Dual‐Cation Fe/Zn Complexes and Their Catalysis Effects on Polyurethane Synthesis

Replacing toxic organotin catalysts in polyurethane (PU) synthesis remains a critical challenge, as current alternatives suffer from either low activity or diminished product performance. Herein, we report a new class of dual‐cation Fe/Zn complexes through strategic integration of imidazolium frameworks with transition metal centers, characterized by FT‐IR, nuclear magnetic resonance (NMR) spectroscopy, and single crystal X‐ray diffraction (SC‐XRD). These catalysts exhibit activities higher than commercial organotin and tertiary amines while maintaining excellent biocompatibility as well. Mechanistic investigations establish a 7.4‐fold enhancement in conversion rates through synergistic cooperation, as imidazolium cations and Zn 2+ centers both activate isocyanate groups, while coulombic repulsion between cationic moieties effectively prevents metal aggregation. This work provides both a sustainable alternative to tin catalysts for PU synthesis and a general design principle for multifunctional polymerization catalysis strategies.