Bis(phosphane oxide) Adducts of Rh₂(MTPA)₄ — Kinetics and Chirality Discrimination

Abstract

Abstract The symmetrical bis(phosphane oxide) 1 and its chiral derivatives 2 and 3 form a variety of adduct species with the dirhodium complex [Rh−Rh] which can be identified by low‐temperature 1 H and 31 P NMR spectroscopy by using varying [Rh−Rh] :ligand ratios. The asymmetric bis(phosphane oxide) 3 shows a distinct preference for binding through the Ph 2 P=O (P a ) as compared to the t Bu(Ph)P=O (P b ) functionality due to the bulky tert ‐butyl group. The chiral bis(phosphane oxides) 2 and 3 form complex mixtures of various adduct species. Nevertheless, it is possible to monitor enantiomeric compositions from various NMR signal duplications at 213 K and even at room temperature or slightly elevated temperatures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)