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

## TL;DR

This paper describes the synthesis and structural analysis of iron(II) and manganese(II) complexes with a specific ligand, revealing their coordination geometries and stability.

## Contribution

The study reports the synthesis and structural characterization of new iron(II) and manganese(II) complexes with a coplanar tridentate ligand.

## Key findings

- Iron(II) and manganese(II) dichlorido complexes with the ligand L were synthesized and structurally analyzed.
- The bis-chelate iron(II) complex [Fe(L)2](PF6)·5(thf) was synthesized and authenticated.
- The dichlorido complexes displayed distorted trigonal pyramidal structures in the solid state.

## Abstract

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-1H-pyrazole-3-yl)pyridine (denoted as L), its iron(II) and manganese(II) dichlorido complexes, and its bis-chelate iron(II) complexes, viz. [FeCl2(L)]·2(MeOH) and [MnCl2(L)]·2(MeOH), and [Fe(L)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(L)]·2(MeOH) and [MnCl2(L)]·2(MeOH) displayed distorted trigonal pyramidal structures in the solid state. However, [FeCl2(L)]·2(MeOH) was not stable in methanol and formed the bis-chelate iron(II) complex [Fe(L)2](FeCl4). Therefore, the bis-chelate iron(II) complex [Fe(L)2](PF6)·5(thf) was also synthesized and structurally and spectroscopically authenticated.