Cooperativity wins: Judiciously designed heterobimetallic conjugates of Ru(II) and Fe(II) metal centers have shown remarkable redox cooperativity to achieve living and well-defined acrylate polymers.

Abstract

Employing heterobimetallic complexes (HBCs) offers an exciting and powerful strategy for various catalytic applications. Here, we present an unorthodox synthetic route to synthesize a novel Ru^II-Fe^II heterobimetallic complex by implementing the strategy of “metalation with functionalization.” This complex utilizes a redox-assisted concerted strategy to facilitate the controlled radical polymerization (CRP) of acrylate monomers with significantly low catalyst loading. To understand the efficiency of the bimetallic catalyst over the other corresponding monometallic complexes, controlled polymerization experiments on acrylate monomers have been carried out. The redox cooperativity for efficient living CRP is very much pronounced and established in the Ru^II-Fe^II heterobimetallic dyad as evidenced by multiple orthogonal experimental results and the interesting rearrangement in the frontier molecular orbitals during catalysis steps. A plausible mechanistic pathway is proposed based on insights from electroparamagnetic resonance spectroscopy, cyclic voltametry, UV-Vis spectroscopy, rigid potential energy scans (PES), and the Fukui function. A modified atom transfer radical polymerization (ATRP) mechanism is offered by Ru^II-Fe^II conjugate, where redox-cooperativity and intramolecular electron transfer (IET) between the metal centers play a crucial role. This study investigates the potential of redox cooperativity in heterobimetallic systems, highlighting their efficacy as adaptable catalytic platforms.