Iodorhodium(III) tetramethylchiroporphyrin: potential reagent for chiral selection and analysis of amino compounds

The iodorhodium(III) complex of tetramethylchiroporphyrin was prepared and its X-ray structure was determined. With its single site available for coor dination of an amine group, this chiral metallohost is a convenient reagent for the chiral analysis of amino compounds by H-1 NMR. It affords a 1:1 ad duct with (R)- or (S)-2-aminopropanol, and it binds rac-2-aminopropanol wit h an enantiomeric excess of 69% (enantioselective ratio 5.5) in favour of t he (R)-enantiomer at the thermodynamic equilibrium after several days. When compared to analogous experiments with chlorocobalt(III) chiroporphyrin, t hese results show that enantiodiscrimination can be metal-dependent. (C) 20 01 Elsevier Science B.V. All rights reserved.