Ruthenium chelating indenylidene ligand

Ruthenium Catalysts Bearing a Chelating Indenylidene Ligand... 

Scheme 14.27 Ruthenium complexes containing a chelating indenylidene ligand.

Indenylidene complexes have also made their mark in ruthenium olefin metathesis complexes. First noticed by Nolan and coworkers [48] and Furstner et al. [49], these complexes were developed by Nolan and coworkers [50,51] to afford the very stable second-generation complexes 14 (with NHC ligands). More recently, Schrodi and coworkers [52] and Bruneau and coworkers [53,54] presented chelated indenylidene complexes 15 and 16 (Figure 11.5). The relatively fecile methodology for their synthesis and their increased stability certainly makes the indenylidene complexes another well-studied family in the rutheniiun olefin metathesis catalyst field. 

Figure 12.11 Ruthenium complexes with S-chelated carbene ligand (46, 47), phosphene chelated carbene ligand (48), and bidentate isopropoxy-indenylidene ligand (49, 50).

Second-Generation Ruthenium Indenylidene Catalysts Bearing a N-Heterocyclic Carbene or a Chelating NHC-Phosphine Ligand... 

The family of ruthenium(NHC)(phosphine) complexes also includes chelating NHC/phosphine ligands. In a recent example by Hofmann [59], a ruthenium-indenylidene complex was prepared in 60% yield from 5 and the free phosphine-carbene ligand 46 in toluene at 80 °C. In this, the chelate forces the carbene and phosphine ligands into a cis position (Scheme 14.20). No evaluation ofthe catalytic activity of complex 47 in olefin metathesis was reported. 

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