Crystal structure of 9-Oxofluorene-4-carboxylic acid

Abstract

The crystal structure of 9-oxofluorene-4-carboxylic acid has been determined by direct methods using three-dimensional X-ray diffraction data, and refined to R0·068 for 1323 'observed' reflections. Crystals are monoclinic, space group P2₁/c with 24 in a cell of dimensions a 3·843(3), b 7·986(5), c 3269(2) Å, β 96·64(4)º. The molecules form centrosymmetric hydrogen-bonded cyclic dimers [O···O 2·642(3) Å] with the plane of the carboxylic acid making an angle of 26·5º with that of the 9-oxofluorene group. Stacks of molecules form down the a axis with 3.843 Å. separation.