Iron−Semiquinone, Semiquinone−Semiquinone, and Iron−Iron Magnetic Exchange in Monomeric and Dimeric Ferric Complexes Containing the 3,6-Di-tert-butyl-1,2-semiquinonate Ligand
- 1 January 1996
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 35 (4) , 1033-1038
- https://doi.org/10.1021/ic950595c
Abstract
Fe(3,6-DBSQ)(3) has been prepared by reacting 3,6-di-tert-butyl-1,2-benzoquinone with Fe(CO)(5). The complex has been characterized structurally [orthorhombic, Pbca, a = 18.277(5) Å, b = 11.634(3) Å, c = 39.903(10) Å, V = 8485(4) Å(3), Z = 8, R = 0.063], electrochemically, and magnetically. Ligand-based redox couples are observed in electrochemical experiments that consist of reversible or quasireversible Cat/SQ steps at negative potentials and irreversible SQ/BQ oxidations at positive potentials. Magnetic measurements show temperature dependence that arises from antiferromagnetic exchange. Data have been fit to an expression that includes the effects of both Fe-SQ and SQ-SQ exchange with the result that J(SQ-SQ) is larger in magnitude than J(Fe-SQ). In methanol, the complex undergoes solvolysis to form [Fe(3,6-DBSQ)(2)(&mgr;-OMe)](2). Structural characterization [triclinic, P&onemacr;, a = 11.441(2) Å, b = 11.514(2) Å, c = 14.552(2) Å, alpha = 67.86(1) degrees, beta = 70.51(1) degrees, gamma = 72.79(1) degrees, V = 1641.8(5) Å(3), Z = 1, R = 0.048] has shown that the molecule is a centrosymmetric dimer with no close intermolecular contacts. The temperature dependence of magnetic measurements has been fit to a model consisting of two interacting S = (3)/(2) centers that arise from strong Fe-SQ exchange with J(Fe-Fe) = -22.4 cm(-1).Keywords
This publication has 15 references indexed in Scilit:
- Potential for Redox Isomerism by Quinone Complexes of Iron(III). Studies on Complexes of the FeIII(N-N)(DBSQ)(DBCat) Series with 2,2'-Bipyridine and N,N,N',N'-Tetramethylethylenediamine ColigandsInorganic Chemistry, 1995
- Radical Superexchange in Semiquinone Complexes Containing Diamagnetic Metal Ions. 3,6-Di-tert-butyl-1,2-semiquinoate Complexes of Zinc(II), Cobalt(III), Gallium(III), and Aluminum(III)Inorganic Chemistry, 1994
- Valence localization in iron complexes with o-quinone-derived ligands studied by high magnetic field Moessbauer spectroscopyInorganic Chemistry, 1992
- Molecular topology exchange interaction: synthesis and magnetic properties of [Cu(II)3M(II)] (M = cadmium, nickel, manganese) tetranuclear speciesInorganic Chemistry, 1990
- Magnetic exchange interactions in semiquinone complexes of iron. Structural and magnetic properties of tris(3,5-di-tert-butylsemiquinonato)iron(III) and tetrakis(3,5-di-tert-butylsemiquinonato)tetrakis(3,5-di-tert-butylcatecholato)tetrairon(III)Journal of the American Chemical Society, 1989
- Exchange interaction in multinuclear transition-metal complexes. 6. Nature of metal-metal coupling in dinuclear iron(III) systems containing FeOFeO bridging unitsInorganic Chemistry, 1984
- Weak magnetic exchange interactions between paramagnetic metal ions and coordinated o-semiquinones in M(9,10-phenanthrenesemiquinone)2(pyridine)2 [M = nickel(II) and cobalt(II)] and tetranuclear M4(o-semiquinone)8 complexesInorganic Chemistry, 1981
- Exchange interactions in tris[cis-di-.mu.-hydroxo-bis(ethylenediamine)chromium(III)]chromium(III) tris(dithionate)octahydrateInorganic Chemistry, 1980
- Multistep redox series of the tris(o-semiquinone)chromium(III) complexesInorganic Chemistry, 1979
- Intramolecular antiferromagnetic exchange in tris(o-semiquinone) complexes of vanadium(III), chromium(III), and iron(III)Journal of the American Chemical Society, 1978