THE OXIDATION OF [CO(EDTA)](2-) BY [CO(PHEN)(3)](3+)

[(Co(phen)(3)][(Sb(R,R)-tartrate)(2)].8H(2)O, C44H44N6O20CoSb2, crysta llizes in the trigonal space group P3(2)21 (No. 154) with Z=3, a=18.86 1(4), c=11.917(3) Angstrom and R=0.035 for 1800 reflections. The struc ture has been determined and the absolute configuration of (+)(589)-[C o(phen)(3)](ClO4)(3).2H(2)O formed from the compound by Cl-2 oxidation is confirmed as Lambda. Reduction of [Co(phen)(3)](3+) by [Co(edta)(2 -) is outer-sphere with a second-order rate constant of 9.6x10(-3) M(- 1) s(-1) at 25 degrees C and 0.10 M ionic strength. When Lambda-[Co(ph en)(3)](3+) is used as oxidant, chiral induction is observed and the [ Co(edta)](-) product shows a enantiomeric excess of 20% of the Lambda isomer. This homochiral (Lambda Lambda) preference contrasts with the heterochiral (Delta Lambda) preference found previously for reactions of [Co(edta)](2-) with [Fe(phen)(3)](3+) and [Os(phen)(3)](3+). Interp retation of the results is aided by H-1 NMR relaxation studies of the ion pair {[Co(phen)(3)](3+),[Co(edta)](-)}.