Kinetics of formation and stability constants of some pentacyanoferrate(II) complexes of aromatic nitrogen heterocycles

Toma, Henrique E.; Malin, John M.

doi:10.1021/ic50127a026

Cited by 116 publications

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“…[6], previously proposed by Shain and lated value for the isomerization constant K is 1.9 * 0.3 at Nicholson ( I I) for the case of a reversible electrochemical 33"C, in agreement with the results from 13C nmr. process preceded by a chemical reaction.…”

Section: Methodssupporting

confidence: 89%

“…The electrochemical behavior of the benzotriazole comid plexes was investigated using cyclic voltammetry. The mea- [6] = 1.02 + -surements were carried out in aqueous solutions at pH 4.5 (lo-' M acetate buffer) in the presence of 0.100 M ~d 1 , and at least ten times excess of free ligand to prevent the dissociation of the complexes. Typical cyclic voltammograms of the benzotriazole complexes are shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…[6], i is the observed current, and id is the diffusion controlled current calculated from the data in the absence of chemical reactions, or at low scan rates.…”

Section: Methodsmentioning

confidence: 99%

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Spectroscopic and electrochemical studies on linkage isomerism in iron(II) complexes of benzotriazole, a corrosion inhibitor

Toma¹,

Giesbrecht²,

Rojas³

1983

Can. J. Chem.

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. Can. J . Chcm. 61, 2520Chcm. 61, (1983.Benzotriazolc reacts with the aquapcntacyanoferrate(I1) complex, at pH 4.5, producing a mixture of N-coordinated isomers.Characterization based on 'H and "C nmr spcctroscopy yielded an equilibrium constant K = 1.9 + 0.3, favoring the less symmetric N 1-isomer. Two reversible peaks of oxidation. corresponding to the N I and N2 isomers, were observed in the cyclic voltammograms at high scan rates, with Ellz = 0.43 and 0.53 V versus NHE, respectively. The cyclic voltam~nograms at intermediate scan rates were successfully analysed in terms of an isomerization reaction preceding reversible charge-transfer. The kinetic constants of isomerization, kr and kh, were 1.5 and 0.65 s-I, respectively. The limiting dissociative rates, k-L = 5.3 x 10-' s-', measured in the presence of dimethyl sulfoxide, support an intramolecular mechanism for the isomerization reaction.HENRIQUE E. TOMA, ERNESTO GIESBRECHT et RAMON L. ESPINOZA ROJAS. Can. J . Chem. 61, 2520Chem. 61, (1983.Le benzotriazole rCagit avec le complexe F~(CN)~H?O'-h pH 4,5, en produqant une melange des isomeres coordonnCs au Nitrogene. L'equilibre de cette reaction, avec K = 1,9 t-0.3 cn faveur de le NI-isomere, a CtC montrCe par la Spectroscopique 'H et I3C nmr, dans D20. 11 est possible de voir deux pics correspondents a la oxydation des N1 et N2 isomeres, avec E l / ? = 0,43 et 0,53 V versus ENH, dans les voltamogrammes cycliques 3. vClocitCs de balayage plus vite. L'examen thCorique des voltamogrammes cycliques dans conditions de velocitC de balayage intermkdes, a montree une reaction de isomeritation prCcCdent le transfkrement reversible dcs electrons. Les constants cinCtiques de la isomeritation, k, et khr ont CtC calculees comme 1,5 et 0.65 s -' , respectivement. Les constants de substitution limite, k-L = 5.3 x 10-' s-I, obtenus dans la prCsence de dimethyl sulfoxyde, permettent proposer un mechanisme intramolCculaire pour la reaction de isomeritation.

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Section: Methodssupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

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Spectroscopic and electrochemical studies on linkage isomerism in iron(II) complexes of benzotriazole, a corrosion inhibitor

Toma¹,

Giesbrecht²,

Rojas³

1983

Can. J. Chem.

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“…[3,4,[37][38][39] These values are in excellent agreement with those previously published. [40,41] Figure 3 displays the typical trends observed for the values of k obs with excess concentration of the different compounds involved. Data were fit to Equation (1) [41] The full set of experiments indicated in Figure 3 (a) [53,55] www.eurjic.orgBy using Equation (1), the values of the limiting electrontransfer rate constants, k et , can be derived for all the systems, as well as those of the outer-sphere encounter complex association, K OS .…”

Section: Introductionmentioning

confidence: 99%

Outer‐Sphere Redox Reactions Leading to the Formation of Discrete Co^III/Fe^II Pyrazine‐Bridged Mixed‐Valence Compounds

2010

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“…The formation of substituted F~( C N )~L~-complexes from the aqua species (eq. [I]) has been shown to follow an ion-pair dissociative mechanism (2)(3)(4)(5), with a dependence of kf on the charge of the entering ligand.…”

Section: Introductionmentioning

confidence: 99%

Ligand substitution reactions of pentacyanoferrate(II) complexes with N-heterocyclic cations in aqueous solution

Macartney¹,

Warrack²

1989

Can. J. Chem.

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This paper is dedicated to Professor Ronald J. Gillespie on the occasion of his 65th birthday DONAL HUGH MACARTNEY and LAUREN JEAN WARRACK. Can. J. Chem. 67, 1774 (1989). Kinetic and spectroscopic studies have been carried out in aqueous solution on the formation (from F~( c N )~O H~' -) and dissociation of pentacyanoferrate(I1) complexes containing 1-(4-pyridy1)pyridinium and the neutral, protonated, and N-methylated forms of 4,4'-bipyridine (BPY), 1,2-bis(4-pyridy1)ethane (BPA), and trans-l,2-bis(4-pyridy1)ethylene (BPE). The pH dependences of the formation kinetics have been analyzed in terms of the specific rate and acid dissociation constants for these ligands. The rate constants (25.0°C, I = 0.10 M) for the formation of the dinuclear complexes ( N C )~F~L F~( C N )~~-have been determined for BPY (50 M-' s-I), BPA (66 M-' s-), BPE (95 M-' s-I), and pyrazine (10 M-I S-I), and are compared with the respective rate constants for the formation of (NC)5FeLCo(NH3)5. The relationships between the formation rate constants and the size of the ligand, the number of donor sites, and the magnitude and position of charges on the ligand are discussed in terms of an ion-pair dissociative mechanism.

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Kinetics of formation and stability constants of some pentacyanoferrate(II) complexes of aromatic nitrogen heterocycles

Cited by 116 publications

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Spectroscopic and electrochemical studies on linkage isomerism in iron(II) complexes of benzotriazole, a corrosion inhibitor

Spectroscopic and electrochemical studies on linkage isomerism in iron(II) complexes of benzotriazole, a corrosion inhibitor

Outer‐Sphere Redox Reactions Leading to the Formation of Discrete Co^III/Fe^II Pyrazine‐Bridged Mixed‐Valence Compounds

Ligand substitution reactions of pentacyanoferrate(II) complexes with N-heterocyclic cations in aqueous solution

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Kinetics of formation and stability constants of some pentacyanoferrate(II) complexes of aromatic nitrogen heterocycles

Cited by 116 publications

References 0 publications

Spectroscopic and electrochemical studies on linkage isomerism in iron(II) complexes of benzotriazole, a corrosion inhibitor

Spectroscopic and electrochemical studies on linkage isomerism in iron(II) complexes of benzotriazole, a corrosion inhibitor

Outer‐Sphere Redox Reactions Leading to the Formation of Discrete CoIII/FeII Pyrazine‐Bridged Mixed‐Valence Compounds

Ligand substitution reactions of pentacyanoferrate(II) complexes with N-heterocyclic cations in aqueous solution

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Outer‐Sphere Redox Reactions Leading to the Formation of Discrete Co^III/Fe^II Pyrazine‐Bridged Mixed‐Valence Compounds