Crystal and molecular structures of (–)-7,7′-dibromo-3,3,3′,3′,5,5′hexamethyl-1,1′-spirobi-indane-6,6′-diol and (±)-3,3,3′,3′,5,5′-hexamethyl-1,1′-spirobi-indane

Abstract

The crystal structures of (–)-7,7′-dibromo-3,3,3′,3′,5,5′-hexamethvl-1,1′-spirobi-indane-6,6′-diol (I) and (±)3,3,3′,3′,5,5′-hexamethyl-1,1′-spirobi-indane (II) have been determined [by the heavy-atom method for (I) and direct methods for (II)] from X-ray diffractometer data. Crystals of (I) are orthorhombic, space group P2₁2₁2₁, a= 19.625(2), b= 7.644(1), c= 14.021 (2)Å, Z= 4. Crystals of (II) are monoclinic, space group C2/c, a= 21.699(2), b= 14.222(1), c= 6.173(1)Å, β= 97.78(1)°, Z= 4 (the molecules lie at the two-fold axes in the crystal). The structures were refined by a block-diagonal least-squares method to R, 0.083 for (I)(1 244 reflections) and 0.066 for (II)(974 reflections). The cyclopentene rings are in the envelope conformation in (I) and (II). The dihedral angle between the two benzene ring planes is 81 (I) and 75.5°(II). The absolute configuration of (I) indicates that the molecule has the (R)-configuration.