Ligand Design for Securing Ferromagnetic Exchange Coupling in Multimetallic Complexes

Scott W. Gordon‐Wylie, Emile L. Bominaar, Terrence J. Collins, José M. Workman, Brian L. Claus, Robert E. Patterson, Stacy A. Williams, Brenda J. Conklin, Gordon T. Yee, Susan E Weintraub

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19 Scopus citations


An approach is suggested for using ligands to control exchange coupling in multinuclear ions. The idea arose from structural, EPR, and magnetic studies of [PPh4]3 (Scheme 1). Ferromagnetic coupling has been found between the CoII and each CoIII in 3 with J = −22 ± 5 cm−1 (JS1 · S2). It is suggested that dominant antiferromagnetic superexchange is absent because of the strong σ‐donor capacity of the tetradentate ligand [k4‐PAC*]4− (Fig. 1). The ligand interacts at CoIII primarily with a single d orbital; it is thus best able to participate in superexchange. The interaction makes the unique d orbital strongly σ‐antibonding and empty for each d6, S = 1, CoIII ion in 3, that is, unavailable for antiferromagnetic coupling, but available for ferromagnetic pathways by a Goodenough‐Kanamori mechanism. By corollary, when any [k4‐PAC*]4−‐type ligand with any magnetic ion Ma in the tetradentate site binds any magnetic ion Mb in the bidentate site, ferromagnetic coupling should be favored provided Ma is not a d9 ion.

Original languageEnglish (US)
Pages (from-to)528-537
Number of pages10
JournalChemistry - A European Journal
Issue number8
StatePublished - 1995


  • exchange coupling
  • ferromagnetic properties
  • ligand design
  • magnetic properties
  • multimetallic complexes

ASJC Scopus subject areas

  • Chemistry(all)


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