Mechanism of the thermal decomposition and the (n-{pi}*) excited states of azomethane
- Univ. of Georgia, Athens, GA (United States)
The mechanism of azomethane decomposition CH{sub 3}N=NCH{sub 3} {yields} 2CH{sub 3}{sup {center_dot}} + N{sub 2} has been investigated with ab initio quantum mechanical approaches. The methods include self-consistent field (SCF), two-reference SCF (TCSCF), single- and double-excitation configuration interaction (CISD), two-reference CISD with TCSCF optimized molecular orbitals (TCSCF-CISD), single- and double-excitation coupled cluster (CCSD), and the single-, double-, and perturbative triple-excitation coupled cluster [CCSD(T)]. The `synchronous` decomposition pathway, in which a transition state of two equal distance C-N bonds is involved, was shown to be infeasible. Both cis- and trans-azomethane break one C-N bond at the first step and form the CH{sub 3} and CH{sub 3}N{sub 2} radicals; then the methyldiazenyl radical further decomposes into CH{sub 3} and N{sub 2}. The first C-N bond of cis- and trans-azomethane breaks without a transition state, with the predicted D{sub 0} of 46.3 kcal/mol for trans-azomethane at the TZ2P CCSD(T) level. CH{sub 3}N{sub 2} decomposes through a barrier of nearly 2.3 kcal/mol into CH{sub 3} and N{sub 2}, as reported by the authors previously. cis-Azomethane was predicted to be about 9.1 kcal/mol higher in energy than trans-azomethane [TZ2P CCSD(T)]. 45 refs., 1 fig., 11 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG05-94ER14428
- OSTI ID:
- 50783
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 19 Vol. 99; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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