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Issue 24, 2002
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New pentanuclear mixed valence Co(II)–Co(III) complexes of “short” salen homologues

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Abstract

We describe herein a series of novel pentanuclear Co(II)–Co(III) mixed-valence cationic complexes of formula [Co5L43-OH)2]+ {L2− = 2,2′-[1,1-methanediylbis(nitrilomethylidene)diphenate] or its arylmethane analogues}, obtained by controlled oxidation of [Co2L2] precursors. The [Co53-OH)2(salNO2ben)4]I·2(CH3)2CO and [Co53-OH)2(salClben)4]I·2DMF·CH2Cl2 compounds have been studied by X-ray methods and turn out to be isostructural. The structural data show that the cobalt atoms in the pentanuclear units are bridged by μ-O(phenolato) atoms and μ3-OH groups and approximate three types of co-ordination geometries: tetrahedral, octahedral and trigonal-bipyramidal. The X-ray structure of one proligand, namely 2,2′-[1,1-(4-nitrophenylmethanediyl)bis(nitrilomethylidene)diphenol] is also reported. The χT(T) behaviour of the complex with this ligand has been studied in the 4–300 K range. The data clearly show that ferromagnetic as well as (much weaker) antiferromagnetic exchange interactions occur within the cluster. A simple exchange model has been developed which nicely reproduces the experimental data.

Graphical abstract: New pentanuclear mixed valence Co(ii)–Co(iii) complexes of “short” salen homologues

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Publication details

The article was received on 27 Jun 2002, accepted on 15 Oct 2002 and first published on 14 Nov 2002


Article type: Paper
DOI: 10.1039/B206221F
Citation: J. Chem. Soc., Dalton Trans., 2002,0, 4672-4677
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    New pentanuclear mixed valence Co(II)–Co(III) complexes of “short” salen homologues

    B. Chiari, A. Cinti, O. Crispu, F. Demartin, A. Pasini and O. Piovesana, J. Chem. Soc., Dalton Trans., 2002, 0, 4672
    DOI: 10.1039/B206221F

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