The reactivity and selectivity of non-hemeF e II complexes as oxidationc atalysts can be substantially modified by alteration of the ligand backbone or introductiono f various substituents. In comparison with the hexadentate ligand2 )h as am ethyl group on two of the four picolyl positions. Fe II complexation by 2Me L 6 2 yields two diastereomericc omplexes with very similars tructures, which only differ in the axial/equatorial positions occupied by the methylated pyridylg roups.I ns olution, these two isomers exhibit different magnetic behaviors. Whereas one isomer exhibits temperature-dependent spin-state conversion betweent he S = 0a nd S = 2s tates, the other is more reluctant towards this spin-statee quilibrium and is essentially diamagnetic at room temperature. Their catalytic properties for the oxidation of anisole by H 2 O 2 are very different and correlate with their magnetic properties,w hich reflect their lability/inertness. These different properties most likely depend on the different steric constraintso ft he methylated pyridyl groups in the two complexes.

Eight cobalt‐salen complexes have been covalently attached to a calix[8]arene platform through a flexible linker by a procedure employing Click chemistry. The corresponding well‐defined catalyst proved its efficiency in the hydrolytic kinetic resolution (HKR) of various epoxides through an operative bimetallic cooperative activation, demonstrating highly enhanced activity when compared to its monomeric analogue. As an insoluble complex, this multisite cobalt‐salen catalyst could be easily recovered and reused in successive catalytic runs. Products were isolated by a simple filtration with virtually no cobalt traces and without requiring a prior purification by flash chromatography.