Crystal structure of (1R,2S)-1,2-bis(4-chlorophenyl)-3,8-dimethoxyacenaphthene-1,2-diol, C26H20O4Cl2, is reported and discussed from the viewpoints of characteristics in spatial organization, i.e., single molecular structures of four conformers, tetrameric aggregates, and higher ordered structures, with clarification of a classical and two non-classical hydrogen bonding interactions as the structure determining interactions. The title compound crystallizes with four independent molecules (conformers G, B, R, and Y) in the asymmetric unit. Furthermore, each independent molecule displays a meso configuration, with one 4-chlorophenyl group R and the other S. The four molecules are related by inversion center in the asymmetric unit of P-1 space group, exhibiting the number of molecules is eight, Z = 8. Single molecular structure of each conformer shows that the two benzene rings are bonded with large dihedral angles against the naphthalene plane and the two phenyl rings are oriented in the same direction with respect to the naphthalene ring plane (syn-orientation). The four conformers are classified into two groups according to overlapping feature of phenyl rings, i.e., conformers G and Y have larger slippage of the phenyl rings than conformers B and R. In the molecular packing, four conformers Y, B, R, and G are connected by classical O–H…O(H) hydrogen bonds in head-to-head fashion forming S-shaped tetramer. Tetramers composed of four conformers are stacked into columnar structure along a-axis through non-classical C–H…Cl hydrogen bonds between conformers G. The columns are linked into a sheet structure by non-classical C–H…Cl hydrogen bonds between conformers G and Y along ab-diagonal. The waved sheets are interlocked by two types of non-classical C–H… hydrogen bonds forming the stripe structure along c-axis, i.e., non-classical C–H…hydrogen bonds between conformers R and Y, and those between conformers B and G.
Key words: S-shaped tetramer composed of four conformers, pseudo-centrosymmetricity, classical hydrogen bonds, non-classical hydrogen bonds