Synthesis and characterization of new neutral Mn(I) tricarbonyl complexes with 8‐hydroxyquinoline and imidazole ligands as CO releasing molecules

Abstract

A series of manganese(I) tricarbonyl complexes formulated as [Mn(8‐HQ)(CO)3Imd] (HQ = hydroxyquinoline and Imd = imidazole derivatives) was synthesized and fully characterized. These structures could be easily accessed from a common dimeric edifice formulated as [Mn2(8‐HQ)2(CO)6]. The structure of this complex has been confirmed by X‐ray diffraction studies. Its reaction with a range of imidazole derivatives (Imd) yielded the monomeric complexes [Mn(8‐hydroxyquinoline)(CO)3Imd] with various functional groups as an anchoring point for a vector. Photoactivation of all these complexes by blue‐light irradiation led to the liberation of 3 mol of CO per mol of complex as determined experimentally. Spectroscopic and computational methods were employed to explore the mechanism of CO release. Finally, a manganese complex including the more elaborate imidazole ligand N‐ and C‐di‐protected histidine was successfully synthesized, opening the way to its direct incorporation in peptides.