Cobalt(II) Coordination Polymer-Based Catalyst for Tandem Synthesis of Imines and CO ₂ Fixation for Synthesis of Cyclic Carbonates under Mild Conditions

Single crystals of a new cobalt(II)-based coordination polymer (CP), designated as <b>IITG-11</b> (IITG stands for Indian Institute of Technology), were solvothermally synthesized. The activated form of CP (<b>IITG-11a</b>) possesses coordinatively unsaturated Co(II) metal sites within its framework. <b>IITG-11a</b> exhibited excellent catalytic activity toward the tandem synthesis of imines via the oxidative coupling of benzyl alcohol with amine, achieving nearly 99% conversion within 18 h at 115 °C. Furthermore, <b>IITG-11a</b> was also explored as a heterogeneous catalyst for the coupling of epoxides with CO₂ into cyclic carbonates. Under ambient pressure in the presence of tetrabutylammonium bromide (TBAB) at 60 °C, <b>IITG-11a</b> facilitated the coupling between epichlorohydrin with CO₂ into their respective cyclic carbonate with a turnover number (TON) of 125 and a turnover frequency (TOF) of 10 h^-1. Moreover, the designed catalyst demonstrated a wide substrate scope for both organic transformations with reusability up to the fourth cycle. The stability of the catalyst was thoroughly investigated in the consecutive reuses. Plausible mechanisms for both catalytic cycles were proposed based on various control experiments and an extensive literature survey. These findings underscore the dual functionality of <b>IITG-11a</b> as a robust catalyst for both tandem imine synthesis and sustainable CO₂ fixation.