AB-INITIO STUDY OF THE DISSOCIATION OF FORMYL CYANIDE

[[abstract]]The energetics of the unimolecular dissociation of formyl cyanide, HCOCN, along three paths were examined by ab initio computations. The energy barriers for unimolecular dissociation, calculated at the QCISD(T)/6-311(3d, 3p)//QCISD/6-311(d, p) level of theory with correction for zero-point energy, are 64.04 and 62.17 kcal/mol for paths 1 and 2. The barriers for two successive steps of path 3, involving an intermediate, HCONC, which lies 13.06 kcal/mol above formyl cyanide, are 42.74 and 50.48 kcal/mol for the first and second steps. The rates of reaction along paths 1, 2 and 3 are 3.60 X 10(-34), 7.61 X 10(-33) and 1.59 X 10(-33) s(-1) at 300 K, and 7.11 X 10(-7), 2.48 X 10(-6) and 2.20 X 10(-6) s(-1) at 700 K, respectively. At room temperature formyl cyanide does not decompose via unimolecular decomposition because the rate constants of all three paths are minute.[[fileno]]2010305010019[[department]]化學