Computational Details
Density functional theory (DFT) calculations were carried out using
Gaussian09 suite of programs [53-55]. Geometry optimization was
carried out using the density functional B3LYP and M06 methods and using
two different basis sets 6-31+G(d) and 6-311++G(d,p) [56]. The
results (relative energy values) obtained using M06/6-311++G(d,p) level
of quantum chemical methods are provided in Tables 1 and 2, the results
obtained using other three levels (as well as the corresponding absolute
energy values) are given in supporting information. All the minima are
characterized by zero negative frequencies and the transition states are
characterized by one negative frequency. The Gibb’s free energy values
are employed in the analysis. The bond dissociation energy values are
estimated by breaking the L-C bond in which the L is a fully
characterizable carbene unit.