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Symmetry and Steric Effects on Spin States in Transition Metal Complexes

  1. Ryan M. Meier,
  2. Timothy P. Hanusa

Published Online: 15 JUN 2011

DOI: 10.1002/0470862106.ia478

Encyclopedia of Inorganic Chemistry

Encyclopedia of Inorganic Chemistry

How to Cite

Meier, R. M. and Hanusa, T. P. 2011. Symmetry and Steric Effects on Spin States in Transition Metal Complexes. Encyclopedia of Inorganic Chemistry. .

Author Information

  1. Vanderbilt University, Nashville, TN, USA

Publication History

  1. Published Online: 15 JUN 2011

Abstract

Changes in the magnetic characteristics of transition metal complexes, particularly, their metal spin states, are most commonly achieved by varying the electron donor/acceptor properties of coordinated ligands. In some systems, it is possible to increase the steric bulk of ligands so that intramolecular crowding leads to changes in metal-ligand bond distances; longer bonds produce weaker ligand fields and stabilize high-spin or spin-crossover complexes. Steric effects are also often associated, albeit indirectly, with a mechanism for influencing spin states that relies on modifying the symmetry-based interactions of metal and ligand orbitals. Particular ligand orientations, as in bis(indenyl) compounds [M(R9C7)2], can be changed as the result of interligand steric pressure or crystal packing effects; such differences can alter metal d-orbital energy levels and hence the stability of spin states. Both steric and symmetry effects add to the repertoire of techniques that can be used to control magnetic properties in transition metal complexes.

Keywords:

  • spin state;
  • steric bulk;
  • symmetry;
  • solid state structures;
  • transition metal