Carbones and Heavier Ylidones (EL2) in Frustrated Lewis Pair Chemistry: Influence of the Nature of EL2 on Dihydrogen Activation

The role of carbones (CL2; L = phosphines vs carbenes) as Lewis bases in dihydrogen (H2) activation reactions in the presence of the Lewis acid B­(C6F5)3 has been computationally explored by means of density functional theory calculations. To this end, the interaction between H2 and the [carbone···B­(C6F5)3] pair along the reaction coordinate has been quantitatively analyzed in detail and compared to the parent [tBu3P···B­(C6F5)3] frustrated Lewis pair. In addition, the influence on the reactivity of both the nature of the central E atom and the surrounding ligands in ylidones (EL2) has also been considered. It is found that the activation barrier of the H2 activation reaction as well as the geometry of the corresponding transition states strongly depends on the nature of both E and L in the sense that lower barriers are systematically associated with earlier transition states. Our calculations identify heavier EL2 as the most active systems to achieve facile H2 activation reactions.