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. © 2010 Elsevier Ltd. All rights reserved.
