Dimer-of-dimers model for the oxygen-evolving complex of photosystem II. Synthesis and properties of [MnIV4O5(terpy)4(H2O)2](ClO4)6

J Am Chem Soc. 2004 Jun 16;126(23):7345-9. doi: 10.1021/ja037389l.

Abstract

A dimer-of-dimers model compound for the oxygen-evolving complex of photosystem II, [[(H(2)O)(terpy)Mn(IV)(micro-O)(2)Mn(IV)(terpy)](2)(micro-O)](ClO(4))(6) (terpy = 2,2':6',2' '-terpyridine), has been prepared and characterized by X-ray crystallography and ESI-MS. Low pH was found to promote the disproportionation of [Mn(III/IV)(2)O(2)(terpy)(2)(OH(2))(2)](3+) to Mn(2+) and a Mn(IV/IV)(2)O(2)(terpy)(2) species; the latter complex slowly dimerizes to form the title complex. Protonation of a micro-oxo bridge is proposed to initiate the disproportionation, based on analogy with the [Mn(III/)(IV)(2)O(2)(bpy)(4)](3+) system.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Crystallography, X-Ray
  • Dimerization
  • Hydrogen-Ion Concentration
  • Models, Biological*
  • Molecular Structure
  • Organometallic Compounds / chemistry*
  • Organometallic Compounds / metabolism
  • Oxygen / metabolism*
  • Photosystem II Protein Complex / chemistry*
  • Photosystem II Protein Complex / metabolism*
  • Spectrometry, Mass, Electrospray Ionization
  • Spectrophotometry

Substances

  • (MnIV4O5(terpy)4(H2O)2)(ClO4)6
  • Organometallic Compounds
  • Photosystem II Protein Complex
  • Oxygen