Synthesis, crystal structure and magnetic properties of the malonato-bridged bimetallic chain [Mn(II)Cu(II)(mal)2(H2O)4]·2H2O

The first malonato-bridged bimetallic chain of formula [MnCu(mal)2(H2O)4]·2H2O (1) (H2mal=malonic acid) was prepared and its structure determined by X-ray diffraction methods. Each copper atom in 1 is in a square planar environment formed by four malonate-oxygens from two malonate ligands. The manganese atom is six-coordinated with four water molecules and two cis-coordinated malonate-oxygens from two malonate groups building a distorted octahedral surrounding. The malonate group acts simultaneously as bidentate and monodentate ligand towards copper and manganese atoms respectively, leading to a bimetallic chain. Two structurally different carboxylato-bridges exhibiting an anti–syn conformation alternate regularly within the chain, the intrachain copper–manganese separations being 4.790(1) and 5.209(1) Å. Its magnetic behaviour is typical of a ferrimagnetic Cu(II)Mn(II) bimetallic chain with intrachain antiferromagnetic coupling. The fully dehydrated phase of complex 1 exhibits an overall antiferromagnetic behaviour.