Insights into the effect of contact ion-pairs on C H bond activation for the synthesis of Ru(III)-NHC complexes: A combined experimental and computational study

The effect of contact ion pairs and comparison the three halide ions on electrophilic C-H activation during base-free synthesis Ru(III)-NHC complexes [RuIII(PyNHCR)(Cl)3(H2O)] (1a; R = Me, 1b; iPr) have been investigated. DFT modelling two pathways for formation complexes, viz. coordination pathway ion-pair pathway, reveals generation carbene. path is preferred azolium salts with Cl− I−, whereas Br−, reaction follows route leading to mixed complex. synthetic concerted-metalation-deprotonation (CMD) mechanism pair pathway. higher barrier can be explained in terms greater stabilization intermediates, compared transition states, due or hydrogen bonding ions. Furthermore, successful 1b from RuCl3·3H2O corresponding imidazolium salt precursor dioxane at 100°C validates conclusions studies.