No abstract

A tailored hybrid mesostructured material containing regularly distributed imidazolium units, and subsequent transformation of these imidazolium moieties into Ir‐NHC (NHC=N‐heterocyclic carbene) complexes via the formation of Ag‐NHC species in situ and further transmetalation with [{IrCp*Cl2}2], gives a well‐defined, active, and reusable Ir‐NHC heterogeneous catalyst for H/D exchange reactions (see picture).

The monosiloxy surface complexes [([triple bond]SiO)Mo([triple bond]NAr)(=CHCMe(2)R')(OR)] (R' = Me or Ph; OR = OtBu, OCMe(CF(3))(2) or OAr) are obtained by grafting onto SiO(2-(700)) either symmetric Mo-alkylidene derivatives [Mo([triple bond]NAr)(=CHCMe(2)R')(OR)(2)] or asymmetric derivatives, that is, with two different pendant ligands, one amido and one alkoxy/aryloxy, [Mo([triple bond]NAr)(=CHCMe(2)R')(OR)(NC(6)H(8))]. The formation of these complexes was confirmed by mass-balance analysis, and infrared (IR) and NMR spectroscopies. These systems are highly efficient catalyst precursors for the metathesis of acyclic alkenes; the best results were seen when OR=OCMe(CF(3))(2). Nevertheless, they display poor performances in ring-closing metathesis, possibly due to the rigidity of the metal center (as evidenced by NMR spectroscopy), which therefore slows the rate of the metathesis.