8. Reversible Spin Pairing in Crystalline Organic Radicals

  1. MALCOLM A. HALCROW
  1. Jeremy M. Rawson and
  2. John J. Hayward

Published Online: 18 JAN 2013

DOI: 10.1002/9781118519301.ch8

Spin-Crossover Materials: Properties and Applications

Spin-Crossover Materials: Properties and Applications

How to Cite

Rawson, J. M. and Hayward, J. J. (2013) Reversible Spin Pairing in Crystalline Organic Radicals, in Spin-Crossover Materials: Properties and Applications (ed M. A. HALCROW), John Wiley & Sons Ltd, Oxford, UK. doi: 10.1002/9781118519301.ch8

Editor Information

  1. School of Chemistry, University of Leeds, UK

Author Information

  1. Department of Chemistry and Biochemistry, The University of Windsor, Canada

Publication History

  1. Published Online: 18 JAN 2013
  2. Published Print: 15 FEB 2013

ISBN Information

Print ISBN: 9781119998679

Online ISBN: 9781118519301

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Keywords:

  • dimerisation;
  • electronic structures;
  • free-radicals;
  • organic spin-transition materials;
  • pairing energy;
  • reversible spin pairing;
  • trithiatriazinyl (TTTA)

Summary

This chapter considers organic spin-transition materials whose electronic structures can be manipulated in a conceptually similar but substantially different chemical fashion, by examining the fine interplay between inter-electron repulsion or pairing energy and promotion energy to a low-lying vacant orbital. It begins with a discussion of stable free-radicals and their tendency to associate to form dimmers. The chapter focuses on computational and experimental studies of the electronic structures of these dimers in the gas phase and in solution. It chapter extends these discussions to the solid state and investigates examples to explain (i) thermal population of electronic excited states leading to a gradual thermal evolution of paramagnetism upon warming, and (ii) first order solid state phase transitions in which bond cleavage can lead to abrupt diamagnetic-paramagnetic phase transitions. It presents a case study on trithiatriazinyl (TTTA), which is the most comprehensively studied member of the family of spin-transition compounds.