The UV photolysis of [2.2] metaparacyclophanediones 4b and 4c leads to α-cleavage and formation of CO, p-xylylene 5, and m-benzynes 2b and c with a fluorine or methyl substituent in the 5-position, respectively. The IR spectra of 2b and 2c were assigned by comparison with that of the parent m-benzyne 2a and with spectra calculated at the BLYP/6-311G (d, p) level of theory. Both band positions and intensities of the experimental spectra are in ...
