Crystal and molecular structure of aquadibromo[2-(2-pyridyl)quinolinyl]manganese(II), and the relation between structure and magnetic properties of manganese(II) complexes

Abstract

The crystal and molecular structure of the title complex has been determined by heavy-atom techniques. Crystal are monoclinic, a= 8.172(3), b= 11.868(4), c= 16.456(5)Å, β= 98.83(4)°, space group P2₁/c. The structure was refined by least squares to R 8% for 1 577 reflections measured by diffractometer. The complex consists of well-isolated units of five-co-ordinated Mn^II molecules. permitting no significant magnetic exchange interaction between neighbouring paramagnetic centres. Comparison with a related structure [Mn₂(biq)₂Cl₄](biq = 2.2′-biquinolyl) indicates that the presence of the co-ordinated water molecule (Mn–O 2.27 Å) prevents dimerisation of the complex via bromide bridges. The MnN₂X₂(X = Br or Cl) chromophore in this type of complex seeks out an extra ligand to become distorted trigonal bipyramidal five-co-ordinate.