STEREOCHEMISTRY OF BASE HYDROLYSIS OF CO(NH3)5X2+ AND CO(EN)2LXN+ IONS

The stereochemistry of base hydrolysis of Co(NH3)5X2+ and Co(en)2LXn+ complexes is examined in terms of the Sn1CB mechanism. Stereochemical results reported for the [Co(NH3)4(15NH3)X]2+ complexes support the conclusion that the leaving group, X-, leaves from a position cis to an amido group to form a trigonal-bipyramidal intermediate and that H2O enters the intermediate by the microscopic reverse of this process. It is argued that for the base hydrolysis reactions of Co(en)2LXn+ complexes only two of a possible four (or three of a possible five where L = NH3) trigonal-bipyramidal intermediates will be important. Assuming that only these two intermediates are important, the retention of optical activity in the base hydrolysis of active cis-Co(en)2LXn+ can be predicted from the yield of trans product from cis- and from trans- Co(en)2LXn+. © 1969, American Chemical Society. All rights reserved.