CHELATING BEHAVIOR OF SUBSTITUTED 3-ARYLHYDRAZOPENTANE-2,4-DIONE .7. STABILITY-CONSTANTS OF CHELATES OF DIVALENT TRANSITION-METALS WITH 2(4-METHYL), 3(4-METHYL), 4(4-METHYL) AND 2-SULFONIC-(4-METHYL) PHENYLHYDRAZO-PENTANE-2,4-DIONE

The dissociation constants for 2-, 3-, 4-and 2-sulphonic (4-methyl) phenyl hydrazo acetyl acetone 1igands, as well as the stabi1ity constants for chelates of these ligands with divalent metal ions Cu(ll), N;(II), Co(ll), Mn(I1) , Zn(Ilt} and Cd(I I) , have been calculated pH-metrically. The first dissociation constant for 503 H group was foudn to be strong. The difference between the values of both pKI and pK2 for the vari ous 1 i gands were found to be small. The stability constants for chelates containing 1:1 and 2:1 ratio have been calculated and compared with the stability constants of acetyl acetone itself. These differences may be attributed to the lower basicity of the sulfonated ligands and to the different nature of the ligands. The relation between 1/2 log B (overall stability constant) of the chelate compounds and both electronegativity (Xm) and second ionization potential (2nd 1p) was discussed.

A A TAHA ,G EL INANY ,B EL SHETARY ,S A ALI ,