Premium
Ligand Design for Securing Ferromagnetic Exchange Coupling in Multimetallic Complexes
Author(s) -
GordonWylie Scott W.,
Bominaar Emile L.,
Collins Terrence J.,
Workman José M.,
Claus Brian L.,
Patterson Robert E.,
Williams Stacy A.,
Conklin Brenda J.,
Yee Gordon T.,
Weintraub Susan T.
Publication year - 1995
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19950010806
Subject(s) - ferromagnetism , coupling (piping) , ligand (biochemistry) , business , materials science , chemistry , condensed matter physics , physics , metallurgy , receptor , biochemistry
Abstract An approach is suggested for using ligands to control exchange coupling in multinuclear ions. The idea arose from structural, EPR, and magnetic studies of [PPh 4 ]3 (Scheme 1). Ferromagnetic coupling has been found between the Co II and each Co III in 3 with J = −22 ± 5 cm −1 ( JS 1 · S 2 ). It is suggested that dominant antiferromagnetic superexchange is absent because of the strong σ‐donor capacity of the tetradentate ligand [k 4 ‐PAC * ] 4− (Fig. 1). The ligand interacts at Co III 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 d 6 , S = 1, Co III ion in 3, that is, unavailable for antiferromagnetic coupling, but available for ferromagnetic pathways by a Goodenough‐Kanamori mechanism. By corollary, when any [k 4 ‐PAC * ] 4− ‐type ligand with any magnetic ion M a in the tetradentate site binds any magnetic ion M b in the bidentate site, ferromagnetic coupling should be favored provided M a is not a d 9 ion.