RESOLUTION OF RACEMIC MIXTURES OF CHIRAL ARENECHROMIUMTRICARBONYL COMPLEXES USING A BAKERBOND-CHIRALCEL HPLC COLUMN

Racemic mixtures of eight new chiral arenechromiumtricarbonyl complexe s were prepared and fully characterized by IR, H-1 and C-13 NMR spectr oscopy, mass spectrometry and elemental analysis. These compounds, alo ng with 25 previously reported chiral complexes were used to establish the ability of commercially available chiral HPLC columns to effect r esolution of the mixtures. It was found that Bakerbond Chiralcel OD(R) columns, consisting of derivatized cellulose on silica gel, successfu lly resolve racemic mixtures of most arene complexes with good to exce llent results. Some tentative patterns in the effect of functional gro ups and ring substitution on the separation efficiency have been ident ified and are discussed. Direct resolution of complex 22, ethyl-ortho- methoxybenzoate Cr(CO)(3), was performed on the semipreparative scale. The resolved enantiomers were characterized by optical rotation measu rements and gave the following data: band 1, t(R'1) = 77.8 min, [alpha ](21)(589) = +/- 30.0 +/- 4.1 degrees; band 2, t(R'2) = 179.8 min, [al pha](21)(589) = -29.5 +/- 1.0 degrees.