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.