Cluster-Based Networks: 1D and 2D Coordination Polymers Based on {MnFe2(μ3-O)}-Type Clusters

• Published in: Inorganic chemistry 2012-05, Vol.51 (9), p.5110-5117
• Main Authors: Dulcevscaia, Galina M, Filippova, Irina G, Speldrich, Manfred, van Leusen, Jan, Kravtsov, Victor Ch, Baca, Svetlana G, Kögerler, Paul, Liu, Shi-Xia, Decurtins, Silvio
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic202644t

A straightforward approach to heterometallic Mn–Fe cluster-based coordination polymers is presented. By employing a mixed-valent μ3-oxo trinuclear manganese(II/III) pivalate cluster, isolated as [MnIIMnIII 2O(O2CCMe3)6(hmta)3]·(solvent) (hmta = hexamethylenetetramine; solvent = n-propanol (1), toluene (2)) in the reaction with a μ3-oxo trinuclear iron(III) pivalate cluster compound, [Fe3O(O2CCMe3)6(H2O)3]O2CCMe3·2Me3CCO2H, three new heterometallic {MnIIFeIII 2} cluster-based coordination polymers were obtained: the one-dimensional polymer chain compounds {[MnFe2O(O2CCMe3)6(hmta)2]·0.5MeCN} n (3) and {[MnFe2O(O2CCMe3)6(hmta)2]·Me3CCO2H·(n-hexane)} n (4) and the two-dimensional layer compound {[MnFe2O(O2CCMe3)6(hmta)1.5]·(toluene)} n (5). Single-crystal X-ray diffraction analysis reveals a μ3-oxo trinuclear pivalate cluster building block as the main constituent in all polymer compounds. Different M:hmta ratios in 1–5 are related to the different structural functions of the N-containing ligand. In clusters 1 and 2, three hmta ligands are monodentate, whereas in chains 3 and 4 two hmta ligands act as bridging ligands and one is a monodentate ligand; in 5, all hmta molecules act as bidentate bridges. Magnetic studies indicate dominant antiferromagnetic interactions between the metal centers in both homometallic {Mn3}-type clusters 1 and 2 and heterometallic {MnFe2}-type coordination polymers 3–5. Modeling of the magnetic susceptibility data to a isotropic model Hamiltonian yields least-squares fits for the following parameters: J 1(MnII–MnIII) = −6.6 cm–1 and J 2(MnIII–MnIII) = −5.4 cm–1 for 1; J 1 = −5.5 cm–1 and J 2(MnIII–MnIII) = −3.9 cm–1 for 2; J 1(MnII–FeIII) = −17.1 cm–1 and J 2(FeIII–FeIII) = −43.7 cm–1 for 3; J 1 = −23.8 cm–1 and J 2 = −53.4 cm–1 for 4; J 1 = −13.3 cm–1 and J 2 = −35.4 cm–1 for 5. Intercluster coupling plays a significant role in all compounds 1–5.