The catalysis of C-O bond activation of the lignin beta-O-4 model compound, 2-phenoloxy-1-phenolethanol, was investigated using group 8 (Fe, Ru and Os) pincer complexes. Reaction mechanisms and thermodynamics for the catalysis were studied using B3LYP/CEP-31G. Solvent effects were considered using a SMD solvation model for 1,4-dioxane. The considered pincer complexes include combinations of the three metals with five different pincer ligands (PNP, NNN, PCP, PCN and NCN). All possible multiplicities and conformations were taken into account. The reaction energetics of all metalligand combinations were compared and the thermodynamic nature of transition metal activation of the beta-O-4 bond was discovered. The studies suggest that C-O bond activation by transition metal catalysts is essentially controlled by the ability of the metal center to donate electrons to the C-O bond; ligands that donate electrons to the metal center tend to facilitate the cleavage of the C-O bond. (c) 2015 Elsevier B.V. All rights reserved.