TY - JOUR
T1 - Mechanisms of the reactions of W and W+ with NOx (x = 1, 2)
T2 - A computational study
AU - Chen, Hsin Tsung
AU - Musaev, Djamaladdin G.
AU - Irle, Stephan
AU - Lin, Ming-Chang
PY - 2007/2/8
Y1 - 2007/2/8
N2 - The mechanisms of the reactions of W and W+ with NOx (x = 1, 2) were studied at the CCSD(T)/[SDD+6-311G(d)]//B3LYP/[SDD+6-31G(d)] level of theory. It was shown that the insertion pathway of the reaction W( 7S) + NO2(2A1) is a multistate process, which involves several lower lying electronic states of numerous intermediates and transition states, and leads to oxidation, WO( 3Σ) + NO(2Π), and/or nitration, WN( 4Σ) + O2(3Σg -), of the W-center. Oxidation products WO(3Σ) + NO(2Π) lie 87.6 kcal/mol below the reactants, while the nitration channel is only 31.0 kcal/mol exothermic. Furthermore, it was shown that nitration of W with NO2 is kinetically less favorable than its oxidation. The addition-dissociation pathway of the reaction W(7S) + NO2(2A1) proceeds via the octet (ground) state potential energy surface of the reaction, requires 3.3 kcal/mol barrier, and leads exclusively to oxidation products. Calculations show that oxidation of the W+ cation by NO2 is a barrierless process in the gas phase, proceeds exclusively via the insertion pathway, and is exothermic by 82.9 kcal/mol. The nitration of W+ by NO2 is only 14.1 kcal/mol exothermic and could be accessible only under high-temperature conditions. Reactions of M = W/W+ with NO are also barrierless processes in the gas phase and lead to the N-O insertion product NMO, which are 105.4 and 77.4 kcal/mol lower than the reactants for W and W+, respectively.
AB - The mechanisms of the reactions of W and W+ with NOx (x = 1, 2) were studied at the CCSD(T)/[SDD+6-311G(d)]//B3LYP/[SDD+6-31G(d)] level of theory. It was shown that the insertion pathway of the reaction W( 7S) + NO2(2A1) is a multistate process, which involves several lower lying electronic states of numerous intermediates and transition states, and leads to oxidation, WO( 3Σ) + NO(2Π), and/or nitration, WN( 4Σ) + O2(3Σg -), of the W-center. Oxidation products WO(3Σ) + NO(2Π) lie 87.6 kcal/mol below the reactants, while the nitration channel is only 31.0 kcal/mol exothermic. Furthermore, it was shown that nitration of W with NO2 is kinetically less favorable than its oxidation. The addition-dissociation pathway of the reaction W(7S) + NO2(2A1) proceeds via the octet (ground) state potential energy surface of the reaction, requires 3.3 kcal/mol barrier, and leads exclusively to oxidation products. Calculations show that oxidation of the W+ cation by NO2 is a barrierless process in the gas phase, proceeds exclusively via the insertion pathway, and is exothermic by 82.9 kcal/mol. The nitration of W+ by NO2 is only 14.1 kcal/mol exothermic and could be accessible only under high-temperature conditions. Reactions of M = W/W+ with NO are also barrierless processes in the gas phase and lead to the N-O insertion product NMO, which are 105.4 and 77.4 kcal/mol lower than the reactants for W and W+, respectively.
UR - http://www.scopus.com/inward/record.url?scp=33847055489&partnerID=8YFLogxK
U2 - 10.1021/jp067238f
DO - 10.1021/jp067238f
M3 - Article
C2 - 17266241
AN - SCOPUS:33847055489
SN - 1089-5639
VL - 111
SP - 982
EP - 991
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 5
ER -