A new complex of manganese(II) with L-alpha-alanine: structure, spectroscopy and thermal study

A polynuclear manganese(II) complex of L-alpha-alanine of the formula [Mn-4 (ala)(4)Cl-7(H2O)(5)]Cl . 3H(2)O (where ala=L-alpha-alanine) has been synth esized and characterized. An X-ray crystallographic study shows that the po lymer consists of double linear chains. One chain contains alternately loca ted Mn(1) and Mn(2) ions, and the other chain is built of Mn(3) and Mn(4) i ons. Each independent manganese(II) ion is in an octahedral arrangements. M n(1), Mn(2) and Mn(3) atoms display the same coordination environment being surrounded by two carboxylate oxygen atoms of alpha-alanine molecules, thr ee chloride ions and one aqua ligand. In the coordination octahedron of the Mn(4) atom one chloride ion is replaced by a water molecule. In chains Mn( II) ions are joined alternately by a chloride ion or by two carboxylate bri dges from different alpha-alanine molecules and one Cl- ion. Three non-coor dinated water molecules and one chloride ion are located between the chains . The crystal structure is stabilized by an extensive system of hydrogen bo nds. Thermogravimetric analysis shows this complex is stable to 353 K, Upon heating the complex loses molecules of water and is transformed into the s uitable oxides, The IR spectra of free ligand and complex have been discuss ed. (C) 1999 Elsevier Science Ltd. All rights reserved.