Characterisation of cis-[CoCl2L]+ and two diastereoisomeric trans-[CoCl2L]+ complexes and studies of the aquation kinetics (L = C-meso-5,12-dimethyl-1,4,8,11-tetra-azacyclotetradecane)
Abstract
The complex cis-[CoCl2L]ClO4 and two diastereoisomeric trans-[CoCl2L]ClO4 complexes have been isolated and characterised (α- and β-trans isomers; L = C-meso-5,12-dimethyl-1,4,8,11-tetra-azacyclotetradecane). The two trans isomers differ in the configuration at the chiral secondary NH centres (in principle ten diastereoisomers are possible). The β-trans isomer is found in conjunction with the cis isomer and isomerisation of cis-[CoCl2L]ClO4 in hot dilute hydrochloric acid gives β-trans-[CoCl2L]+. The aquation kinetics of the three isomers have been studied over a temperature range and activation parameters determined. At 25 °C the values of kaq. are 2.4 × 10–5 s–1(α-trans), 5.5 × 10–5 s–1(β-trans), and 8.7 × 10–2 s–1(cis isomer). Configurations for the complexes are considered in detail, and their reactivities in aquation discussed.