Theor. studies of the energetics of the imidazole mol. have established that it is 29 kcal mol-1 lower in energy than its NHC tautomer, which suggests that tautomoerization to NHC is thermodynamically unfavored. Following this, a theor. investigation carried out by Crabtree et al. on the thermodn. preference for N- vs. C- coordination in imidazoles went on to show that the opposite of this is obsd. when each is bound to a soft, late transition metal complex. It was therefore concluded through this study that while first row elements prefer binding via N, second and third row elem...