Cobalt(III) complexes with racemic polyamine ligands 1. Isomers formed using 5,5,7(R,S),12,12,12,14(R,S)-hexamethyl-1,4,8,11-tetraazacyclotetradecane (tetb)

Abstract

cis-[Co(ox)(tetb]ClO4 is readily isolated from the reaction between tetb (tetb = rac-Me6-cyclam = 5,5,7(R,S),12,12,14(R,S)-hexamethyl-1,4,8,11-tetraazacyclotetradecane) and K3Co(ox)3·3H2O in aqueous solution. Removal of the coordinated oxalato ligand by acid hydrolysis (with HCl/HClO4) results in the formation of α-trans-(RRRR,SSSS), [CoCl2{(SSeq,RReq)-tetb}]ClO4 with both six-membered rings in the twist conformation. The (RR)-(+)-tartrate (-2) ion coordinates enantioselectively with this isomer to give (-)-cis-[Co2{μ-(RR)-(+)-(tart)}{(RR)-tetb}2](ClO4)2 and this, in turn, reacts with HCl/HClO4 to give (-)-α-trans-(1S,4S,8S,11S)-[CoCl12{7Req,14Req)-tetb}]ClO4. The absolute configuration of the tetraamine obtained in the resolution procedure was established by synthesizing the α-trans-dichloro isomer using tetb of known absolute configuration. © 1988.