CHIRAL RECOGNITION IN PLATINUM COMPLEXES OF S[(2,4,6-TRIMETHYLPHENYL)METHYL]-1,2-DIAMINOETHANE - STEREOSELECTIVE COORDINATION OF OLEFINS AND MOLECULAR-STRUCTURE OF A TRIGONAL BIPYRAMIDAL ADDUCT

Trigonal bipyramidal olefin-platinum complexes of the title chiral dia mine (mestien) have been synthetized and their stereochemistry has bee n investigated by H-1 and C-13 NMR spectroscopy. The molecular structu re of the complex PtClMe ((E)-ClCH = CHCl) (mestien) has been determin ed by X-ray diffraction analysis. The coordinated nitrogen atoms displ ay a single configuration, and a high enantioface selectivity is obser ved in the coordination of prochiral olefins having a moderate lateral bulk. The selectivity can be correlated to the conformation adopted b y the diamine ligand, which shows a remarkable similarity to those cal culated for a proposed intermediate in the enantioselective dihydroxyl ation of olefins by osmium tetraoxide.