Structural studies of (2R,3R)-(+)-bis(diphenylphosphino)butane and (R)-(+)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl

The crystal structures of two chiral phosphanes, ((R,R)-chiraphos = (2R,3R)-(+)-2,3-bis(diphenylphosphino)butane and R-Tol-BINAP = (R)-(+)-2,2′-bis(di-p-tolylphosphino)-1,1′-binaphthyl) are unambiguously determined by X-ray crystallography and reported for the first time. The aim is to understand the structural characteristics and their chiral arrangement of the molecules. The (R,R)-chiraphos structure was solved in the orthorhombic space group P2₁2₁2₁ while R-Tol-BINAP was solved in the triclinic space group P1. This set of compounds demonstrates attractive intramolecular phenyl ring interactions involving two terminal phenyl rings in (R,R)-chiraphos, while a terminal tolyl ring and the central binaphthyl ring occurs in R-Tol-BINAP. The crystal structure analyses also revealed that all aromatic units have close C-H…aryl_centroid weak contacts forming continuous networks of columns and layers in (R,R)-chiraphos and R-Tol-BINAP respectively.