Characterization of synthetic oxomanganese complexes and the inorganic core of the O2-evolving complex in photosystem II: Evaluation of the DFT/B3LYP level of theory

Eduardo M. Sproviero, Jose A. Gascon, James P. McEvoy, Gary W. Brudvig, Victor S. Batista

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87 Citations (Scopus)

Abstract

The capabilities and limitations of the Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional are investigated as applied to studies of mixed-valent multinuclear oxomanganese complexes. Benchmark calculations involve the analysis of structural, electronic and magnetic properties of di-, tri- and tetra-nuclear Mn complexes, previously characterized both chemically and spectroscopically, including the di-μ-oxo bridged dimers [MnIIIMnIV(μ-O)2(H2O)2(terpy)2]3+ (terpy = 2,2′:6,2″-terpyridine) and [MnIIIMnIV(μ-O)2(phen)4]3+ (phen = 1,10-phenanthroline), the Mn trimer [Mn3O4(bpy)4(H2O)2]4+ (bpy = 2,2′-bipyridine), and the tetramer [Mn4O4L6]+ with L = Ph2 PO2-. Furthermore, the density functional theory (DFT) B3LYP level is applied to analyze the hydrated Mn3O4CaMn cluster completely ligated by water, OH-, Cl-, carboxylate and imidazole ligands, analogous to the '3+1 Mn tetramer' of the oxygen-evolving complex of photosystem II. It is found that DFT/B3LYP predicts structural and electronic properties of oxomanganese complexes in pre-selected spin-electronic states in very good agreement with X-ray and magnetic experimental data, even when applied in conjunction with rather modest basis sets. However, it is conjectured that the energetics of low-lying spin-states is beyond the capabilities of the DFT/B3LYP level, constituting a limitation to mechanistic studies of multinuclear oxomanganese complexes where until now the performance of DFT/B3LYP has raised little concern.

Original languageEnglish
Pages (from-to)786-800
Number of pages15
JournalJournal of Inorganic Biochemistry
Volume100
Issue number4
DOIs
Publication statusPublished - Apr 1 2006

Keywords

  • DFT/B3LYP
  • Exchange coupling
  • O-evolving complex
  • Oxomanganese complex
  • Photosystem II

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry

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