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

摘要

The preparation of the sodium salt ofdicyano-acetic acid methyl ester (NaCH_3OC(O)C(CN)~ (NaL) is reported. The structure of this anion is related to the structure of the dicyanamide,whosc chelating capability has been used to develop 20 networks. Two new complexes of formula [M(L)_2(H_2O)_2J (M = Mn~(2+) {I) and Cu~(2+) (2) have be~n 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 ~2-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 bipyrarnidal, 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.