title: An ab initio and DFT study of radical addition reactions of imidoyl and thioyl radicals to methanimine.
abstract: Ab initio and DFT calculations reveal that both imidoyl and thioyl radicals add to the nitrogen end of methanimine through simultaneous SOMO-π*(imine), SOMO-π(imine), SOMO-LP(N) and π*(radical)-LP(N) interactions between the radical and the imine. At the CCSD(T)/cc-pVDZ//BHandHLYP/cc-pVTZ level of theory, barriers of 13.8 and 26.1 kJ mol(-1) are calculated for the attack of the methylimidoyl radical at the carbon- and nitrogen- end of methanimine, respectively, indicating that the imidoyl radial has a preference for addition to the nitrogen end of imine. On the other hand, barriers of 25.1 and 13.4 kJ mol(-1) are calculated at the same level of theory for the addition reaction of the methanethioyl radical at the carbon- and nitrogen- end of methanimine, respectively. Natural bond orbital (NBO) analysis at the BHandHLYP/6-311G** level of theory reveals that SOMO-π*(imine), SOMO-π(imine), SOMO-LP(N) and π*(radical)-LP(N) interactions are worth 111, 89, 115 and 17 kJ mol(-1), respectively, in the transition state (4) for the reaction of methylimidoyl radical at the nitrogen end of methanimine; similar interactions are observed for the chemistry involving all the radicals studied here. These multi-component interactions are responsible for the unusual motion vectors associated with the transition states involved in these reactions.
authors.affiliation: School of Chemistry, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Sara H
authors.initials: SH
authors.lastname: Kyne
authors.forename: Carl H
authors.initials: CH
authors.lastname: Schiesser
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsubara
mesh_terms: D005583:Fourier Analysis; D005609:Free Radicals / Q000737:chemistry; D007097:Imines / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D013457:Sulfur Compounds / Q000737:chemistry*
chemical_list: D005609:Free Radicals; D007097:Imines; D013457:Sulfur Compounds; C024664:methyleneimine