Benzothiadiazole Ligand Modulation of Cu(I)-Based Coordination Polymers to Regulate Catalytic Properties for the Hydroboration of Alkynes.

In this work, four novel Cu(I)-based coordination polymers with the formulas of [CuI(BIBT)]n (CuI-BIBT, BIBT = 4,7-di(1H-imidazole-1-yl)benzo[c][1,2,5]thiadiazole), [CuI(BPT)]n (CuI-BPT, BPT = 1,4-bis(1H-imidazole-1-yl)benzene), [CuI(BTDB)]n (CuI-BTBD, BTBD = 4,7-bis(1H-1,2,4-triazol-1-yl)benzo[c][1,2,5]thiadiazole), and [CuI(BTD)0.5]n (CuI-BTD, BTD = benzothiadiazole) were synthesized by the reactions of the corresponding ligand with CuI. All four Cu(I)-based coordination polymers featured two-dimensional (2D) coordination networks built from the organic ligands and Cu2I2 clusters or CunIn chains. Their catalytic performance for the hydroboration of alkynes with bis(pinacolato)diboron (B2Pin2) was evaluated, revealing that CuI-BIBT and CuI-BTD exhibited superior activity, with CuI-BTD achieving a high TOF of 372 h-1, while CuI-BPT and CuI-BTDB showed a much lower efficiency. The significant activity differences underscore the critical role of ligand electronic properties: moderate electron-withdrawing of organic ligands enhances catalysis by reducing Cu+ surface charge density, facilitating product desorption, and improving efficiency. However, excessively strong electron-withdrawing effects of organic ligands weaken Cu-substrate interactions, diminishing the catalytic performance.