Chromium(iii) stars and butterflies: Synthesis, structural and magnetic studies of tetrametallic clusters

Luke J. Batchelor, Mario Sander, Floriana Tuna, Madeleine Helliwell, Fabrizio Moro, Joris Van Slageren, Enrique Burzurí, Oscar Montero, Marco Evangelisti, Fernando Luis, Eric J L McInnes

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We report the synthesis, structures and magnetic properties of a series of chromium(iii) metal-centered triangle (or "star") clusters, [Cr 4{RC(CH2O)3}2(4,4′- R′2-bipy)3Cl6] [R = Et, R′ = H (2); R = HOCH2, R′ = H (3); R = Et, R′ = tBu (4)], prepared by two-step solvothermal reactions starting from [CrCl 3(thf)3]. The product of the first stage of this reaction is the salt [Cr(bipy)2Cl2]2[Cr 2Cl8(MeCN)2] (1). In the absence of the diimine, a different family of tetrametallics is isolated: the butterfly complexes [Cr4{EtC(CH2O)3}2{NH(C(R) NH)2}2Cl6] (R = Me (5), Et (6), Ph (7)] where the chelating N-acetimidoylacetamidine NH(C(R)NH)2 ligands are formed in situ via condensation of the nitrile solvents (RCN) under solvothermal conditions. Magnetic measurements show the chromium stars to have an isolated S = 3 ground state, arising from antiferromagnetic coupling between the central and peripheral metal ions, analogous to the well-known Fe(iii) stars. Bulk antiferromagnetic ordering is observed at 0.6 K. The butterfly complexes have a singlet ground state, with a low-lying S = 1 first excited state, due to dominant wing-body antiferromagnetic coupling. © 2011 The Royal Society of Chemistry.
    Original languageEnglish
    Pages (from-to)5278-5284
    Number of pages6
    JournalDalton Transactions
    Volume40
    Issue number19
    DOIs
    Publication statusPublished - 21 May 2011

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