Proton-donor Media Research Articles

Synthesis and Dissociation Kinetics of Zinc, Copper, Cobalt, and Manganese Complexes with 2,3,7,8,12,18-Hexamethyl-5-phenyl-13,17-diethylporphin and Its Nitro-Substituted Analogs in Proton-Donor Media

Nitro-substituted 2,3,7,7,8,12,18-hexamethyl-5-phenyl-13,17-diethylporphins with nitro groups in positions 10 and 20 of the porphyrin core and in the para-position of the benzene ring have been synthesized. The structure of the obtained compounds has been confirmed by H1 NMR, UV, and IR spectroscopy as well as mass spectrometry. The kinetics of dissociation of zinc, copper, cobalt, and manganese complexes of the obtained porphyrins in proton-donor media has been studied. The stability of the porphyrin metal complexes has been related to the electronic effects of the substituents in the tetrapyrrole cycle and spatial distortion of the latter.

Kinetics of the Dissociation of Cu2+ and Co2+ Complexes of Nitro Derivatives of 5,15-Diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin in Proton-Donor Media

Copper and cobalt complexes of nitro derivatives of planar and nonplanar derivatives of 5,15-diphenyl- 3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin are synthesized and their stability in proton-donor media is investigated. It is established that the kinetic parameters of the dissociation reactions of copper and cobalt complexes of the studied porphyrins depends on the degree of deformation of the porphyrin macroring and the acceptor properties of NO2 groups.

Spectral Luminescence Properties and Stability of Zinc(II) Dipyrromethenates with Different Structures in Proton-Donor Media in the Ground and Excited Electronic States

The spectral luminescent properties of a series of zinc dipyrromethenate [Zn(dpm)2] with alkyl-, phenyl-, meso-aza-, and halogen substituents in the ligand are studied in solutions in ethanol (neutral and acidified with hydrochloric acid). The stability of the complexes in proton-donor solvents in the ground and excited states is investigated, and quantum yields of laser-induced phototransformations are measured. In a number of cases, a relationship between the photochemical stability of the investigated dipyrromethenates and their properties in proton-donor media is found and discussed.

High Pressure, Temperature, and Solvent Effects on the Rate of the Diels-Alder Reaction of Furan with N-Phenylmaleimide

The effects of temperature, solvent nature, and high pressure on the rate of the Diels-Alder reaction of furan with N-phenylmaleimide were studied. A weak acceleration of the title reaction in proton-donor media was observed in comparison to other cycloaddition and ene reactions. The volumes of activation and reaction coincided within the experimental error, in keeping with the presumed cyclic transition state.

Synthesis and properties of β-brominated metal complexes of meso-triphenylcorrole

Spectral properties and chemical stability of Mn(III), Mn(IV), Fe(III), Fe(IV), and Cu(III) complexes of β-octabromotriphenylcorrole [(β-Br)8(ms-Ph)3Cor], synthesized from β-unsubstituted compounds by their reaction with molecular bromine, were studied. Cyclic voltammetry, electron microscopy, and X-ray spectral microanalysis were used to obtain electrochemical characteristics of metal corroles M(β-Br)8(ms-Ph)3Cor and gain insight into the surface texture of active catalysts on the basis of metal corroles. The electron-acceptor β-bromine substitution in the MCor macrocycle shifts the equilibrium in electron-donor solvents to lower oxidation states of the metals and also stabilizes manganese and destabilizes copper complexes in the protondonor medium HOAc-H2SO4. The electrocatalytic activity of the complexes in the reduction of molecular oxygen depends on the nature of the ligand and increases in the order Mn ≤ Cu ≪ Fe in the case of β-octabrominated macrocycles. The character of distribution of active centers on the surface of the catalysts was established for the first time.

The state and stability of magnesium(II) complexes with azaporphyrins in the proton-donor medium

The state and stability of magnesium complexes with various azaporphyrins in the proton-donor media containing acetic acid have been studied. Kinetic parameters of the complexes dissociation have been determined, possible reactions mechanisms have been proposed.

Meso-spacer influence on properties of zinc(II) complexes with 2,3′- and 3,3′-bis(dipyrrolylmethenes)

The study and comparative analysis of spectral-luminescent characteristics (absorption and fluorescence spectra), of quantum yield, and fluorescence life time in solutions, of lability in proton-donor media, solid phase thermal stability in air oxygen and argon was carried out for binuclear zinc(II) helicates with decamethyl-substituted 2,3′- and 3,3′-bis(dipyrrolylmethenes). The influence of molecular structure features of the ligands on the physicochemical properties of helicates was discussed.

Acid-base properties of thianaphthene-annulated porphyrazine and tetra(pyrazino)porphyrazine complexes with aluminum group metals

Acid-base properties of Al(III), Ga(III), and In(III) complexes with tert-butyl-substituted thianaphthene-annulated porphyrazine and tetra(2,3-pyrazino)porphyrazine in proton-donor medium (CH2Cl2-CF3COOH) were studied by spectrophotometric titration. The concentration stability constants of the singly protonated complexes were determined. The effects of the metal nature and aromatic heterocyclic fragment on the basicity of meso-nitrogen atoms were analyzed. Negative inductive effect of the sulfur atom in the thianaphthene fragment reduces the basicity of the meso-nitrogen atoms as compared to analogous porphyrazine and phthalocyanine complexes. Acid-base transformations of the thianaphthene-annulated tetra(2,3-pyrazino)porphyrazine involve both meso-nitrogen atoms and those in the pyrazine rings.

Acid base interactions of octaphenyltetrapyrazinoporphyrazine and its complex with lutetium(III) in proton-donor media

Acid base interactions of octaphenyltetrapyrazinoporphyrazine and its complex with lutetium(III) in acetic and trifluoroacetic acid media were studied, and parameters characterizing equilibria between the acid and base forms were determined. Acid-base interactions of octaphenyltetrapyrazinoporphyrazine involve primarily nitrogen atoms in the pyrazine fragments, while its lutetium(III) complex undergoes protonation at the meso-nitrogen atoms.

Acid-base interactions of benzo-annelated porphyrazines in proton-donor media

Acid-base interactions of benzo-annelated trifluoromethylphenylporphyrazines in media based on acetic and trifluoroacetic acids were studied. The quantitative characteristics of the equilibria between acid-base species were obtained. Variation of the porphyrazine structure leads to changes not only in the macroring basicity, but also in the structure and order of formation of acidic species depending on the nature of the proton-donor medium.

Acid–Basic Properties of Al(III), Ga(III), and In(III) Complexes with Octaphenyltetraazaporphine

Al(III), Ga(III), and In(III) complexes with octaphenyltetraazaporphine and halide axial ligands of the composition [(X)MTAP] (X = F, Cl, Br) and In(III) complexes with bidentate ligands of the composition [(Y)InTAP] (Y = nitrite (NO2) and 2,3-naphthodiolate (NpO2)) were synthesized. The acid–basic properties of the complexes were studied in the proton-donor media and the concentration stability constants of the acidic forms obtained at the first protonation stage were determined. The effect of the nature of a metal and extra ligand on the basic properties of meso-nitrogen atom in macrocyclic ligand was discussed.

Stability of octaphenyltetraazaporphyrin complexes with rare earth metals in proton-donor media

The acid-base interactions and solvoprotolytic dissociation of octaphenyltetraaza-porphyrin complexes with rare earth metals are discussed. The thermodynamic and kinetic stability of the acid forms of the complexes are compared.

Europium(III), Holmium(III), and Lutecium(III) Complexes with Octaphenyltetraazaporphyrin: State and Stability in Proton-Donor Media

Acid–base interaction of holmium(III) and lutecium(III) complexes with octaphenyltetraazaporphyrin in AcOH and AcOH–benzene and AcOH–H2SO4 systems was found to involve one nitrogen meso-atom. Stability constants of the obtained acid forms are determined. Solvoprotolytic dissociation of complexes in the systems based on AcOH is studied and its mechanism is discussed.

Rhodium(III) and Iridium(III) Complexes with Octaphenyltetraazaporphine: Synthesis and Study of Their Acid Forms in Proton-Donor Media

The Rh(III) and Ir(III) complexes with octaphenyltetraazaporphine (X)MOPTAP (M = Rh, X = HSO4, OH; M = Ir, X = HSO4) are synthesized and their specific acid–base interactions in the CF3COOH–CH2Cl2 and H2SO4–CH3COOH systems are studied. The quantitative characteristics of equilibria between the acid and basic forms are obtained. The stability constants рK 1 of the first acid forms, in which one of the meso-N atom is protonated, for hydrosulfate (HSO4)MOPTAP complexes in the H2SO4–CH3COOH mixture are equal to –0.54 (Rh) and 0.0057 (Ir). The Ir complexes have more basic meso-N atoms due to more strong π-backbonding effect of coordination and, therefore, the second protonation stage (рK 2 = –4.25) could be also observed. In the CF3COOH–CH2Cl2 mixture, the basic properties of the meso-N atoms are levelled out. For (HSO4)RhOPTAP рK 1 = 1.35, while for (HSO4)IrOPTAP рK 1 = 1.24 and рK 2 = 0.45.

State and Stability of Erbium(III) and Dysprosium(III) Complexes of Octaphenyltetraazaporphine in Proton-Donor Media

The acid-base interaction of chloro(octaphenyltetraazaporphinato)erbium(III), (acetylacetonato)(octaphenyltetraazaporphinato)erbium(III), and (acetylacetonato)(octaphenyltetraazaporphinato)dysprosium(III) in AcOH and in AcOH-benzene and AcOH-H2SO4 systems involves one meso-nitrogen atom of the complexes; the stability constants of the resulting acid forms were estimated. The solvoprotolytic dissociation of the complexes in the AcOH-H2SO4 system was studied, its kinetic parameters were determined, and some suggestions as to the dissociation mechanism were made.

Kinetic Stability of Indium(III) Complexes with Azaporphyrins in Aqueous Sulfuric Acid

Stability of chloro(octaphenyltetraazaporphinato)indium(III) and chloro(2,8,12,18-tetrabutyl-3,7,13,17-tetramethyl-5,15-diazaporphinato)indium(III) in 90-98 % aqueous sulfuric acid was studied. Kinetic parameters of solvoprotolytic dissociation of the complexes were determined, and a mechanism of the reaction was proposed. Diaza substitution results in more stable complexes than tetraaza substitution. The state of chloro(2,8,12,18-tetrabutyl-3,7,13,17-tetramethyl-5,15-diazaporphinato)indium(III) in a proton-donor medium was studied to show that the acid-base interaction involves one by one two meso-nitrogen atoms. Dissociation constants of the resulting acid forms were determined.

Kinetic stability of complexes of conjugated macroheterocycles with metals in a proton-donor medium

The rate of decomposition of conjugated macroheterocyclic ligands containing isoindole and 1,2,4-thiadiazole residues has been studied together with the rate of dissociation of their complexes with copper, cobalt, and zinc in a proton-donor medium at three temperatures. Rate constants and activation parameters have been determined for the decomposition of the macrocyclic ligands and the dissociation of their complexes.

Esters of fluorine-containing ?-keto acids in the reaction with amines

1. Methyl esters of fluorine-containing α-ketoacids with methylamine, regardless of the nature of the solvent, give addition products at the α-keto group and products of aminolysis of the ester group. 2. Esters of fluorine-containing α-ketoacids react regiospecifically with diethylamine at the ester group, giving N,N-diethylamides of α-hydroxy-α-methoxyfluorocarboxylic acids in aprotic media and diethylammonium salts of fluorine-containing α,α-dihydroxyfluorocarboxylic acids in proton donor media; upon heating, the diethylammonium salts eliminate water with the formation of diethylamides.

On the problem of two-electron reduction of arenecyclopentadienyliron cations

The naphthalene-cp-iron cation (cp  cyclopentadienyl) has been studied polarographically under strictly aprotic conditions to prove the existence of the two-electron reduction product, the anion [C 10H 8FeC 5H 5] −. The reduction of the biphenyl- and benzene-cp-iron cations with sodium amalgam in proton donor media (pentane/water) is shown to yield, together with the electroneutral arene π-complexes AreneFeC 5H 5, the corresponding iron cyclohexadienyl-cp derivatives, endo-1-C 6H 5C 6H 6FeC 5H 5 and C 6H 7FeC 5H 5. The suggestion is made that the latter are formed from the two-electron reduction products, [AreneFeC 5H 5] −, under the action of protons. The [AreneFeC 5H 5] − anions cannot be detected in the reduction of [AreneFeC 5H 5] + with sodium amalgam in aprotic media as these anions react with excess [AreneFeC 5H 5] + to give two molecules of AreneFeC 5H 5.

?-Oxides in reactions with nh acids of the heterocyclic series

A number of 1-(2-hydroxyalkyl)-3,5-dichloro-1,2,4-triazoles and their derivatives were obtained by reaction of 3,5-dichloro-1,2,4-triazole with α-oxides in protondonor media in the presence of bases.