Two seven-coordinate Mn(II) complexes derived from pentadentate ligands: Structural characterization and investigation of photophysical properties

Two mononuclear Mn(II) complexes derived from pentadentate ligands were prepared and characterized. Molecular structures of the complexes were determined by X-ray diffraction studies. Mn(II) ions in both structures are seven-coordinate with approximate pentagonal bipyramidal geometry where the pyridinediimine unit and phenolic or alcoholic oxygen atoms (N₃O₂) of the ligand are located at the pentagonal plane and two exogenous ligands at the axial positions. In the structure of [Mn(HL₂)Cl(CH₃OH)]·2(CH₃OH), methanol solvates link complex molecules into a 1D hydrogen-bonded chain. Emission spectra of the complexes show only one emission band in the 595–625 nm range upon excitation in the 585–615 nm range.