Vibrational Excitation in the Products of S-Tetrazine Photolysis

Abstract

Gaseous s-tetrazine absorbs visible light and decomposes with almost unit quantum yield [1–5] to form stable products. We estimate the heat of formation

$$ s - {C_2}{H_2}{N_4} + hv \to {N_2} + 2HCN $$

((1))

of s-tetrazine to be 113 kcal/mole from comparison with other azabenzene [6]; the heat of reaction (1) including the energy of a photon at 500 nm is then ΔH = -108 kcal/mole. Though this exothermicity is not enough to produce electronically excited products, HOCHSTRASSER and KING [4] have suggested that the N₂ and HCN might be formed in vibrationally excited states.