VOLUME OF ACTIVATION AND REACTIVITY OF THE CONJUGATE BASE OF COBALT(III) AMINE COMPLEXES

A model inferred from features of the ammoniation of cobalt(III) haloamines is extended to base hydrolysis in aqueous solution. This model connects the reactivity of the conjugate base to a large volume increase on passing to the transition state in a limiting dissociative mode. A comparison with experimental results shows good agreement for the compounds Co(NH3)5Xn+, with X=F, Cl, NO3, PO4, or SO4, whereas compounds with X=N3 and NCS do not comply and the compound with X=Br is ambiguous. The relation between the change in structure of the second coordination sphere on activation and the specific properties of the electrostatic field of the Co3+ ion is examined. © 1979, American Chemical Society. All rights reserved.