DETERMINATION OF THE ABSOLUTE CONFIGURATIONS OF 1,2-DIPHOSPHINYLETHANES AND 1,2-DIPHOSPHINYLETHENES POSSESSING TWO NONEQUIVALENT ASYMMETRIC PHOSPHORUS CENTRES. CRYSTAL STRUCTURE OF (R,S)-1-(tert-BUTYLPHENYLPHOSPHINYL)-2-(METHYL- PHENYLPHOSPHINYL)ETHANE.¹

Abstract

Using single-crystal X-ray diffraction technique the R, S configuration has been assigned to a homochiral (-)-1-tert-butylphenylphosphinyl-2-methylphenylphosphinylethane. This has allowed the assignment of absolute configuration also to its P1-epimer as well as, through chemical correlation, to the two epimeric trans-1-tert-butylphenylphosphinyl-2- methylphenylphosphinylethenes. Attempted correlation of absolute configurations of the assigned compounds with their spectral and physical features holds some promise as a diagnostic tool for future distinction of epimeric P-chiral 1,2-diphosphinylethanes and 1,2-diphosphinylethenes possessing similar aryl alkyl substitution pattern at phosphorus.

Key Words:

• 1,2-Diphosphinylethanes
• 1,2-diphosphinylethenes
• enantiomeric
• configuration
• X-ray
• hydrogenation