Iron(II) and Manganese(II) Coordination Chemistry Ligated by Coplanar Tridentate Nitrogen-Donor Ligand, 2,6-bis(5-isopropyl-1H-pyrazol-3-yl)pyridine

Coplanar tridentate nitrogen-donor ligands have been extensively employed to stabilize transition metal complexes by chelation. Some complexes exhibit interesting structures and photoluminescent properties. In this work, 2,6-bis(5-isopropyl-1<i>H</i>-pyrazole-3-yl)pyridine (denoted as <b>L</b>), its iron(II) and manganese(II) dichlorido complexes, and its bis-chelate iron(II) complexes, <i>viz</i>. [FeCl₂(<b>L</b>)]·2(MeOH) and [MnCl₂(<b>L</b>)]·2(MeOH), and [Fe(<b>L</b>)₂](PF₆) ·5(thf), respectively, were synthesized and characterized by single-crystal X-ray structural analysis. These solid-state structures contained N-H donors that formed hydrogen bonds with the coordinated halogenide ions and lattice solvent molecules, methanol or tetrahydrofuran. The iron(II) and manganese(II) dichlorido complexes [FeCl₂(<b>L</b>)]·2(MeOH) and [MnCl₂(<b>L</b>)]·2(MeOH) displayed distorted trigonal pyramidal structures in the solid state. However, [FeCl₂(<b>L</b>)]·2(MeOH) was not stable in methanol and formed the bis-chelate iron(II) complex [Fe(<b>L</b>)₂](FeCl₄). Therefore, the bis-chelate iron(II) complex [Fe(<b>L</b>)₂](PF₆)·5(thf) was also synthesized and structurally and spectroscopically authenticated.