A refinement of the structure of meso-3,3'-di-(p-chlorophenyl)bi-3-phthalidyl

Abstract

The structure of meso-3,3'-di(p-chlorophenyl)bi-3-phthalidyl has been refined from three-dimensional X-ray data by full-matrix least-squares methods to an R index of 0.009 for 912 observed reflexions. The compound crystallizes in the triclinic space group PI̅, with a monomolecular cell of dimensions a= 7.89, b = 8.06, c = 9.65 Å, α = 86°18', β = 99°18' and γ = 105°44'. The two halves of molecule are related by a centre of symmetry and in each half the phenyl ring is tilted with respect to the phthalidyl ring system by 124°53'. The lactone group is planar and exhibits the expected symmetry of the C-O bonds. The thermal parameters of the atom have been qualitatively explained in terms of rigid-body oscillations about the single bond connecting the two halves of the molecule and that connecting the phenyl ring to the phthalidyl ring. The structure can be described as consisting of close-packed layers of molecules in the (100) plane repeated periodically along the crystallographic X direction. The molecular coordination number in this arragement is 12 and the packing coefficient 0.68.