Synthesis, structure and magnetic properties of Mn(II) and Cu(II) complexes with the dicyano-acetic acid methyl ester anion

The preparation of the sodium salt of dicyano-acetic acid methyl ester (NaCH3OC(O)C(CN)2) (NaL) is reported. The structure of this anion is related to the structure of the dicyanamide, whose chelating capability has been used to develop 2D networks. Two new complexes of formula [M(L)2(H2O)2] (M=Mn2+ (1) and Cu2+ (2)) have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. The coordination geometry of Mn atom in 1 is approximately octahedral, and the Mn atoms are μ2-bridged by two pairs of L− resulting in an infinite one-dimensional chain. Two types of hydrogen bonds link the chains within a 3-dimensional infinite lattice. The coordination geometry of copper in 2 is tetragonal bipyramidal, showing considerable Jahn–Teller distortion. Each copper atom is connected by four ligands to four different neighboring copper atoms, resulting in sheets of an infinite two-dimensional network. The large separation between the paramagnetic centers in both compounds produces a weak antiferromagnetic interaction.