Initial Thermal Decomposition Mechanism of (NH2)2C=C(NO2)(ONO) Revealed by Double-Hybrid Density Functional
Yulei Guan1, Xingzhen Zhu1, Yanyan Gao1
1School of Chemical Engineering/Xi'an Key Laboratory of Special Energy Materials, Northwest University, Xi'an 710069, China.
Abstract:
This work employs double-hybrid density functionals to re-examine the CO-NO bond dissociation mechanism of nitrite isomer of 1,1-diamino-2,2-dinitro-ethylene (DADNE) into (NH2)2C=C(NO2)O and nitric monoxide (NO). The calculated results confirm that an activated barrier is present in the CO-NO bond dissociation process of (NH2)2C=C(NO2)(ONO). Furthermore, it is proposed that a radical-radical adduct is involved in the exit dissociation path with subsequent dissociation to separate (NH2)2C=C(NO2)O and NO radicals. The activation and reaction enthalpies at 298.15 K for the nitrite isomer dissociation are predicted to be 43.6 and 5.4 kJ mol-1 at the B2PLYP/6-31G(d,p) level, respectively. Employing the B2PLYP/6-31G(d,p) reaction energetics, gradient, Hessian, and geometries, the kinetic model for the CO-NO bond dissociation of (NH2)2C=C(NO2)(ONO) is obtained by a fitting to the modified Arrhenius form 1.05 × 1013(T/300)0.39 exp[-27.80(T + 205.32)/R(T 2 + 205.322)] in units of per second over the temperature range 200-3000 K based on the canonical variational transition-state theory with multidimensional small-curvature tunneling.
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