Cis,cis,cis-1,2,4,5-cyclohexanetetracarboxylic acid and its dianhydride.

cis,cis,cis-1,2,4,5-Cyclohexanetetracarboxylic acid, C(10)H(12)O(8), (I), contains a mirror plane and the cyclohexane ring exhibits a chair conformation. Two crystallographically independent hydrogen bonds form R(2)(2)(14), R(2)(2)(16) and R(4)(4)(16) ring motifs, and propagation of these two hydrogen bonds along the c and b axes generates C(2)(2)(16) and C(2)(2)(7) chains. cis,cis,cis-1,2:4,5-Cyclohexanetetracarboxylic dianhydride, C(10)H(8)O(6), (II), was prepared by the reaction of (I) with acetic anhydride. The cyclohexane ring of (II) exhibits a boat conformation and the dihedral angle between the two anhydro rings is 117.5 (1) degrees.