Abstract: | o‐Benzenedicarbaldehyde (systematic name: benzene‐1,2‐dicarbaldehyde), C8H6O2, exhibits a weak intramolecular hydrogen bond between an aldehyde H atom and the O atom of the adjacent aldehyde group, with a C?O distance of 2.852 (2) Å. m‐Benzenedicarbaldehyde (systematic name: benzene‐1,3‐dicarbaldehyde), C8H6O2, occurs as two different isomorphs. In all three crystals, there are intermolecular C—H?O contacts involving both aldehyde and ring H atoms. |