<p>A series of [2 × 2] square lattice rare earth complexes Nd₄L₄ (1), Pr₄L₄ (2), and Eu₄L₄ (3) with Schiff base ligands were synthesized. The precise molecular structure of the complex was determined by single crystal X-ray diffraction analysis. The chemical composition, phase purity and thermal stability of the complexes were systematically studied by infrared spectroscopy (IR), nuclear magnetic resonance (NMR), powder X-ray diffraction (PXRD), elemental analysis (EA) and thermogravimetric analysis (TGA). The results show that these complexes not only have excellent thermal stability, but also are rich in multiple rare earth metal active centers in the structure, providing abundant active sites for catalytic reactions. The catalytic results show that they not only have mild reaction conditions but also show excellent catalytic performance, with satisfactory conversion rate and good turnover frequency (TOF, value up to 6625&#xa0;h⁻¹). These results indicate that polynuclear lanthanide complexes have great power as catalysts for the chemical fixation of CO₂, which provides some new idea s for the design of efficient catalysts in this field.</p> Graphical Abstract <p>Entry for the Table of Contents: With the increase of CO₂ emissions, there is an urgent need for breakthrough solutions to address the issue of CO₂ balance in the atmosphere. Converting CO₂ into high value-added products is of great significance for reducing emissions. This study synthesized a novel class of Schiff base lanthanide complexes, which were used as catalysts for the chemical fixation of CO₂ into cyclic carbonates and exhibited excellent performance.</p> <p></p>