Asymmetric catalysis with 7-ring chelate diphosphines: DIOP, BINAP and conformational mobility

The conformations of two classes of 7-ring diphosphine metal chelate have been analysed, based on DIOP- or BINAP-type structures. A combination of X-ray analysis, DFT calculations, data analysis based on the CDS structure database and solution NMR studies has been employed. The conformational flexibility of DIOP-type structures has been endorsed, and the scope of BINAP complex flexibility defined. BINAP complexes possess an intrinsic conformational mobility. Analysis of the metal-adjacent torsion angles C–P–M–P′ and C′–P′–M–P provides a useful probe for the ligand–metal environment, and may be more generally useful.

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((S)-2,2′-Bis(diphenylphosphino)-1,1′-binaphthyl) (1,5-cyclooctadiene) rhodium(I) tetrafluoroborateC52H44BF4P2Rh[α]D20=-42 (c 0.2, CH2Cl2)Absolute configuration: (S)