Abstract
The N,O‐chelate ligands 2‐(iminoethyl)pyridine N‐oxide (2a) and 2‐(iminoethyl)‐6‐isopropylpyridine N‐oxide (2b) were prepared by conventional synthetic routes, the latter involving a variant of the Reissert–Henze reaction. Treatment of 2a with FeCl~2~ resulted in a deoxygenation reaction of the ligand and formation of the salt [bis{2‐(iminoethyl)pyridine}FeCl]^+^[FeCl~4~]^–^ (18a). In contrast, the reaction of 2a with PdCl~2~ or CoCl~2~ cleanly furnished the six‐membered chelate [κ__N__,O‐2(iminoethyl)pyridine N‐oxide]MCl~2~ complexes (19a, M = Pd) or (20a, M = Co), respectively, which were both characterised by X‐ray diffraction. Treatment of 2b with [NiBr~2~(dme)], followed by crystallisation from THF, gave the complex [(κ__N__,O‐2b)NiBr~2~(THF)] (21b), which features a distorted trigonal‐bipyramidal coordination geometry of the central metal atom. The reaction of 2a with [NiBr~2~(dme)] gave the structurally related complex [(κ__N__,O‐2a)NiBr~2~(κ__O__‐2a)] (21a). The N,O‐chelate Pd complex 19a was shown to be an active catalyst for the Suzuki coupling reaction. The ligand systems 2a,b and their related 2‐(iminoethyl)pyridines 3a,b and a variety of metal complexes of ligands 3 were also prepared and characterised for comparison by X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)