Photolysis of 3-(2-Formylphenyl)-3-chlorodiazirine in an Ar matrix at low temperature.

Photolysis of 3-(2-formylphenyl)-3-chlorodiazirine in an Ar matrix at 13 K was monitored by IR and UV-vis spectroscopies. Characterization of the products was carried out by comparing the spectra with the theoretical IR spectra obtained by using DFT, which suggested that anti,anti-2-formylphenyl(chloro)carbenes (a,a-2), ketenes (syn- and anti-3), chlorobenzocyclobutenone (4), and chloroisobenzofurane (5) were formed. This indicates that carbene 2 interacts with both hydrogen and oxygen in the formyl group. When the matrix containing a,a-2 was allowed to stand in the dark at 13 K, a gradual increase of the band due to anti-ketene 3 at the expense of 2 was observed. In contrast to its protio analogue, the deuterated carbene 2-d showed almost no changes either for the decay of 2-d or the growth of 3-d within the time range where the protio analogue appreciably decayed. These observations are interpreted in term of a quantum mechanical tunneling mechanism.