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Electron Transfer in Coordination Compounds

  1. John F. Endicott

Published Online: 15 DEC 2011

DOI: 10.1002/9781119951438.eibc0064

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Endicott, J. F. 2011. Electron Transfer in Coordination Compounds. Encyclopedia of Inorganic and Bioinorganic Chemistry. .

Author Information

  1. Wayne State University, Detroit, MI, USA

Publication History

  1. Published Online: 15 DEC 2011

Abstract

The transfer of an electron between a transition metal donor and a transition metal acceptor can be promoted by the absorption of either thermal or light energy. The thermal processes have been experimentally determined to span a range of about 1020 in their ambient rates of electron transfer. The same molecular properties that determine the electron-transfer reactivity also determine the correlated electron-transfer absorption or emission band energy, band shape, and absorptivity. The relationships between the thermal-kinetic and the spectroscopic observations are relatively simple when there is very little electron delocalization between the donor and acceptor, the weak-coupling limit. This limit applies to most bimolecular electron-transfer reactions of transition metals and to the spectroscopy of transition metal ion pairs; this is the limit treated well by Marcus theory. When the donor and acceptor are covalently linked, interactions of the donor and acceptor with the linker often increase the coupling in such a way as to enhance the reactivity and to alter the spectroscopy. Most of these linker-induced changes of reactivity and spectroscopy can be treated in terms of perturbation theory-based alterations of the behavior in the weak-coupling limit. Reactivity in some very strongly coupled complexes seems to fall outside the standard theoretical framework; many such systems seem to implicate nuclear motions of the linker in facilitating the donor–acceptor electronic coupling. Extensions to biological, multicentered, and heterogeneous systems containing transition metal complexes are briefly considered.

Keywords:

  • acceptor;
  • adiabatic;
  • charge transfer;
  • diabatic;
  • donor;
  • electronic coupling;
  • electron transfer;
  • electronic coupling;
  • Franck–Condon factor;
  • Franck–Condon parameters;
  • ion-pair charge transfer;
  • nonadiabatic;
  • nuclear tunneling;
  • reorganizational energy;
  • vibronic coupling