Stability constants and stoichiometries of chromium and zirconium carboxylates complexes calculated by four comparative methods


  • Abdalazeem Omar Department of chemistry, faculty of science, Sudan University of Science and Technology (Sudan)
  • Elmugdad Ali Department of chemistry, faculty of science, Sudan University of Science and Technology (Sudan)





Half integral method, Henderson equation, Stability constants, Excel program, activity.


Four comparative methods for determination of stoichiometries and stability constants of chromium and zirconium complexes with citric and propanoic acids were studies, in purpose to select the most accurate and sensitive method, and to compare the formation of complexes of these two transition metals. (Cr 1st transition series group 6B, Zr 2nd transition series group 4B)

Metal-ligand stability constants and stoichiometries of the above systems were determined by Calvin & Bjerrum pH-metric titration technique as adopted by Irving & Rossotti.

Four methods employed were point-wise calculation method, half integral method, linear plot method and least squares method. The result seems in a good agreement with each other and any method can represents the other.


[1] Sanjay Ubale, N.G. Palaskar, Nazahar Farooqui. 2002. Effect of temperature and media on complexation of Sm (â…¢) with 5-bromo-2-hydroxy Acetophenone. 14, (1), 99-102.

[2] Santosh, D. Deosarkar, Ashok, B. Kalambe, Vijay, J. Thakare, Shivraj, G. Wanale, Vinay, V. Hiwase. 2011. Potentiometric studies of electrolyte effects on complex equilibria of some substituted 5-(2-hydroxy phenyl) Pyrazoles. Der pharma chemic. 3, (6), 75-83.

[3] Sumer, D. Thakur, Devidas, T. Mahajan, Kamlesh, P. Munot, Rajesh D. Deshmukh, Mangesh, S. Tihile. 2011b. Metal-ligand stability constants of Th (â…¢), Sm (â…¢), Nd (â…¢) and Pr (â…¢) metal ion complexes with two mercapto-4-substituted phenyl-6-substituted phenyl prymidines at 0.1M ionic strength pH-metrically. Der pharma chem. 3, (6), 382-389.

[4] Abdulbaset, A. Zaid, Mazahar, Farooqui, D.M. Janrao. 2012. Study of stability constant of biological active molecules (drug) using potentiometric titration technique. J. of chem. boils. phys. Sc. 2, (1), 67-81.

[5] F.R.,‘Hartley, C. Burgess, R.M. Alcock.1980. Solution equilibria, first ed. John Wiley and sons, New York.

[6] Cotton and Wilkinson, 1972, advanced inorganic chemistry, 3rd edition, John wiley & sons.

[7] Boner and Pardue, 1996, Chem. Experimental science, 2nd edition, John wiley & sons Inc.



[10] Dodle Douglas, Darl H. Daniel, 1995, Concept and model of inorganic chem. 2nd edition, Xerox College united states.

[11] William L. Masterton and others, 1985, Chemical principles, 6th edition, CBS college publishing.

[12] Cary D. Christian, 1980. Analytical chemistry, John wiley and sons,Inc.

[13] Louis Meites,1981.An introduction to chemical equilibrium and kinetics, first edition, Pergamon press

[14] E-book: Gurdeep, Raj, 1986.Advance inorganic chemistry-Ⅱ, first ed. Satyendra Rastogi “Mitra†p.67.Book code : 277-12 Ninth thoroughly revised 2004Twelfth ed. 2010

[15] Minaxi, Maru, M.K. Shah. 2011. Synthesis and physic-chemical studies of some divalent transition metal complexes of 2-(2’-chloro-6’-substituted quinoliny)-1H-benzo[d]imidazole ligands. J. Chem. Res. 2, (2), 14-27.

[16] Ashwini, kumar, Ashok, Kumar, Malik. 2007. Potentiometric studies on the complexes of Cu (â…¡), Cd (â…¡), Co (â…¡), Ni (â…¡), Pb (â…¡), and Zn (â…¡) with Gabapentin. Euras. J. analy. Chem. 2, (2), 1-6.

[17] Avinash, Ramteke, Marutil, Narwade. 2013. Studies of stability constants of complexes of chlorosubstituted pyrazoles and pyrazoline with Cu (â…¡), Ni (â…¡), Co (â…¡) and Nd (â…¡) metal ions in 70% dioxane- water mixture at 0.1 ionic strength. Arch. of appl. Sc. 5, (1), 231-237.

[18] Sayyed, Hussain, Abdul Rahim, Mazahar, Farooqui. 2011. Studies of binary complexes of metal ions with mandelic acid by potentiometry. Chem. J. 02, (6), 206-209.

[19] G. V., Mane, L.P. shinde, D.G. Kolhatkar. 2011. pH-metric study of proton-ligand and metal-ligand stability constant complexes of transition and inner transition metal ions with some organic acids.Inter. J. Chemistry. 3, (2), 181-187.

[20] Anjani, Kumar, Mishra, Prem, Mohan, Mishra, Sunil, K. Misra. 2011. Equilibrium studies on bivalent transition metal chelates with biologically active schiff’s base of heterocyclic aldehydes. Ras. J. Chem. 4, (2), 303-319.

[21] F. J. C. Rossotti, H. S. Rossotti. 1955. Graphical methods for determining equilibrium constants.1- system of mononuclear complexes. Ac. chem. scandinavica. 9, 1166-1176.

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