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)]_<i>n</i> (<b>CuI-BIBT</b>, BIBT = 4,7-di(1<i>H</i>-imidazole-1-yl)benzo[<i>c</i>][1,2,5]thiadiazole), [CuI(BPT)]_<i>n</i> (<b>CuI-BPT</b>, BPT = 1,4-bis(1<i>H</i>-imidazole-1-yl)benzene), [CuI(BTDB)]_<i>n</i> (<b>CuI-BTBD</b>, BTBD = 4,7-bis(1<i>H</i>-1,2,4-triazol-1-yl)benzo[<i>c</i>][1,2,5]thiadiazole), and [CuI(BTD)_0.5]_<i>n</i> (<b>CuI-BTD</b>, 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 Cu_<i>n</i>I_<i>n</i> chains. Their catalytic performance for the hydroboration of alkynes with bis(pinacolato)diboron (B₂Pin₂) was evaluated, revealing that <b>CuI-BIBT</b> and <b>CuI-BTD</b> exhibited superior activity, with <b>CuI-BTD</b> achieving a high TOF of 372 h^-1, while <b>CuI-BPT</b> and <b>CuI-BTDB</b> 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.