BENZOPHENONE-3,3',4,4'-TETRACARBOXYLIC ACID DIHYDRATE

The title compound, C17H10O9.2H(2)O, crystallizes in the centrosymmetr ic space group P2(1)/a but does not exhibit strong eight-membered cycl ic dimer hydrogen bonds about centers of symmetry or otherwise. A rich ly three-dimensional hydrogen-bonding network is observed, however, wh ich arises from 19 hydrogen bonds per asymmetric unit; it includes a 1 4-membered cyclic dimer about a center of symmetry and hydrogen-bondin g rings of 18 and 30 members involving the acid molecule and a water m olecule, both also about centers of symmetry. The carboxyl H and O ato ms are ordered in each of the carboxyl groups. The configuration of th e benzophenone core is quite similar to that in benzophenone itself an d the configuration of the adjacent carboxyl groups is quite similar t o that in phthalic acid and naphthalene-2,3-dicarboxylic acid.