Pyridylmethylamines as Ligands in Iron Halide Complexes – Coordination Behaviour Depending on the Halide, the Denticity of the Amino Ligand and the Oxidation State of Iron

Abstract

Abstract2‐Pyridylmethylamine (amp) and 8‐aminochinoline (ach) readily form the following complexes with iron halides in methanol: [(amp)2FeCl2] (1a), [(amp)2FeBr2] (1b), [(ach)2Fe(MeOH)2]Br2 (1c), and [(amp)FeCl2(μ‐OMe)]2 (2). Methanol was chosen as a solvent because these reactions are rather complex in ether. For example, FeCl3 forms the ionic complex pair [(dme)2FeCl2] [FeCl4] (3) with 1,2‐dimethoxyethane (dme). The reaction of FeBr2 with tridentate di(2‐pyridylmethyl)amine (dpa) and tetradentate 1,2‐dipyridyl‐1,2‐diaminoethane (dpdae) yields the complexes [(dpa)2Fe]Br2·2 MeOH (4) and [(dpdae)2Fe] [FeBr4] (5), respectively. Crystallographic and magnetochemical investigations show the high‐spin configuration for the complexes 1 and 2, whereas the short Fe‐N distances of 4 clearly indicate a low‐spin state. Compound 2 exhibits an antiferromagnetic exchange interaction with a coupling constant J = −29.4 cm−1 (H;af = −J S;afA·S;afB).