Matrix isolation, spectroscopic characterization, and photoisomerization of m-xylylene.

A new efficient synthesis of m-xylylene 1 is reported. The diradical 1 was trapped in argon matrices at 10 K and characterized by IR, UV-vis, and EPR spectroscopy. The syntheses reported before only allowed generation of 1 in organic glasses, and the spectroscopic identification was limited to fluorescence and EPR spectroscopy. Diradical 1 proved to be highly photolabile, and irradiation results in the formation of three isomeric hydrocarbons 7, 9, and 11 which could be identified by comparison of their IR spectra with the results of DFT calculations.