Multi-Metallic Complexes Supported by Pyrazolate Ligands and their Affinity for NO

Graham de Ruiter, Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States
Theodor Agapie, Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States

The biochemical processing of a wide variety of gasses including, H2, N2, CO2, CO and NOx requires complex machinery. Metalloenzymes are highly specialized in such transformations, and often employ multi-metal cooperativity. However controlling the assembly of multiple metals into a single organized framework remains a challenge. Recently we demonstrated that multi-dentate ligands can support clusters that mimic the structural topology of the oxygen evolving complex (OEC) in photosystem II (PSII). This ligand framework - consisting of a 1,3,5-triarylbenzene core decorated with dipyridyl-alcohol moieties - supports a large variety of metal clusters. Towards expanding the scope of our previously prepared clusters, we utilized pyrazolate-type ligands that allow for formation of tetra-metallic clusters with vacant coordination sites. The coordination modes with first-row transition metals and the reactivity of these multi-metallic complexes will be discussed. Especially the effect of the redox-state on binding of small molecules such as NO will be presented.