MATRIX-ISOLATED BINARY AND TERNARY COMPLEXES FORMED IN PHOTOCHEMICAL DECOMPOSITION OF FORMIC-ACID ANHYDRIDE

Primary dissociation pathways of formic acid anhydride have been investigated in low-temperature argon matrices. Strong indications were found for the photodecomposition product dependence upon the conformation of the precursor: the most stable conformer yields complexes between formic acid and carbon monoxide, whereas the higher energy species yield ternary complexes composed of the primary monomers, H-2, CO, CO2, and H2O. Infrared spectra and vibrational assignments for the complexes are given. The OH torsional and stretching modes of formic acid are substantially perturbed upon complexation. Also, the asymmetric stretching mode of H2O in the ternary complex H2O + 2CO is markedly coupled to the librational motion of CO in solid argon. The possibility of trapping cis-formic acid trapped as a decomposition product is discussed.