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organic compounds
In fluorene-9-carboxylic acid, C14H10O2, there are two crystallographically independent sets of molecules each of which exhibits hydrogen bonding of the cyclic dimer type about a center of symmetry. Additionally, one of the sets shows disordering of the carboxyl O atoms. Within the carboxyl groups, however, the carboxyl H atoms were found to be, or modelled as, ordered.