Designing Copper(I) Iodide Clusters with Tunable D−π–A Ligands for Photocatalytic Thiocyanation

Text：Five D-π-A ligands and six copper(I) iodide complexes [Cu I n I n (L m ) n ] (m = 1-5, n = 2, 4) are designed for the study of photocatalytic thiocyanation of the C(sp 2 )–H bonds in arenes and heteroarenes. The findings suggest that the four nuclear [Cu I 4 I 4 (L 4 ) 4 ] cluster is of better effect on photocatalysis with reference to its superior light-harvesting ability and multi-electron transfer capability owing to its unique tetranuclear configuration. Thus, a synthesis of aryl thiocyanates by photoredox thiocyanation of anilines, phenols, and heteroarenes with NH 4 SCN is reported. The reactions proceed smoothly in air atmosphere at room temperature. The scope of the method is demonstrated with 24 examples with the yield up to 85%. The mechanism is proposed to involve a single-electron transfer process mediated by the photoexcited copper(I) cluster, generating a thiocyanato radical (SCN·) and initiating the subsequent radical pathway. The successful gram-scale synthesis demonstrates the practical utility and potential of this strategy for constructing aryl thiocyanates.