Kinetic Studies of Fast Equilibrium by Means of High-performance Liquid Chromatography. III. Ternary Complex Formation between Ni(II) Diethyldithiocarbamate and Other Unlike Ni(II) Chelates

The labile ternary complex formation (MA2+MB22MAB with K=[MAB]2/([MA2][MB2])) between Ni(II) diethyldithiocarbamate(MA2) and other several Ni(II) chelates(MB2) was investigated by high-performance liquid chromatography; two solutions of MA2 and MB2 were mixed and equilibrated. The tendency to form a ternary complex is summarized as follows: (1) no ternary complex formation takes place (B=dimethylglyoxime and 1-(2-pyridylazo)-2-naphthol), for which high structural stability of binary complex MB2 is responsible; (2) the ternary complex formation is controlled statistically (K=4.0), suggesting the absence of any factor to stabilize or unstabilize the ternary complex (B=N,N-disubstituted dithiocarbamates and N-monosubstituted dithiocarbamates); (3) the ternary complex formation is favored (K>4.0) (B=xanthates); and (4) all initial binary complexes are converted into a very stable species which is possibly a ternary complex (B=dithizone). Kinetic characteristics of these ternary complex formations are examined.