ChemInform Abstract: The Relative Nucleophilic Efficiency of Water and the Azide and Thiocyanate Ions in the Aqueous Substitution of Chloropentacyanocobaltate(III)

The kinetics of the substitution of Cl– in [Co(CN)5Cl]3– by solvent H2O and by X–= NCS– or N3– may be quantitatively interpreted by a stepwise mechanism, equations (i) and (ii). High-performance liquid chromatographic analysis confirms the absence of direct chloride substitution by reaction (iii). These results support the view that the substitution occurs by an Id interchange mechanism. [Co(CN)5Cl]3–+ H2O →[Co(CN)5(OH2)]2–+ Cl–(i)[Co(CN)5(OH2)]2–+ X–→[Co(CN)5X]3–+ H2O (ii)[Co(CN)5Cl]3–+ X–→[Co(CN)5X]3–+ Cl–(iii)