STEREOSELECTIVITY ON ELECTRON TRANSFER REACTIONS(I); REACTION OF THE Λ-[Co(EDDS)]− AND RAC-[Co(DIAMINE)3]2+ COMPLEXES (DIAMINE = EN, CHXN)

The absolute configuration of an optically active Λ-[Co(EDDS)] − (EDDS = ethylene-diaminedisuccinate) complex was determined as Λ by the regional rule and spectroscopic data. The stereoselective ionic association between Λ-[Co(EDDS)] − and rac-[Co(en) 3 ] 3+ occurs preferentially between Λ-[Co(EDDS)] − and δ-[Co(en) 3 ] 3+ . The stereoselective electron transfer reaction between Λ-[Co(EDDS)] − and rac-[Co(en) 3 ] 2+ has been investigated in aqueous solution, DMF and DMSO. Their enantiomeric excesses (e.e.) observed are 14%, 26% and 40% of δ-[Co(en) 3 ] 3+ , respectively. The electron transfer reaction between Λ-[Co(EDDS)] − and conformationally restricted [Co(chxn) 3 ] 2+ has been examined in aqueous and DMSO solution. In aqueous solution, there are four isomers in the product which were determined as lel 3 , lel 2 ob, lelob 2 , and ob 3 of δ-[Co(chxn) 3 ] 3+ with optical purities of 22%, 25%, 11% and 10% e.e. respectively. In DMSO, the reaction produces lel 3 -δ-and lel 2 ob-δ-[Co(chxn) 3 ] 3+ with optical purities of 100% and 75% e.e. respectively.