HYDROPHOBIC CONTROL OF DIASTEREOSELECTIVITY IN THE SYNTHESIS OF DOUBLE-CHAIN SURFACTANT CO(III) COMPLEXES

A series of double-chain surfactant octahedral Co(III) complexes 1-4 h as been prepared in both water and 20:1 (v/v) ethanol-water by the rea ction of an N-alkylethylenediamine ligand (5) with sodium hexanitrocob altate(III), followed by the addition of sodium perchlorate or sodium nitrate: itro-cisoid-bis(N-alkylethylenediamine)cobalt(III) perchlorat e (1) and nitrate (3), and ro-transoid-bis(N-alkylethylenediamine)coba lt(III) perchlorate (2) and nitrate (4) (alkyl = hexyl, octyl, decyl, dodecyl, and hexadecyl). The cisoid 1(3)/transoid 2(4) diastereomer ra tio increased on going from 20:1 ethanol-water to water, in particular by a factor of approximately 5 for the octyl and dodecyl perchlorate systems and approximately 8 for the hexadecyl perchlorate system. The increase in the relative amount of cisoid 1(3) is attributed to the hy drophobic effect associated with the aggregation of ligand 5 in water.