Optisch aktive Übergangsmetall-Komplexe CV. Faciale und meridionale Chromcarbonylphosphin-Komplexe

Abstract

The optically active, facial complex Cr(CO) 3(PP′P″) ( 1) with the tridentade ligand PP′P″ = ( R)-(+)-1,2,4-tris (diphenylphosphino)butane has been synthesized and characterized. The complex Cr(CO) 3(PP′)P″ (PP′ = ( R)-(+)-prophos, P″ = PMe 2Ph) forms two pairs of diastereomers, facial ( 3, 4) and meridional ( 5, 6), respectively, that can be separated by preparative column chromatography. Surprisingly, the CD spectra of Cr(CO) 3(PP′P″) ( 1) and the facial diastereomer of Cr(CO) 3(PP′P″ ( 3), which have the same configuration at the Cr atom, are dissimilar. The meridional configuration of the two isomers 5 and 6 of Cr(CO) 3 (PP′)PMe 2Ph is supported by the 31P and 1H NMR spectra of the optically inactive complex Cr(CO) 3(PP′)P″ (PP′ = 1-[di (4-methoxyphenyl)phosphinol-2-(diphenylphosphino)ethane P″ = PMePh 2) which forms the meridional isomers 9 and 10.