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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]

The discrete multinuclear AgI−NHC complexes [Agn(1)n)](X)n; (n=3 or 4, X=BF4, PF6), synthesized from a bis‐NHC ligand 1 and AgI ions via multiligand self‐assembly, were observed to be in equilibrium between two forms (tri‐ and tetranuclear) in solution on the NMR timescale, which is unprecedented in CNHC‐donor based chemistry. The existence of both the species was confirmed by various studies such as NMR (1H, VT, 2D‐DOSY) and ESI‐MS analysis along with concentration studies. Importantly, replacing AgI with other coinage metals (AuI and CuI) was found to alter the phenomenon entirely: a slow exchange from the tetra‐ to trinuclear species was noticed for the AuI complexes (4 a, b), whereas no such process was detected in case of the CuI complexes (5 a, b). [ABSTRACT FROM AUTHOR]

The discrete multinuclear AgI−NHC complexes [Agn(1)n)](X)n; (n=3 or 4, X=BF4, PF6), synthesized from a bis‐NHC ligand 1 and AgI ions via multiligand self‐assembly, were observed to be in equilibrium between two forms (tri‐ and tetranuclear) in solution on the NMR timescale, which is unprecedented in CNHC‐donor based chemistry. The existence of both the species was confirmed by various studies such as NMR (1H, VT, 2D‐DOSY) and ESI‐MS analysis along with concentration studies. Importantly, replacing AgI with other coinage metals (AuI and CuI) was found to alter the phenomenon entirely: a slow exchange from the tetra‐ to trinuclear species was noticed for the AuI complexes (4 a, b), whereas no such process was detected in case of the CuI complexes (5 a, b). [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]