Agreement between experiment and hybrid DFT calculations for O-H bond dissociation enthalpies in manganese complexes
2005 (English)In: Journal of Computational Chemistry, ISSN 0192-8651, E-ISSN 1096-987X, Vol. 26, no 7, 661-667 p.Article in journal (Refereed) Published
Information on the accuracy of DFT functionals for redox reactions in transition metal systems is rather limited. To analyze the performance of some popular functionals for redox reactions in manganese systems, calculated O-H bond dissociation enthalpies for Mn-ligands in six different complexes are compared to experimental results. In this benchmark, B3LYP performs well with a mean absolute error of 3.0 kcal/mol. B98 gives similar results to B3LYP (error of 3.8 kcal/mol). B3LYP* gives lower O-H bond strengths than B3LYP and has a mean error of 5.0 kcal/tnol. Compared to B98 and B3LYP, B3LYP* has an error trend for the manganese ligands that is more similar to the error for a free water molecule. The nonhybrid functional BLYP consistently and significantly underestimates the O-H bond strengths by approximately 20 kcal/mol. HCTH407 has a rather large mean error of 9.4 kcal/mol and shows no consistent trend. The results support the use of hybrid functionals and the present computational method for large model systems containing manganese. An example is the oxygen evolving complex in photosystem 11 where hybrid functionals predict the appearance of a Mn(IV)-oxyl radical before the O-O bond formation step.
Place, publisher, year, edition, pages
2005. Vol. 26, no 7, 661-667 p.
density functional theory, transition metal complexes, bond dissociation enthalpies, photosynthesis, mechanism
IdentifiersURN: urn:nbn:se:uu:diva-145471DOI: 10.1002/jcc.20206OAI: oai:DiVA.org:uu-145471DiVA: diva2:396512