1D Coordination Polymers Constructed from anti−anti Carboxylato-Bridged Mn^III₃O(Brppz)₃ Units: From Long-Range Magnetic Ordering to Single-Chain Magnet Behaviors

The coordination of methanol and ethanol molecules was observed in the construction of three 1D coordination polymers composed of anti−anti carboxylato-bridged MnIII3O(Brppz)3 units [Brppz = 3-(5-bromine-2-phenolate)pyrazolate]. The difference in these 1D complexes’ structures induced by methanol and ethanol solvents leads to the variation of the magnetic properties. The methanol solvent product 1 [MnIII3O(Brppz)3(MeOH)3(AcO)]·0.5MeOH has a MnIII3O repeating unit with two octahedral configuration manganese(III) ions and one square-pyrimid configuration manganese(III) ion, showing a long-range magnetic ordering with a Tc of 8.2 K, whereas the ethanol solvent products 2 [MnIII3O(Brppz)3(C2H5OH)4(AcO)] (α-phase) and 3 [MnIII3O(Brppz)3(C2H5OH)4(AcO)] (β-phase) are polymorphs, both having a MnIII3O repeating unit with three octahedral configuration manganese(III) ions, displaying single-chain magnet behaviors. Products 2 and 3 represent the first examples of polymorphs of single-chain magnets. Furthermore, the bridging carboxylate ligand in these 1D complexes was generated by the decomposition of β-diketones via the retro-Claisen condensation reactions in the presence of strong bases.