[3 + 2] Versus [2 + 2] addition: A density functional theory study on the mechanistic aspects of transition-metal-assisted formation of 1,2-dinitrosoalkanes

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Hindawi Publishing Corporation
The pathways for the transition metal-assisted formation of 1,2-dinitrosoalkane complexes of cobalt and its congeners, have beenstudied using DFT/M06 with the LACVP∗basis set. The activation barriers for the one-step [3 + 2] addition pathway for theformation of 1,2-dinitrosoalkanes, proposed by Bergman and Becker, are generally low compared to the activation barriers for the[2 + 2] addition to form an intermediate, which is the first of the two-step pathway proposed by Rapp ́e and Upton, which are veryhigh. The barriers of the rearrangement of the Rapp ́e intermediates to the final products by reductive elimination involving thesecond metal-nitrogen𝜋-bond are also very high. The reactions of the Co complexes have lower activation barriers than Rh andIr complexes. The barriers of the reactions involving olefins with electron-donating groups are generally lower compared to thereactions of the parent (unsubstituted) ethylene while the activation barriers for reactions of olefins with electron-withdrawinggroups are generally higher compared to the parent (unsubstituted) ethylene. The one-step [3 + 2] pathway remains the mostfavoured irrespective of the metal centre or the nature of the olefin. The mechanism of the reaction is therefore settled in favour ofthe [3 + 2] addition pathway.
An article published by Hindawi Publishing Corporation and also available at http://dx.doi.org/10.1155/2016/4538696
Hindawi Publishing CorporationJournal of ChemistryVolume 2016, Article ID 4538696, 10 pageshttp://dx.doi.org/10.1155/2016/4538696