Ojala CR1, Ojala WH, Britton D, Gougoutas JZ.
Acta Crystallogr B. 1999 Aug 1;55(Pt 4):530-542.4,5-Dichlorophthalic anhydride (CPA) lies on a twofold axis in space group C2/c; the molecules pack as stacks of two-dimensional sheets. Polymorph A of 5,6-dichlorobenzfurazan 1-oxide (CBF; systematic name 5,6-dichloro-2,1,3-benzoxadiazole 1-oxide) is isomorphous with CPA with disordered CBF molecules being pseudo-isosteric with the CPA molecule. Polymorph C of CBF has similar unit-cell dimensions but the arrangement of the molecules in the cell is different. Read More