| Summary: | A series of mixed bis-NHC rhodium(I) complexes of type RhCl(η<sup>2</sup>-olefin)(NHC)(NHC’) have been synthesized by a stepwise reaction of [Rh(<i>μ</i>-Cl)(η<sup>2</sup>-olefin)<sub>2</sub>]<sub>2</sub> with two different NHCs (NHC = N-heterocyclic carbene), in which the steric hindrance of both NHC ligands and the η<sup>2</sup>-olefin is critical. Similarly, new mixed coumarin-functionalized bis-NHC rhodium complexes have been prepared by a reaction of mono NHC complexes of type RhCl(NHC-coumarin)(η<sup>2</sup>,η<sup>2</sup>-cod) with the corresponding azolium salt in the presence of an external base. Both synthetic procedures proceed selectively and allow the preparation of mixed bis-NHC rhodium complexes in good yields.
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