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Article info. : 2006; 3(3) (pp 247~252)

 

Donor Ligand, Basal Ligand and Solvent Effects on the Equilibrium Constants of Triphenylphosphinecobalt(III) Schiff Base Complexes with Phosphite Ligands

M. Asadi a,*, K. Mohammadib and A.H. Kiyanfarc

aChemistry Department, College of Sciences, Shiraz University, Shiraz 71454, I.R. Iran
bChemistry Department, Faculty of Sciences, Persian Gulf University, Bushehr 75169, I.R. Iran
cChemistry Department, College of Sciences, Kurdestan University, Sanandaje, I.R. Iran

(Received 22 April 2006, Accepted 17 May 2006)

The equilibrium constants and the thermodynamic parameters were spectrophotometrically measured for the 1:1 adduct formation of [Co(Salen)(PPh3)]ClO4.H2O, and [Co(7,7-Me2Salen)(PPh3)]ClO4.H2O as acceptors, with P(OR)3 (R = methyl, ethyl , and i-propyl) as donors, in acetonitrile (CH3CN) and dimethylformamide (DMF) as solvents at constant ionic strength (I = 0.1 M NaClO4), and various temperatures (t = 10-50 C). Our results revealed the following trends: stability of the cobalt(III) Schiff base complexes toward a given phosphite donor, [Co(7,7'-Me2Salen)(PPh3)]+ < [Co(Salen)(PPh3)]+; binding of the donors (phosphites) toward a given cobalt(ΙΙΙ) Schiff base complex, P(OEt)3 > P(OMe)3 > P(O-iPr)3; influence of solvent on the stability of a given cobalt(III) Schiff base complex toward a given phosphite donor, CH3CN < DMF.

Keywords: Schiff base, Thermodynamic parameter, Equilibrium constant, Phosphine, Cobalt complex

 

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