Ab initio study of C4H3 potential energy surface and reaction of ground-state carbon atom with propargyl radical
Article
Trung Ngoc, LE, Mebel, AM, Kaiser, RI. (2001). Ab initio study of C4H3 potential energy surface and reaction of ground-state carbon atom with propargyl radical
. JOURNAL OF COMPUTATIONAL CHEMISTRY, 22(13), 1522-1535. 10.1002/jcc.1105
Trung Ngoc, LE, Mebel, AM, Kaiser, RI. (2001). Ab initio study of C4H3 potential energy surface and reaction of ground-state carbon atom with propargyl radical
. JOURNAL OF COMPUTATIONAL CHEMISTRY, 22(13), 1522-1535. 10.1002/jcc.1105
The potential energy surface for the reaction of the ground-state carbon atom [C(3Pj)] with the propargyl radical [HCCCH2(X2B1)] is investigated using the G2M(RCC,MP2) method. Numerous local minima and transition states for various isomerization and dissociation pathways of doublet C4H3 are studied. The results show that C(3Pj) attacks the π system of the propargyl radical at the acetylenic carbon atom and yields the n-C4H3(2A′) isomer i3 after an 1,2-H atom shift. This intermediate either splits a hydrogen atom and produces singlet diacetylene, [HCCCCH (p1) + H] or undergoes (to a minor amount) a 1,2-H migration to i-C4H3(2A′) i5, which in turn dissociates to p1 plus an H atom. Alternatively, atomic carbon adds to the triple C≡C bond of the propargyl radical to form a three-member ring C4H3 isomer i1, which ring opens to i3. Diacetylene is concluded to be a nearly exclusive product of the C(3Pj) + HCCCH2 reaction. At the internal energy of 10.0 kcal/mol above the reactant level, Rice-Ramsperger-Kassel-Marcus calculations show about 91.7% of HCCCCH comes from fragmentation of i3 and 8.3% from i5. The other possible minor channels are identified as HCCCC + H2 and C2H + HCCH.
