Six- and seven-co-ordinate manganese(II) complexes of Schiff-base ligands derived from the condensation of 2,6-diacetylpyridine with ethanolamine (L1) or propanolamine (L2); X-ray crystal structures of [MnL1Cl2]·H2O and [{MnL2(NCS)2}x]

Abstract

Four seven-co-ordinate manganese(II) complexes containing the ligand 2,6-bis[1-(2-hydroxyethylimino)ethyl]pyridine (L¹) have been synthesised by Schiff-base condensation of 2,6-diacetylpyridine and ethanolamine in the presence of Mn²⁺. A six-co-ordinate complex containing 2,6-bis[1-(3-hydroxypropylimino)ethyl]pyridine (L²) was obtained when the amine reagent was propanolamine. These complexes have been characterised by analytical, spectroscopic, magnetic, conductance, and single-crystal X-ray diffraction methods. Crystal data: [MnL¹Cl₂]·H₂O (2), triclinic, a= 8.322(6), b= 8.465(5), c= 12.935(9)Å, α= 72.82(5), β= 72.20(6), γ= 81.38(5)°[{MnL²(NCS)₂}_x](5), monoclinic, a= 14.387(3), b= 10.045(2), c= 15.528(4)Å, and β= 115.10(2)°. The unusual seven-co-ordination observed is discussed in relation to the flexible non-cyclic ligands employed.