Perihan GÜRKAN

Potentiometric determination of protonation constants of some new azo dyes and stability constants of their Ni(II) complexes

Dört yeni azo boyarmaddesinin protonlanma sabitleri ile ML ve ML2 tipindeki komplekslerin kararlılık sabitleri hacimce %60'lık etanol-su ortamında 25 ±0,1° C ve 50 ±0,1° C de potansiyometrik olarak belirlendi. Termodinamik parametreler $Delta G$ ve $Delta H$ hesaplandı. Azo boyarmaddeleri için, moleküldeki azo grubunun ve fenolik oksijenin protonlanmasına karşılık gelen, iki protonlanma sabiti bulundu. Proton-ligand ve metal-ligand kararlılık sabitleri beklendiği gibi sıcaklığın artmasıyla azaldı. Bütün kompleksler için negatif olan AG ve A/f değerleri kompleksleşme tepkimesinin ekzotermik ve istemli olduğunu gösterdi.

Bazı yeni azo boyarmaddelerinin protonlanma sabitleri ile Ni(II) komplekslerinin kararlılık sabitlerinin potansiyometrik olarak belirlenmesi

Protonation constants of four new azo dyes and stability constants of their ML and ML2 type Ni(II) complexes were determined by potentiometrically in ethanol-water solution (60%, v/v) at 25 ±0,1° C and 50 ±0,1° C and $mu$ = 0,1 M KCI. Thermodynamic parameters$Delta G$ ve $Delta H$ were calculated. Two protonation constants were found for all the azo dyes corresponding to the protonation of the azo group and the pheonolic oxygen in the molecule. The proton-ligand and metal-ligand stability constants decreased with increasing temperature, as expected. The negative$Delta G$ ve $Delta H$ values of all the complexes indicated spontaneously and exothermic nature of the complexation reactions.

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