Experimental and Theoretical Studies of the Reactivity and Thermochemistry of Dicyanamide: N(CN)2–

Dicyanamide [N(CN)2–] is a common anionic component of ionic liquids, several of which have shown hypergolic reactivity upon mixing with white-fuming nitric acid. In this study, we explore the thermochemistry of dicyanamide and its reactivity with nitric acid and other molecules to gain insight into the initial stages of the hypergolic phenomenon. We have developed and utilized an electrospray ion source for our selected ion flow tube (SIFT) to generate the dicyanamide anion. We have explored the general reactivity of this ion with several neutral molecules and atoms. Dicyanamide does not show reactivity with O2, H2SO4, H2O2, DBr, HCl, NH3, N2O, SO2, COS, CO2, CH3OH, H2O, CH4, N2, CF4, or SF6 (k < 1 × 10–12 cm3/s); moreover, dicyanamide does not react with N atom, O atom, or electronically excited molecular oxygen (k < 5 × 10–12 cm3/s), and our previous studies showed no reactivity with H atom. However, at 0.45 Torr helium, we observe the adduct of dicyanamide with nitric acid with an effective bimolecula...