ISOFULMINIC ACID - PHANTOM OR REALITY

The complex photochemistry of matrix-isolated dihaloformoximes 8a, 8b, and 8c, which are transformed upon irradiation into the new hydrogen- bonded complexes HalCN ... HOHal 10a-c', identified by their IR spectr a, has been unveiled. An earlier assignment of the experimental IR abs orptions to isofulminic acid HONC (4) must be withdrawn. A competitive reaction to the formation of complexes 10a-c' produces the hydrogen-b onded complexes HalNCO/HHal 12a-c', which can be regarded as intermedi ates on the photochemical pathway to the final product isocyanic acid HNCO (1), and are tentatively identified by their IR absorptions. Our findings are supported by deuteration experiments and theoretical calc ulations using the density functional method BLYP/6-311G.