Chiral Recognition In Platinum Complexes of 1,2-diphenyl-n,n'-bis[(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 diamine (mestien) have been synthetized and their stereochemistry has been investigated by H-1 and C-13 NMR spectroscopy. The molecular structure of the complex PtClMe ((E)-ClCH = CHCl) (mestien) has been determined by X-ray diffraction analysis. The coordinated nitrogen atoms display a single configuration, and a high enantioface selectivity is observed in the coordination of prochiral olefins having a moderate lateral bulk. The selectivity can be correlated to the conformation adopted by the diamine ligand, which shows a remarkable similarity to those calculated for a proposed intermediate in the enantioselective dihydroxylation of olefins by osmium tetraoxide.