Crystal and Molecular Structure of 3,3′-Sulphur-bis [methyl 4-(4-methyl-benzoyloxy)-benzoate as a Model Compound of Sulphur Ligated Siamese Twin Mesogens

Abstract

In order to enlighten the molecular structure of sulphur ligated Siamese twin mesogens we were interested in X-ray crystal structure determinations of such substances. Single crystals suitable for X-ray investigations couldn't be obtained of the mesogenic sulphinyl and sulphonyl ligated twins but of the nonmesogenic sulphide (CH₃‒C₆H₄‒CO(O)‒C₆H₃‒CO(O)‒CH₃)₂S 2 which can be used as a model for the just-mentioned mesogens.

The title compound 2 crystallizes in the monoclinic space group C2/c with a = 10.703(2), b = 9.374(1), c = 29.206(5), Å, β = 111.49(1)° and four molecules per unit cell. The structure was solved by direct methods and refined to R = 0.044. The molecules have exact C₂ symmetry and a gabled roof-like shape. The two halves of one twin molecule adopt each a fully stretched and nearly linear conformation and are antiparallel oriented to each other.

Key Words:

• Sulphur ligated twins
• Siamese twin mesogens
• molecular structure
• crystal structure
• X-ray analysis