Theoretical study on the reactions of the cyclic trinitrogen radical toward oxygen and water.

Recently, the detection of the neutral simplest all-nitrogen ring, cyclic-N(3) radical, has been realized via various techniques, which has led to numerous studies on its structures, energetics, and spectroscopy. In particular, it has been postulated as a possible building block of high energy density materials. Yet, its intermolecular reactivity is poorly understood. In this paper, we for the first time studied the reactions of cyclic-N(3) with the widespread oxygen and water at the CCSD(T)/aug-cc-pVTZ //B3LYP/6-311++G(d,p)+ZPVE and G3B3//B3LYP/6-311++G(d,p) (italics) levels. An addition-elimination mechanism was revealed for the cyclic-N(3) + O(2) reaction that results in the elementary product N(2) + NO + (3)O with an overall barrier as high as 11.8 (11.0) kcal/mol. The calculated low rate constants (even at high temperatures) show that the cyclic-N(3) radical is stable against oxygen. The cyclic-N(3) + H(2)O reaction is associated with a quasi H-abstraction mechanism forming the product cyclic-N(3)H + OH with the rather high barrier of 35.7 (36.2) kcal/mol. This indicates that cyclic-N(3) is chemically inert toward H(2)O. Chemical implications of the present work are discussed.