Initial Thermal Decomposition Mechanism of (NH₂)₂C=C(NO₂)(ONO) Revealed by Double-Hybrid Density Functional Calculations.

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.

SUBMITTER: Guan Y 

PROVIDER: S-EPMC8210442 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature