Zirconium oxo clusters as discrete molecular catalysts for the direct amide bond formation

Abstract

Zirconium compounds are prime catalysts in organic synthesis; however, their utility is often diminished by their sensitivity to ambient conditions. Although zirconium oxo clusters have been extensively explored in the...

Fatty acid capped, metal oxo clusters as the smallest conceivable nanocrystal prototypes

“…[12][13][14][15] Composites with improved strength are produced by incorporating zirconium oxo clusters into polymers. 16,17 Zirconium and hafnium oxo clusters are used as catalysts to make or break amide bonds, 18,19 and they are suitable as inorganic extreme-ultraviolet photoresists. 20,21 Subtle differences in cluster chemistry between Zr and Hf are exploited in the industrial separation of Zr from Hf.…”

Nonaqueous Chemistry of Group 4 Oxo Clusters and Colloidal Metal Oxide Nanocrystals

“…Improved performance was achieved using Zr4 –methacrylate clusters and incorporating polymer composites. ,, On the other hand, Hf 18 O 10 (OH) 26 (SO 4 ) 13 ·(H 2 O) 33 clusters were used as heterogeneous catalysts for the selective hydrolysis of proteins . Recently, the discrete Zr12 -acrylate cluster has been used as air and moisture stable molecular catalyst for the formation of amide bonds . It is an exciting development that discrete, soluble clusters are being exploited, in contrast to clusters immobilized in MOFs.…”

“…24 Recently, the discrete Zr12-acrylate cluster has been used as air and moisture stable molecular catalyst for the formation of amide bonds. 258 It is an exciting development that discrete, soluble clusters are being exploited, in contrast to clusters immobilized in MOFs.…”

Dynamic environment at the Zr6 oxo cluster surface is key for the catalytic formation of amide bonds

“…A dodecanuclear ZrOC composed of two Zr 6 O 8 units, [Zr 6 (OH) 4 O 4 (OAcr) 12 ] 2 (OAcr = acrylate) ( Zr 12 ), catalyzed the direct formation of amide bonds, remarkably without requiring water scavenging or anhydrous conditions. 24 Considering the difficulties faced on elucidating molecular aspects of the reactivity in our previous work with Zr-MOF catalysts, 25 this pioneer work on Zr 12 prompted us to explore more of the fundamental reactivity of Zr 6 O 8 clusters without common constrains arising from the heterogeneous nature of MOFs ( e.g. , diffusion of substrates and products), leveraging the possibility of investigating them as discrete molecular species for the catalytic direct intermolecular formation of amide bonds.…”