A TETRACHLORO GUEST IN A MOLECULAR BOX

The new lattice inclusion host exo-7, exo-15-dibromo-6,7,14,15-tetrahy dro-6,14 b:5,6-b']diquinoxaline (6) has been synthesized in three step s from bicycle[3.3.1]nonane-2,6-dione and benzofurazan oxide. It prefe rentially forms crystalline inclusion compounds with small polyhaloalk ane guest molecules, and the crystal structure of the 1,1,2,2-tetrachl oroethane compound [(C21H14N4Br2)(2).C2H2Cl4, Pbcn, a 11 . 663(2), b 1 3 . 195(3), c 27 . 444(5) Angstrom, Z 4, R 0 . 041] is described. The key characteristic of this compound is a series of molecular boxes in which the guest molecules reside. Construction of the six surrounding walls is achieved with the aromatic rings of just four host molecules, and the guest molecule occupies a fixed position within the box. The intermolecular forces resulting in formation of this novel inclusion s tructure are analysed in detail.