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The bis(azolium) salt [L1‐H2]Br2 was found to serve as a suitable platform for accessing the heterobimetallic IrIII‐M (M=PdII/AuI) and PdII‐IrIII complexes. Initially, selective mono‐metalation of [L1‐H2]Br2 yielded an orthometalated IrIII‐ or non‐orthometalated PdII‐complex. Sequential metalation of the mono‐IrIII complex resulted in the formation of heterobimetallic IrIII‐PdII/AuI complexes. Similarly, a distinct heterobimetallic PdII‐IrIII complex was synthesized starting from the mono‐PdII complex. Further, the corresponding homobimetallic IrIII‐IrIII and PdII‐PdII complexes were directly obtained from [L1‐H2]Br2. Additionally, monometallic PdII and IrIII analogues were synthesized from [L2‐H]Br and [L3‐H]Br, respectively. The heterobimetallic IrIII‐PdII and PdII‐IrIII complexes were then evaluated as catalysts in various one‐pot tandem catalytic reactions in which they demonstrated superior activity than the mixtures of both their corresponding homobimetallic IrIII‐IrIII/PdII‐PdII and monometallic IrIII/PdII counterparts, under the constant concentrations of metal centers. Moreover, while comparing complexes IrIII‐PdII and PdII‐IrIII, the former exhibits higher activity in all the studied reactions. All these findings suggest the presence of some form of cooperativity between the two metal centers (Ir and Pd) connected by a single ligand framework in IrIII‐PdII and PdII‐IrIII complex, with IrIII‐PdII displaying better cooperativity that has been validated by electrochemical, NMR, and DFT studies. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis and catalytic activity of heterobimetallic complexes bridged by an unsymmetrical bis(NHC) ligand. The complexes, IrIII−M (M=PdII/AuI), were found to exhibit enhanced catalytic activity in one-pot tandem catalytic reactions compared to homobimetallic and monometallic catalysts. The improved activity was attributed to better communication and cooperativity between the two different metal centers, as supported by NMR, electrochemical, and theoretical studies. The full research article provides more detailed information on this topic. [Extracted from the article]