D. Mallick et Gs. De, KINETICS AND MECHANISM OF AQUA LIGAND SUBSTITUTION-REACTIONS FROM CIS-DIAQUA-BIS(BIPYRIDINE)RUTHENIUM(II) ION BY PYRIDINE-2-ALDOXIME IN AQUEOUS-MEDIUM, Transition metal chemistry, 18(4), 1993, pp. 417-419
The kinetic behaviour of cis-[Ru(bipy)2(H2O)2]2+ towards the anating l
igand pyridine-2-aldoxime as a function of temperature, ligand concent
ration, substrate complex concentration and pH is reported and the rat
e expression Rate = k1k2[Ru(bipy)2(H2O)2]2+ [LL]/(k-1 + k2[LL]) is est
ablished where k1 is the water dissociation rate constant for the slow
step, k-1 is the rate constant for the aquation, k2 is the ligand-cap
turing rate constant of the five-coordinate intermediate [Ru(bipy)2(H2
O)]2+ and LL is pyridine-2-aldoxime. The reaction is pH-dependent in t
he pH range 3.65-5.50. The enthalpy and entropy of activation were obt
ained using Eyring plots. The results are in conformity with a dissoci
ative mechanism.