The crystal and molecular structure of R-(–)-1,1′-binaphthyl: the conformational isomerism and a comparison of the chiral with the racemic packing mode

Abstract

The molecular and crystal structure of R-(–)-1,1′-binaphthyl has been determined from single-crystal X-ray data and refined by least-squares methods to R 0.045. The tetragonal crystal has unit-cell dimensions, a= 7.212 6(9), c= 27.510(5)Å, space group P4₁2₁2, and Z= 4. The molecule has a transoid conformation in the active crystal with a dihedral angle of 103° between the mean molecular planes of the two naphthalene residues. The packing modes of the molecules in the active and in the more dense (9.4%) racemic crystal are compared in connection with the spontaneous optical resolution of 1,1′-binaphthyl by crystallisation at temperatures above 76°.