Magnetic Susceptibility, EPR, Mössbauer, and X-ray Investigations of Heteropolynuclear Clusters Containing Iron(III) and Copper(II) Ions: {Cu(Mesalen)}2Fe(acac)(NO3)2 and {Cu(Mesalen)}3Fe(acac)(PF6)2

Irène Morgenstern-Badarau*, Daniel Laroque, Eckhard Bill, Heiner Winkler, Alfred X. Trautwein, Francis Robert, Yves Jeannin

*Corresponding author for this work
13 Citations (Scopus)

Abstract

Magnetic susceptibility, EPR, Mössbauer, and X-ray studies have been performed on heteropolynuclear clusters containing iron(III) and copper(II) ions: {Cu(Mesalen)}2Fe(acac)(NO3)2 and |Cu(Mesalen))3Fe(acac)(PF6)2 (Mesalen = l,2-bis((methyl-salicylidene)amino)ethane; acac = acetylacetonato(l-)). The spectroscopic results obtained for the trinuclear system {2CuFe} suggest strong antiferromagnetic coupling of iron(III) to the two copper(II) ions to yield a S = 3/2 ground-state system. X-ray studies reveal that the tetranuclear system {3CuFe} crystallizes in the hexagonal space group P6122 with Z = 6, a = b = 14.471 (3) Å, and c = 50.372 (2) Å; it consists of a trinuclear unit {2CuFe} plus a mononuclear Cu(Mesalen) molecule, arranged in helicoidal polymeric chains. Magnetic susceptibility, EPR, and Mössbauer studies under moderate fields consistently show that the {2CuFe} and Cu(Mesalen) moieties are weakly interacting. Under high-fíeld and low-temperature conditions, this interaction is not observable in Mössbauer spectroscopy. Since the Mössbauer spectra under these conditions are identical for the tri- and tetranuclear clusters, we conclude that the {2CuFe} moieties are very similar in both cluster types. The presence of the additional Cu(Mesalen) molecule in the tetranuclear cluster expresses itself in the Mössbauer spectra only at elevated temperatures by an enhancement of the spin-spin relaxation rates of nearly 1 order of magnitude larger compared to the trinuclear cluster.

Original languageEnglish
JournalInorganic Chemistry
Volume30
Issue number16
Pages (from-to)3180-3188
Number of pages9
ISSN0020-1669
DOIs
Publication statusPublished - 01.08.1991

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