Constructing anhydrous halide bridged manganese(II) clusters: Synthesis, structures and magnetic properties

Abstract

The reaction of Mn0 and HgCl2 with triphenylacetic acid in a mixture of 2-methoxyethanol and toluene afforded complex [Mn2IICl2(O2CCPh3)2(2-methoxyethanol)3] (1) in very good yield. Repeating the same reaction and replacing 2-methoxyethanol with THF forms the complex [Mn3IICl3.04(O2CCPh3)1.96(2-methoxyethanol)(THF)4] (2) in good yield. Furthermore the reaction between Mn0 and triphenylacetic acid in a mixture of THF and toluene after heating produces the complex [Mn4Cl5Na(O2CCPh3)4(THF)6] (3). Finally, the reaction between MnCl2 and potassium triphenylacetate or lithium triphenylacetate in THF and toluene gave complexes [Mn4Cl5K(O2CCPh3)4(THF)6] (4) and [Mn4Cl5Li(O2CCPh3)4(THF)5]·0.75(THF) (5·0.75THF), respectively, in good yields. The crystal structures of 1–5 have been determined by single-crystal X-ray crystallography. Complex 1 is a chloride bridged [MnII2] dimer in which the two metal ions are found in an O5Cl and an O3Cl2 coordination environment. Complex 2 is a trinuclear [MnII3] triangle-like cluster in which the “central” MnII ion is bridged via two chloride ions to the peripheral Mn2+ ions, additionally all manganese ions are connected by oxygen ion in a μ3 mode. Complexes 3–5 are all tetranuclear [MnII4Cl5]3+ metallic clusters displaying similar geometries, in which the tetrametallic core unit possesses a planar square arrangement. DC magnetic susceptibility studies indicate the presence of dominant antiferromagnetic exchange for all 1–4 clusters.