Synthesis and Study of Proton-Ligand, Metal-Ligand Stability Constants of Some 1-Aryl-3-(2-Hydroxy-5-Methylphenyl) -5-Aryl/4-Aroyl -5-Aryl-D2-Pyrazolines

S. R. Dighade¹*, M. L. Narwade¹ and M. M. Chincholkar²

¹Department of Chemistry, R.D.I.K. College, Badnera- 444 701 (India) ²Vidarbha Mahavidyalaya, Amravati- 444 604 (India)

The interactions of Cu(II) and Ni(II) metal ions with i) 3-(2-Hydroxy-5-methylphenyl)-4-benzoyl-1,5-diphenyl-D2-pyrazoline (ligand No. 1) ii) 3-(2-Hydroxy-5-methylphenyl)-5-( 4-methoxy phenyl)-1-phenyl-D2-pyrazoline (ligand No. 2) have been studied at 0.1 M ionic strength. It is observed that Cu(II) and Ni(II) metal ions form 1:1 and 1:2 complexes with L1, L2. The ligand L2 is more chelating agent than L1. The substiuted -D2-pyrazoline shows formation of stepwise complexes. The order of proton-ligand stability constant is as pK L2 is greater than pK L1. The data obtained for pK and logK are used to i) see the effect of substituents ii) check the validity of logK = a pK + b. Here proton-ligand and metal-ligand stability constants have been studied pH-metrically by Calvin-Bjerrum titration tecnique.

Proton-ligand; metal-ligand stability constants; substituted-D2-pyrazolines