New macrocyclic Schiff-base complexes incorporating a phenanthroline unit. Part 2: Template synthesis of some manganese(II) complexes and crystal structure studies

A series of Mn(II) macrocyclic Schiff-base complexes [MnLn]2+ have been prepared via the Mn(II) templated [1+1] cyclocondensation of 2,9-dicarboxaldehyde-1,10-phenanthroline with appropriate linear and branched amines. In this way ligands the pentaaza macrocycle L1 which is 15-membered and L2 which is 16-membered possessing no pendant arm, L6 is 15-membered with one 2-aminoethyl pendant arm and L8 which is 18-membered hexaaza macrocycle with two 2-aminoethyl pendant arms are formed. All the complexes have been characterized using spectroscopic methods. The crystal structures of [MnL8](ClO4)2 · EtOH were determined and indicate that in the solid state the complex adopts a slightly distorted hexagonal bipyramid geometry with the Mn(II) ion located within a hexaaza macrocycle with the two pendant amines coordinating in the axial positions.

Graphical abstractA series of Mn(II) macrocyclic Schiff-base complexes [MnLn]2+ have been prepared via the Mn(II) templated [1+1] cyclocondensation of 2,9-dicarboxaldehyde-1,10-phenanthroline with appropriate linear and branched amines.Three of the ligands are based on a pentaaza macrocycle L1 and L2 are 15- and 16-membered, respectively, and possesses no pendant arms; L6 is 15-membered with one 2-aminoethyl pendant arm and L8 is an 18-membered hexaaza macrocycle with two 2-aminoethyl pendant arms.Figure optionsDownload full-size imageDownload as PowerPoint slide