Octahedral cobalt(III) complexes of the chloropentammine type. Part IV. The hydrolyses of cis-chloroallylamine- and cis-chloropropargylamine-bis(ethylenediamine)cobalt(III) cations

Abstract

Salts of the cis-chloroallylamine- and cis-chloropropargylamine-bis(ethylenediamine)cobalt(III) cations have been characterised. The first-order rate constants and the activation energies for their solvolytic aquation have been measured. Steric factors have most influence on the rate of reaction. For the allylamine complex, a unimolecular mechanism is assigned. The molecularity of the reaction with the propargylamine complex cannot be conclusively established, although activation energies make probable an S_N1 mechanism. The second-order rate constants for the hydrolysis of these cations by base have also been determined at 0° and ionic strength of 0·1M. These results are discussed in terms of an ion-pair mechanism and conclusions similar to those for the solvolytic aquation are obtained.