Conformational flexibility of palladium BINAP complexes explored by X-ray analyses and DFT studies

Several crystal structures and a theoretical DFT structure of the important catalyst (BINAP)PdCl2 (BINAP: 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) have been determined. The conformational flexibilities of the BINAP backbone and of the phenyl rings do not seem to be coupled. Two novel parameter have been introduced that define the Π–Π stacking between the phenyl and biaryl rings in systems similar to the BINAP ligand, as well as the delta angle that is sensitive to the important interaction of the exchangeable ligands of the palladium with the equatorial phenyl rings of the BINAP. Furthermore, the calculated bite angle is 3° larger than the experimentally determined bite angles.

Graphical abstractFour crystal structures and a DFT study of (BINAP)PdCl2 allow to study the conformational flexibility of the complex in the solid state and the gas phase.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A set of high-quality X-ray structures of (BINAP)PdCl2 has been determined. ► The structure of (BINAP)PdCl2 has also been calculated by DFT methods. ► The bite angle of the DFT structure is 3° larger than in the crystals structures. ► A new geometric parameter to account for an asymmetric effect has been introduced.