o-Phenylene halocarbenonitrenes and o-phenylene chlorocarbenocarbene: a combined experimental and computational approach.

[reaction: see text] Computations find that o-phenylene(halo)carbenonitrenes 2-XN, X = F, Cl, Br, have quinoidal singlet biradical ground states such as the parent o-phenylenecarbenonitrene (2-HN). Compared to the parent 2-HN, halogen substitution stabilizes the A'' states relative to the A' ones. Halogen substitution also affects the barrier and exothermicity of the ring-opening reaction (to form unsaturated nitriles 4-XN, X = F, Cl, Br), but it has a smaller effect on the ring-closing reaction (to form benzo(aza)cyclobutadiene 3-XN, X = F, Cl, Br).

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.