Stepwise substituting magnetic centres in a giant cluster host system

Achim Müller*, Winfried Plass, Erich Krickemeyer, Roberta Sessoli, Dante Gatteschi, Jochen Meyer, Hartmut Bögge, Monika Kröckel, Alfred X. Trautwein

*Corresponding author for this work
25 Citations (Scopus)

Abstract

In the polyoxomolybdate shell of the cluster compound (NH4)21[{VIVO(H2O)} 6{Mo(μ-H2O)2(μ-OH)Mo}3{Mo 15(MoNO)2-O58(H2O)2} 3] ([V6]), {FeIII(H2O)2} and {FeII(H2O)2} moieties can be incorporated at the positions of the {VO(H2O)} groups. On adding FeCl3·6H2O in excess to a solution from which pure [V6] can be isolated, the cluster compound (NH4)15[{FeIII(H2O) 2}6{Mo(μ-H2O)2-(μ-OH)Mo} 3{MO15(MoNO)2O58(H 2O)2}3] ([Fe6]) is formed. By adding varying amounts of FeCl2·4H2O or FeCl3·6H2O to such a solution, a series of compounds can be isolated with different ratios of oxovanadium(IV), iron(III), and iron(II) centres. The experimental conditions allow tuning of these ratios in the prepared compounds, 〈V4Fe2〉, 〈V3Fe3〉, 〈V2Fe4〉 and 〈VFe5〉 with varying iron(III) / iron(II) ratio (depending on the degree of oxidation of iron(II) centres) and 〈VFeIII 5〉. These formulae correspond to those of [V6] and [Fe6] with the relevant intermediate NH4 + content. The synthesized compounds were characterized by elemental analyses, different spectroscopic methods, and X-ray crystal structure analyses as well as 57Fe-Mößbauer spectroscopy which allowed determination of the iron(III) / iron(II) ratio. The magnetic properties of all cluster compounds were carefully investigated. For one of the mixed systems an interesting ferrimagnetic behaviour is observed and can only be explained if the different magnetic centres occur within a single cluster shell and are not separated in different clusters.

Original languageEnglish
JournalInorganica Chimica Acta
Volume271
Issue number1-2
Pages (from-to)9-12
Number of pages4
ISSN0020-1693
DOIs
Publication statusPublished - 15.04.1998

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