| Research Abstract |
From the experimental studies to determine the electron-donor constant E(A) of some multidentate ligands A and the consideration on the effect of each donor atom involved in A on E(A), the following results were obtained.
1.Using monodentate pyridines as A, the coruplexation rate of Ni(II)-A 1:1 complexes with 1,10-phenantroline(phen) was studied ; and the rate constant k_<NiA>, given by d[Ni(phen)^<2+>]/dt=k_<Ni>[Ni^<2+>][phen]+ k_<NiA>[NiA][phen], was determined. With k_<NiA> thus obtained, k_<NiA>^<-H2O>(the exchange rate constant of coordinated water molucule at NiA, and E(A) of the pyridines was estimated. From these studies, it was found that the effect of hydrophobic interaction between A and phen should be taken into account for the estimation of E(A) of the pyridines.
2.Using multidentate pyridines as A, E(A) of these pyridines was estimated in the same way as monodentate pyridines. From these studies, it was found that the effective E(A) of the pyridines is given by the summation of E(X) of each donor atom X involved in A corrected for the effect of vicinal functions.
3.Using phthalic acid, anthranilic acid, o-phenylenedliamine, benzoic acid and aniline as A, the effective E(A) of these ligands is estimated. From these studies, it was found that the same discussion as on pyridines was also applicable to these aromatic ligands and with this effective E(A), the basicity constant of A (H(A)), may be estimated from the correlation logK_<NiA>=αE(A)+βH(A) where K_<NiA> refers to the formation constant of NiA, and α and β are constants characteristic of nickel(II). With the same parameers, the reasonableness of the experimental conditions of our kinetic analysis proposed previously were examined.
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