- Complexation of tetraphenyltetrabenzoporphine with Cu(II), Cd(II), Zn(II), and Co(II) salts in organic solvents
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The rate and activation parameters of tetraphenyltetrabenzoporphine (H 2TPTBP) complexation with 3d-metal acetates and acetylacetonates are shown to be determined by the solvent nature. With an increase in the electron-donor properties of a solvent, the reaction rate increases due to protonation of N-H bonds and decreases as MAm(Solv)n - m salt solvates become more stable. As the result, the rate of a reaction with ZnAc2 increases in the series: DMF 3CN 6H6. In inert and weakly coordinating solvents, the transition state of a reaction is supposed to be formed according to the mechanism of contraction of the salt coordination sphere. The rate of H2TPTBP reaction with metal acetates in pyridine changes in the series: Cu(II) > Cd(II) > Zn(II) > Co(II), while the stability of the obtained complexes decreases in the series Cu(II) > Co(II) > Zn(II) > Cd(II). It is shown that the spectral criterion of the complex stability can be used in the series of metal complexes with one ligand, but it is violated if the ligand structure is changed.
- Berezin,Toldina
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- Copper(II), cobalt(II), cobalt(III), and tin(IV) 5,10,15,20-tetraphenyl tetrabenzoporphyrinates: Synthesis and properties
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The complexation reactions of 5,10,15,20-tetraphenyl tetrabenzoporphyrin and the metal exchange reactions of its cadmium(II) complex with copper(II), cobalt(II), and tin(II) acetates and chlorides in a chloroform–methanol mixture and dimethylformamide were studied spectrophotometrically. Corresponding copper(II), cobalt(II), cobalt(II), and tin(IV) porphyrinates were synthesized and identified.
- Chizhova,Mal’tseva,Zav’yalov,Mamardashvili, N. Zh.
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p. 683 - 687
(2017/06/09)
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- Cobalt Tetrabutano- and Tetrabenzotetraarylporphyrin Complexes: Effect of Substituents on the Electrochemical Properties and Catalytic Activity of Oxygen Reduction Reactions
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Three series of cobalt tetraarylporphyrins were synthesized and characterized by electrochemistry and spectroelectrochemistry. The investigated compounds have the general formula (TpYPP)Co, butano(TpYPP)CoII, and benzo(TpYPP)CoII, where TpYPP represents the dianion of the meso-substituted porphyrin, Y is a CH3, H, or Cl substituent on the para position of the four phenyl rings, and butano and benzo are respectively the β- and β′-substituted groups on the four pyrrole rings of the compound. Each porphyrin undergoes one or two reductions depending upon the meso substituent and solvent utilized. Two irreversible reductions are observed for (TpYPP)CoII and butano(TpYPP)CoII in CH2Cl2 containing 0.1 M tetra-n-butylammonium perchlorate; the first leads to the formation of a highly reactive cobalt(I) porphyrin, which can then rapidly react with a solvent to give a CoIIICH2Cl as the product. Only one reversible reduction is seen for benzo(TpYPP)CoII under the same solution conditions, and the one-electron-reduction product is assigned as a cobalt(II) porphyrin π-anion radical. Three oxidations can be observed for each examined compound in CH2Cl2. The first oxidation is metal-centered for the (TpYPP)Co and benzo(TpYPP)CoII derivatives, leading to generation of a cobalt(III) porphyrin with an intact π-ring system, but this redox process is ring-centered in the case of butano(TpYPP)CoII and gives a CoII π-cation radical product. Each porphyrin was also examined as a catalyst for oxygen reduction reactions (ORRs) when adsorbed on a graphite electrode in 1.0 M HClO4. The number of electrons transferred (n) during ORRs is 2.0 for the butano(TpYPP)CoII derivatives, consistent with only H2O2 being produced as a product for the reaction with O2. However, the reduction of O2 using the cobalt benzoporphyrins as catalysts gave n values between 2.6 and 3.1 under the same solution conditions, thus producing a mixture of H2O and H2O2 as the reduction product. This result indicates that the β and β′ substituents have a significant effect on the catalytic properties of the cobalt porphyrins for ORRs in acid media.
- Ye, Lina,Fang, Yuanyuan,Ou, Zhongping,Xue, Songlin,Kadish, Karl M.
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p. 13613 - 13626
(2017/11/15)
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- Ligand trans-effect in octahedral complexes of 3d metals and its manifestation in the synthesis of metalloporphyrins in solution
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We study features of the indicator kinetic reaction of meso (tetraphenyl)tetrabenzoporhine with cobalt(II), nickel(II), and manganese(II) acetates in electron-donating organic solvents ( N , N -dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and pyrid
- Toldina,Berezin,Berezin
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p. 1090 - 1094
(2009/12/06)
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