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organic compounds
The structures of two phases of fluorene-4-carboxylic acid, C14H10O2, from room-temperature growths have been determined. In the α phase, O—H
O hydrogen bonding occurs via cyclic dimers about a center of symmetry; in the β phase, cyclic dimers with O-HO hydrogen bonds are formed between two crystallographically inequivalent molecules and do not involve a center of symmetry, though centers of symmetry are present in the crystal. The present evidence strongly suggests that the β phase is metastable with respect to the α phase at room temperature, but the regions of stability have not been determined.
O hydrogen bonding occurs via cyclic dimers about a center of symmetry; in the β phase, cyclic dimers with O-HO hydrogen bonds are formed between two crystallographically inequivalent molecules and do not involve a center of symmetry, though centers of symmetry are present in the crystal. The present evidence strongly suggests that the β phase is metastable with respect to the α phase at room temperature, but the regions of stability have not been determined.
