Molecular packing modes of acyl halides. II. The crystal and molecular structure of terephthaloyl chloride

Terephthaloyl chloride (TC1), C8H4C1202, crystallizes in space group P21/c, with a = 3.902 (3), b = 6.951 (2), c = 17.669 (3)/~,, fl = 120.52 (2) °, Z = 2. The crystal structure was determined from diffractometer data and refined to R = 0.052. The centrosymmetric molecule is planar within 0.02/~,, the molecular plane being tilted 14 ° from the bc plane. The bond lengths of the benzene ring show a slight quinonoid character. The exocyclic angles (123.5, 116.5 °) at C(2) are distorted due probably to the in-plane 1,4 CI. . .C interaction. The bond lengths in the CCOCI group are: C C 1.486 (4), C=O 1.185 (3), C-CI 1.769 (3) A. The C1...O intermolecular contact of 3.32 A is accompanied by C C I . . . O and C=O. . .CI angles of 168 and 115 ° respectively. The shortest CI...C1 and H-.O contacts are 3.72 and 2.68 /~ respectively.