes III, 4-amino-5-aryl-3-cyanomethylthio-1,2,4-triazoles IV and 4-amino-5-aryl-3-carbomethoxymethylthio-1,2,4-triazoles V, respectively. Compounds V react with hydrazine hydrate to give the corresponding acid hydrazides VI which in turn condenses with acid chlorides and aldehydes to afford respectively 1-[(4-amino-5-aryl-1,2,4-triazol-3-ylthio)acetyl]-2-aroylhydrazines VII and aryl methylene (4-amino-5-aryl-1,2,4-triazol-3-ylthio)acethydrazones VIII. The antimicrobial activities of the above compounds were screened against different strains of bacteria and fungi.     

Pt(II) complexes of 4-amino-4H-1,2,4-triazole

The coordination ability of 4-amino-4H-1,2,4-triazole with Pt(II), both in solution and solid states, is elucidated by conventional and linear-polarized IR spectroscopy of oriented colloid suspensions in nematic host, ¹H- and ¹³C-NMR, UV-Vis spectroscopy, mass spectrometry (ESI and FAB), TGV, and DSC methods. The interpretation of the spectroscopic characteristics of corresponding metal complexes is obtained by comparison with free 4-amino-4H-1,2,4-triazole. In addition, quantum chemical calculations of the last compound are performed to obtain data for electronic structures and optical properties of the ligand, thus supporting the experimental elucidation. The evaluation of the cell viability on a panel of human tumor cell lines is made. The new Pt(II) complexes exerted cytotoxic effects in a concentration-dependent manner.     

Synthesis of certain 1,2,4-triazole nucleoside derivatives

The syntheses of 3-amino-4-methyl-1-(β-D-ribofuranosyl)-1,2,4-triazolin-5-one ( 8a ) and its 2′-deoxy analog 8b as well as 5-amino-2-methyl-1-(β-D-ribofuranosyl)-1,2,4-triazolin-3-one ( 12 ) have been accomplished. Compounds 8a and 8b were synthesized via glycosylation of 3-bromo-5-nitro-1,2,4-triazole which was followed by replacement in three steps of the 3-bromo function to yield 3-nitro-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-1,2,4-triazolin-5-one ( 4a ) and its 2′-deoxy analog 4b . Compounds 4a and 4b were methylated at N², hydrogenated and deblocked to give 3-amino-4-methyl-1-(β-D-ribofuranosyl)-1,2,4-triazolin-5-one ( 8a ) and the 2′-deoxy analog 8b . Compound 12 was synthesized by glycosylation of 3-amino-1-methyl-1,2,4-triazolin-5(2H)-one ( 10 ). The structures of 8b and 12 were confirmed by single crystal X-ray diffraction analysis.     

Synthesis,characterization and biological activity of Hg(II), Fe(III) complexes with 1,3,4-oxadiazole, 1,2,4-triazole derivatives from L-methionine

Four novel heterocyclic1,3,4-oxadiazole, 1,2,4-triazole derivatives, namely: 5-[1-amino-3-(methylsulfanyl)propyl]-1,3,4-oxadiazole-2(3H)-thione (4), 4-amino-5-[1-amino-3-(methylsulfanyl)propyl]-4H-1,2,4-triazole-3-thiol (5), 1-amino-3-[1-amino-3-(methylsulfanyl)propyl]-1H-1,2,4-triazole-5-thiol (7), and 5-[1-amino-3-(methylsulfanyl)propyl]-1H-1,2,4-triazole-3-thiol (9) have been synthesized from l-methionine and characterized by different spectroscopic techniques (FT-IR, UV–Vis, ¹H NMR, ¹³C NMR and MS). Complex formation with Hg⁺⁺ and Fe⁺⁺⁺ ions were formed from the four heterocyclic 4, 5, 7 and 9. The antimicrobial activities for synthetic intermediates and final four products were assisted using paper disk diffusion method against Gram-negative bacteria: Escherichia coli, Pseudomonas aeroginosae and Gram-positive bacteria: Staphylococus aureus 25923, Staphylococus aureus 43300 and showed variant activity against some of the microorganisms tested.     

Arylierungen von cyclischen Guanidin-Analogen mit α-halogenierten Anthrachinonen: neue Anthrapyrimidine

Arylation Reaction of Cyclic Guanidine-Analogs with α-Halo- anthraquinones: New Anthrapyrimidines 2-Amino-benzimidazole gives on Ullmann-reaction with α-halo-athraquinones such as 1-amino-4-bromoanthraquinone-2-sulfonic acid (la) the new benzimidazo-anthrapyrimidine 2a , whereas 3-amino- triazole gives under the same conditions two products: the 1,2,4-triazoloanthrapyrimidine 7 and l-amino-4-(3-amino-1,2,4- triazolyl)anthraquinone-2-sulfonic acid ( 8 ). The new structures were elucidated by ¹H- and ¹³C-NMR. and X-ray analysis.     

On the mechanism of cobalt(III) aminates pyrolysis

Pyrolysis of the complex (ato-N²)pentaammincobalt(III) perchlorate and the ligand 5-nitrotetrazole, and also of the initial complex aquapentaammincobalt(III) perchlorate was studied by the mass spectroscopy method. The leading oxidizer of ligands in the complexes is changed for the outer-sphere perchlorate ion at the pyrolysis temperature of ~250°C.     

Photochemical reactions of group VIB metal carbonyls with heterocyclic Schiff bases derived from 4-amino -3-hydrazino-5-mercapto-1,2,4-triazole

The new complexes, M(CO)₅(Schiff base) [M?=?Cr; 1, Mo; 2, W; 3, Schiff base?=?4-salicylidenamino-3-hydrazino-5-mercapto-1,2,4-triazole, SAHMT, a; 4-(2-hydroxynaphthylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole, 2HNAHMT, b; 4-(3-hydroxybenzylidenamino)-3-hydrazino-5-mercapto-1,2,4- triazole, 3HBAHMT, c; 4-(4-hydroxybenzylidenamino)-3-hydrazino-5-mercapto-1,2,4- triazole, 4HBAHMT, d; 4-(5-bromosalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole, 5BrSAHMT, e; were synthesized by photochemical reaction of metal carbonyls M(CO)₆ (M?=?Cr, Mo, W) with new heterocyclic Schiff bases derived from 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole, a–e. The ligands and complexes have been characterized by elemental analysis, EI-mass spectrometry, FT-IR, ¹H and ¹³C-{¹H}-NMR spectroscopy. The spectroscopic studies show that Schiff bases, a–e, are monodentate and coordinate via azomethine N donor to the central metal atom in M(CO)₅(Schiff base) (M?=?Cr, Mo, W).     

Acid-mediated cycloalkylation of C-aminoazoles with 2,5-dimethylhexane-2,5-diol

Alkylation of 5-aminotetrazole with 2,5-dimethylhexane-2,5-diol in perchloric acid was found to proceed on an endocyclic nitrogen atom as well as on the amino group, giving 5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-4H-tetrazolo[1,5-a][1,3]diazepine. Under analogous conditions, 3-amino-1,2,4-triazole undergoes cycloalkylation of the neighboring N1 and N2 atoms of the heterocycle resulting in 1-amino-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-[1,2,4]triazolo[1,2-a]pyridazinium perchlorate. The crystal structures of the products were determined by single crystal X-ray analysis.     

Synthesis and Spectral Characterization of Some Transition Metal Complexes Containing Pentadentate SNNNS Donor Heterocyclic Schiff Base Ligands

A new Schiff base, 2,6-diacetylpyridine bis(3-methylsulfhydryl-4-amino-5-mercapto-1,2,4-triazole) (DPMAMT) is designed and synthesized by the condensation of 2,6-diacetylpyridine with 3-methylsulfhydryl-4-amino-5-mercapto-1,2,4-triazole, and structurally characterized. Copper(II), cobalt(II), nickel(II), manganese(II), zinc(II), cadmium(II) and oxovanadium(IV) complexes of DPMAMT have been prepared for the first time, and characterized on the basis of elemental analyses, conductance measurements, magnetic properties, spectral (i.r., ¹H-n.m.r., u.v.–vis., e.p.r. and FAB-mass) and thermal studies. The complexes exhibit an octahedral geometry around the metal center. The pentadentate behavior of the ligand was confirmed on the basis of spectral studies.     

Investigation of the iron(II) complex of bis-3,3'-(5,6-dimethyl-1,2,4-triazine)

The reagent, bis-3,3'-(5,6-dimethyl-1,2,4-triazine) (BDMT), forms intensely colored complexes with selected transition metal ions. The reagent is water-soluble and easily prepared. An intense orange complex, Fe(BDMT)₃²⁺;is formed on reaction of iron(II) with the reagent in aqueous solution at pH 4.0–7.0. Nuclear magnetic resonance data show that chelation occurs between the 2,2'-nitrogens of the reagent. The complex exhibits absorption maxima at 408 mμ, with molar absorptivities of 12,000 and 15,000 respectively. The perchlorate salt of the complex is readily extracted into nitrobenzene. A proposed spectrophotometric method for the determination of iron is both accurate and precis     

Kinetic and mechanistic studies on the oxidation of hydroxylamine, semicarbazide, and thiosemicarbazide by iron(III) in the presence of triazines

In the presence of 3-(2-pyridyl)-5,6-bis(4-phenyl-sulphonicacid)-1,2,4-triazine disodium salt (PDTS), 3-(4-(4-phenylsulphonic-acid)-2-pyridyl)-5,6-bis(4-phenylsulphonic-acid)-1,2,4-triazine trisodium salt (PPDTS), or 2,4-bis(5,6-bis(4-phenylsulphonic-acid)-1,2,4-triazin-3-yl)pyridine tetra sodium salt (BDTPS), iron(III) oxidizes hydroxylamine to nitrogen gas, semicarbazide to CO₂ and NH₃ and thiosemicarbazide to a disulfide. The corresponding iron product is the 1:3 complex of iron(II) and PDTS, PPDTS, or BDTPS. The kinetics of these reactions was studied by monitoring the iron(II) product by conventional spectrophotometry. The reaction is first order in iron(III). Kinetic evidence was obtained for the formation of 1:1:2 ternary complexes of iron(III), substrate, and sulfonated triazine. Evidence for the ternary intermediate complexes was obtained by ion-exchange studies using ⁵⁹Fe-labeled iron(III) solutions. The dissociation of the ternary complex is identified as the rate-determining step.     

Trapping an Unexpected/Unprecedented Hexanuclear Ce(III) Hydrolysis Product with Neutral 4-Amino-1,2,4-triazole

Using Ce(III) as both a representative lanthanide and actinide analog, the ability of mixtures of acidic and basic azoles to allow direct access to homoleptic N-donor f-element complexes in one pot reactions from hydrated salts as starting materials was examined by reacting mixtures of 4-amino-1,2,4-triazole (4-NH₂-1,2,4-Triaz), 5-amino-tetrazole (5-NH₂-HTetaz), and 1,2,3-triazole (1,2,3-HTriaz) in 1 : 1 and 1 : 3 ratios with CeCl₃ ⋅ 7H₂O, [C₂mim]₃[CeCl₆] ([C₂mim]⁺=1-ethyl-2-methylimidazolium), and Ce(NO₃)₃ ⋅ 6H₂O. Although unsuccessful in our goal, structural analysis revealed that neutral 4-NH₂-1,2,4-Triaz is structure directing via η²μ₂κ² bridging, with the formation of the dinuclear complexes [Ce₂Cl₂(μ₂-4-NH₂-1,2,4-Triaz)₄(H₂O)₈]Cl₄ ⋅ 4H₂O, [Ce₂(μ₂-4-NH₂-1,2,4-Triaz)₄(4-NH₂-1,2,4-Triaz)₂(Cl)₆], and [4-NH₂-1,2,4-HTriaz][Ce₂(μ₂-4-NH₂-1,2,4-Triaz)₂(μ₂-NO₃)(NO₃)₆(H₂O)₂]. When the synthetic conditions favored hydrolysis, the hexanuclear Ce(III) complex [Ce₆(μ₃-O)₄(μ₃-OH)₂(μ₃-Cl)₂(Cl)₆(μ₂-4-NH₂-1,2,4-Triaz)₁₂] ⋅ 7H₂O was isolated. This unexpected hydrolysis product represents the first example of a high nuclearity lanthanide complex where all Ln atoms are pairwise connected through 12 N-donor ligands or 12 neutral bridging ligands of any type, a rare example of incorporation of non-oxo coordinating anions in the M₆X₈ core, and the first reported Ce(III) hexanuclear complex of this type.     

Synthetic and spectroscopic study of 5-amino-2-acyl-1,2,4-thiadiazolin-3-ones

5-Amino-2-acyl-1,2,4-thiadiazolin-3-ones 2–1 can be synthesized from 5-amino-2H-1,2,4-thiadiazolin-3-one ( 1–1 ) via a selective acylation with an acid anhydride in pyridine. The ¹H nmr spectral characteristics of 5-amino-2-acyl-1,2,4-thiadiazolin-3-ones 2–1 is in particular, compared with 5-amino-2H-1,2,4-thiadiazolin-3-one ( 1–1 ) and 5-amino-2-alkyl-1,2,4-thiadiazolin-3-ones 1–2, 1–3 . The 5-amino group of 2–1 appeared as two peaks in its ¹H nmr spectrum, which merged to a single peak at a higher temperature, while those of compound 1–1, 1–2 and 1–3 appear only as a single peak. The restricted rotation of the C(5)-N(5) (at amino) bond of 5-amino-2-acetyl-1,2,4-thiadiazolin-3-one (2a-1) is about 14.5 Kcal/mol.     

Biomimetic oxidation of metribuzin with hydrogen peroxide catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides

The biomimetic oxidation of metribuzin, a pre- and post-emergence herbicide with hydrogen peroxide catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides [TAPFe(III)Cl], has been studied yielding 6-t-butyl-3-methylthio-1,2,4-triazine-5(4H)-one, 4-amino-6-t-butyl-3,5(2H,4H)-dione and 6-t-butyl-1,2,4-triazin-3,5(2H,4H)-dione under various reaction conditions.