Matrix-isolation and computational study of salicylhydroxamic acid and its photochemical degradation

The IR absorption spectrum of salicylhydroxamic acid (sha) isolated in an argon matrix at 12-21 K has been recorded. Calculations of all the possible entgegen and zusammen keto conformers of sha have been performed at the B3LYP/6-311++G(d,p) level of theory. The computed energies, optimized structures, and relative abundances show that sha exists in the matrix as the z,z,z,z-conformer [relative to the C-O(-H), C-C(-N), C-N and N-O bonds, respectively] and is stabilized by two intramolecular H-bonds. Photofragmentation of the compound in matrix and methanol-water solution has been obtained by irradiation with visible and ultraviolet light. o-Hydroxyphenylisocyanate is the main photolysis product in an argon matrix, while salicylamide is the primary photolysis product in methanol-water solution.