A Deep cavitand receptor functionalized with Fe(II) and Mn(II) aminopyridine complexes for bioinspired oxidation catalysis

Abstract

A deep cavitand receptor 2 based on a resorcinarene scaffold and functionalized with a bis(pyridyl)dipyrrolidine tetradentate ligand has been obtained. Binding of divalent metal ions (M2+ = Mn2+, Fe2+, and Zn2+) at the tetradentate ligand results in the formation of cavitand complexes 2·M(OTf)2. The complexes exhibit selective binding of alkylammonium ions and amides within the cavitand. 2·M(OTf)2 (M = Fe(II) and Mn(II)) catalyze selective hydroxylation of aliphatic C-H bonds and epoxidation of olefins with hydrogen peroxide, exhibiting selectivity patterns consistent with the implication of high valent metal-oxo species. Furthermore, 2·Fe(OTf)2 reacts with IO4- to form an oxoiron(IV) complex [2·Fe(O)]2+, without decomposition of the supramolecular container. This species is relatively stable at 0 °C, yet engages in fast oxygen-atom-transfer reactions