THE CRYSTAL AND MOLECULAR-STRUCTURE OF AN ASYMMETRIC DIACETYLENE MONOMER, 6-(2-METHYL-4-NITROANILINO)-2,4-HEXADIYN-1-OL

The crystal and molecular structure of an asymmetric diacetylene monom er has been determined from x-ray diffraction data. The crystals, obta ined from an acetone/pentane solution, are orthorhombic, Fdd2 with Z = 16 in a unit cell having dimensions of a = 42,815(6) angstrom, b = 22 ,224(5) angstrom, c = 4,996(1) angstrom. The structure was solved by d irect methods and refined by least-squares techniques to an R(F) of 6, 4 % for 988 reflections and 171 variables. The diacetylene chains are disposed in the unit cell in a complex manner in order to satisfy the hydrogen-bonding, crystal packing, and symmetry requirements of the sy stem. The solid state polymerization mechanism is discussed with respe ct to the geometric disposition of the diacetylene chains. These chain s are far apart and incorrectly oriented with respect to each other to permit polymerization in the crystal by means of 1,4-addition, consis tent with the Baughman mechanistic model.