We report the synthesis, structures and magnetic properties of a series of chromium(iii) metal-centered triangle (or "star") clusters, [Cr 4RC(CH2O)32(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 [Cr4EtC(CH2O)32NH(C(R) NH)22Cl6] (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
Batchelor, L., Sander, M., Tuna, F., Helliwell, M., Moro, F., Van Slageren, J., et al. (2011). Chromium(iii) stars and butterflies: Synthesis, structural and magnetic studies of tetrametallic clusters. DALTON TRANSACTIONS, 40(19), 5278-5284 [10.1039/c1dt10172b].
Chromium(iii) stars and butterflies: Synthesis, structural and magnetic studies of tetrametallic clusters
Moro, Fabrizio;
2011
Abstract
We report the synthesis, structures and magnetic properties of a series of chromium(iii) metal-centered triangle (or "star") clusters, [Cr 4RC(CH2O)32(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 [Cr4EtC(CH2O)32NH(C(R) NH)22Cl6] (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
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