A thiolated copper-hydride nanocluster with chloride bridging as a catalyst for carbonylative C–N coupling of aryl amines under mild conditions: a combined experimental and theoretical study

Abstract

Atomically precise copper nanoclusters (Cu NCs), an emerging class of nanomaterials, have garnered significant attention owing to their versatile core–shell architecture and their potential applications in catalytic reactions. In this study, we present a straightforward synthesis strategy for [Cu₂₉(S^tBu)₁₂(PPh₃)₄Cl₆H₁₀][BF₄] (Cu₂₉) NCs and explore their catalytic activity in the carbonylative C–N coupling reaction involving aromatic amines and N-heteroarenes with dialkyl azodicarboxylates. Through a combination of experimental investigations and density functional theory studies, we elucidate the radical mechanisms at play. The crucial step in the catalytic process is identified as the decomposition of diisopropyl azodicarboxylates on the surface of Cu₂₉ NCs, leading to the generation of oxyacyl radicals and the liberation of nitrogen gas. Subsequently, an oxyacyl radical abstracts a hydrogen atom from aniline, initiating the formation of an aminyl radical. Finally, the aminyl radical reacts with another oxyacyl radical, culminating in the synthesis of the desired carbamate product. This detailed analysis provides insights into the intricate catalytic pathways of Cu₂₉ NCs, shedding light on their potential for catalyzing carbonylative C–N coupling reactions.