Synthesis, structure and magnetic properties of new polymeric compounds containing manganese(II) Pzdc (PzdcH2: 2,3-pyrazinedicarboxylic acid)

When 2,3-pyrazinedicarboxylic acid (PzdcH(2)) reacts separately with two manganese(II) salts: MnCl2 and Mn(OAc)(2) in aqueous solution, two different products are obtained: a mononuclear complex Mn(Pzdc)(2). 2H(2)O and a polymeric complex [MnPzdc(H2O)(2). 2H(2)O](n) which has been determined by X-ray diffraction at room temperature. The manganese atoms are located in a distorted octahedral coordination environment with two oxygen atoms O(5), O(6) from two water molecules, the other three oxygen atoms O(I), O(3a), O(4a) from carboxylate groups of three adjacent 2,3-pyrazinedicarboxylate anions and one nitrogen atom N(1) from the 2,3-pyrazinedicarboxylic acid. Therefore, the infinite 'ladder-like' chains consisting of Mn2+ and the Pzdc dianion are formed. The ladder-like chains are linked together with hydrogen bonds from coordinated and uncoordinated water molecules. The magnetic susceptibilities of the two manganese complexes have been determined over the temperature range 1.5-300 K. The study of magnetic properties shows that there is a weak antiferromagnetic interaction between two metal ions in the complex [MnPzdc(H2O)(2). 2H(2)O](n), but a paramagnetic behavior in MnPzdc(H2O)(2). (C) 1999 Elsevier Science Ltd. All rights reserved.