Effect of acid and ionic strength on the kinetics of electron transfer reaction of n-(2-hydroxy-ethyl) ethylenediamine-n, n’, n’-triacetatocobaltate (ii) complex with hypochlorite ion in aqueous acidic medium


  • Y. Ahmed Department of Chemistry Kano University of Science and Technology, Wudil, Kano State.
  • A. D.Onu Department of Chemistry Federal College of Education Zaria
  • S. O.Idris Department of Chemistry Ahmadu Bello University Zaria
  • S. S.Iliyasu Department of Chemistry Ahmadu Bello University Zaria
  • Y. B.Abiti Department of Chemistry Ahmadu Bello University Zaria






Aminocarboxylate, Electron Transfer Reaction, Hyphochlorite, Ionic Strength, Kinetics.


The influence of acid and ionic strength on the rate of electron transfer reaction of N-(2-hydroxy-ethyl)ethylenediamine-N,N’,N’-triacetatocobaltate(II)(hereafter, complex with Hypochlorite ion in aqueous nitric acid medium have been studied at I = 0.2 mol dm-3(NaNO3), [H+] = 1 × 10-2 mol dm-3, , T = 300 ± 1 K and λmax = 525 nm. Stoichiometric study showed 1:1 `mole ratio. The rate law derived from the kinetic study under pseudo first order condition is . The rate constant of reaction,  varies inversely with acid concentration, [H+]. The overall rate law is therefore represented as: . The reaction displayed positive salt effect which suggests the activated complex was made up of similar charged species. The reaction was catalysed by addition of formate, HCOO- and potassium, K+ ions and the Michaelis-Menten’s plot gave zero intercept indicating the absence of intermediate complex. A reaction mechanism via an outer-sphere pathway is proposed for this reaction.




[1] Anderegg, G.; Arnaud-Neu, F.; Delgado, R.; Felcman, J.; Popov, K. (2005). "Critical evaluation of stability constants of metal complexes of complexones for biomedical and environmental applications* (IUPAC Technical Report)". Pure Appl. Chem. 77 (8): 1445–1495. https://doi.org/10.1351/pac200577081445.

[2] Michihiko, K. and Sakayu, S. (1999). Cobalt proteins. European journal of Biochemistry. 261(1), 1- 9. https://doi.org/10.1046/j.1432-1327.1999.00186.x.

[3] Vuckovic, G.; Antonijevic-Nikolic, M.; Tanaskovic, S.B.; and Zivkovic-Rodovanovic, V. (2011). New Cu (II) and Co (II) octaazamacrocyclic complexes with 2-amino-3-phenylpropanoic acid. J. serb. Hem Soc. 76(5), 719 – 731. https://doi.org/10.2298/JSC101201062V.

[4] Onu, A.D., Iyun, J.F. and Idris, S.O. (2009) The Kinetics of the Reduction of Tetraoxoiodate (VII) by n-(2-Hydroxyethyl) Ethylenediaminetriacetatocobaltate(II) Ion in Aqueous Perchloric Acid. Transition Metal Chemistry, 34, 849-853. https://doi.org/10.1007/s11243-009-9273-1.

[5] Onu, A. D. (2010) Kinetics and mechanism of redox reactions of two aminocarboxylatocobaltate (II) compexes with oxy-anions and hydrogen peroxide in aqueous acidic medium. PhD. Dessetation Ahmadu Bello University Zaria, Nigeria.

[6] Onu, A.D., Iyun, J.F. and Idris, O.S. (2015) Kinetics and Stoichiometry of the Reduction of HydrogenPeroxide by an Aminocarboxylactocobaltate (II) Complex in Aqueous Medium. Open Journal of Inorganic Chemistry, 5, 75-82. https://doi.org/10.4236/ojic.2015.54009.

[7] Onu, A.D., Iyun, J.F. and Idris, S.O. (2008). Reduction reaction of [CoHEDTAOH2]- with NO2- in aqueous perchloric acid medium: Kinetics and Mechanisms, CHEMCLASS Journal Zaria.

[8] Onu, A.D., Iyun, J.F. and Idris, S.O. (2016). Oxidation of ethylenediaminetetraacetatocobaltate (II) complex by hydrogen peroxide in aqueous acidic medium: A Kinetics study, J. Chem. Soc. Nigeria, 41(2) 81 – 86.

[9] Naik, R. M., Srivastava, A., Tiwara, A. K., Yadav, S.B. S. and Verma, A. K. (2007). Kinetic and mechanism studies of amine-n-polycarboxylates complexes of cobalt (II) by periodate ions in aqueous mrdium. J. Iran. Chem. Soc., 4(1): 63 – 71. https://doi.org/10.1007/BF03245804.

[10] Naik, R.M.; Kumar, B.; Rai, J.; Rastogi, R. and Yadav S.B.S. (2010). Kinetics and mechanism of oxidation of hexamethylenediaminetetraacetatocobaltate(II) complex by periodate ion in aqueous medium. E-journal of chemistry, 7(51), 5391 – 5399. https://doi.org/10.1155/2010/180576.

[11] Mansour, A.M. (2003) Kinetics and Mechanism of the Oxidation of [N-(2-Hydroxyethyl) Ethylenediamine-N’,N’,N’-Triacetatocobalt(II) by Vanadate Ion. Transition Metal Chemistry, 28, 276-279. https://doi.org/10.1023/A:1022966528585.

[12] Mohammed, Y., Iyun, J.F. and Idris, S.O. (2010). Silver – catalyzed proxydisulphate oxidationof malachite green in aqueous acidic medium: Kinetic and mechanistic approach.International Journal of Chemistry, 20(2), 105 – 112

[13] Perumareddi, J.R., Ramachandra, V.R., Rayudu, G.V.S., Bunzli, J.C.G. and Vinny, R.S. (2003). Modern Aspects of Rare Earths and their Complexes. (1st Ed.). Burlington Elsevier. p. 38. ISBN 0080536689

[14] Abdel-Khalek, A.A., Khalil, M.M. and Khaled, E.S.H. (1993) Kinetics of Oxidation of [N-(2-hydroxyethyl)-Ethylene-Diamine-N, N’, N’-Triacetato] Cobalt (II) by N Bromosuccinimide. Transition Metal Chemistry, 18, 153-157. https://doi.org/10.1007/BF00139946.

[15] Perveen, A.; Nezemoleslam, T. and Naqvi, I.I. (2013). Preparation of cobalt(III) complexes with trans-1,2-diaminocyclohexane-N,N,N’,N’-tetraacetic acid (CDTA) and ethylenediamminetetraacetic acid (EDTA), African Journal of Pure and Applied Chemistry.7(6).218-224.

[16] Jiann-Kuo W. (1987). Kinetics of the Reduction of hypochlorite ion. Journal of Electrochemical Society Volume 134, Issue 6, 1462-1467. https://doi.org/10.1149/1.2100690.

[17] Idris, S.O., Tanimu, A., Iyun, J.F. and Mohammed, Y. (2015). Kinetics and mechanism of malachite green oxidation by hypochlorite ion in aqueous acidic medium. American Chemical Science Journal, 5(2): 185-193. https://doi.org/10.9734/ACSJ/2015/12705.

[18] Wilkins R.G. (2002): Kinetics and mechanism of reactions of transition metal complexes, 2nd Ed., Wiley-VCH Verlag GmbH &Co., pp. 65-130.

[19] Benson, D. (1969). Mechanism of inorganic reactions in solution. McGraw- Hill U.K., pp. 153.

[20] Atkins, P.W. and de Paula, J. (2002). Physical Chemistry. 7th Ed., Oxford University Press, p.962.

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