STRUCTURE AND REACTIVITY IN OCTAHEDRAL COMPLEXES .X. STEPWISE HYDROLYSIS OF CIS-DIACETATOBIS(ALPHA,ALPHA'-DIPYRIDYL)COBALT(3) ION

The hydrolysis of the cis-diacetatobis(α,α′-dipyridyl)cobalt(III) ion has been investigated over the pH range of 2-12. First-order kinetics were obtained throughout, with the exception of the lower end of the range where the contribution of an acid-catalysis term becomes important for the reaction of the first acetato ligand of the diacetato complex. In contrast, there is found no evidence of hydroxide ion catalysis. Essential rate data were also obtained for the intermediate product of the reaction, the cis-aquoacetato complex. The reactions are believed to result from a dissociation mechanism of aquation of the diacetato, aquoacetato, or hydroxoacetato species and, in the case of more acidic conditions, of the protonated species of the diacetato complex. With reference to the more basic conditions, the results are taken as a test for the validity of the SN1 CB mechanism for the base hydrolysis of N-H-containing Co (III) octahedral complexes. © 1968, American Chemical Society. All rights reserved.