Kinetics and stereochemistry of base hydrolysis of trans- and Λ-cis-[Co(en)2(py)Cl]2+

The rates and steric course of base hydrolysis for Lambda- cis - and trans -[Co(en)(2) (py)Cl](2+) have been carefully determined. Values of k(OH) are 81+/-4 and 914+/-23 M-1 s(-1) for the cis and trans ions respectively, and both are appreciably larger than their alkylamine analogues. Thus pyridine enhances the reactivity in base, but for these particular species the effect is no more cis or trans specific than it is for other "non-displaced" ligands. The steric course, 59% trans -product from trans -reactant, and 90% cis -product from cis -reactant, is likewise not unusual, but the net activity (8.3%) for the cis -product derived from Lambda- or Delta- cis -reactant is anomalously low ( ca . 49% Lambda, 41% Delta). The results are discussed in terms of Nordmeyer's 1969 model which is reconsidered in the light of these and other new results.