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 (NaC H3OC(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 us ed 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 structur es determined by single-crystal X-ray diffraction, The coordination geometr y of Mn atom in 1 is approximately octahedral, and the Mn atoms are mu (2)- bridgcd by two pails 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 bipyramida l, showing considerable Jahn-Teller distortion. Each copper atom is connect ed by four ligands to four different neighboring copper atoms, resulting in sheets of an infinite two-dimensional network. The large separation betwee n the paramagnetic centers in both compounds produces a weak antiferromagne tic interaction. (C) 2001 Elsevier Science B.V. All rights reserved.