Cumulenylidene ligands

Based on the insight that a dissociative mechanism plays the major role along the metathesis pathway [11], these catalysts have been designed such that only one bulky phosphine, one chloride and one cumulenylidene ligand are attached to a Ru(II) center. Because arene ligands are known to be labile on such a metal fragment, they will easily liberate free coordination sites ( ) for the interaction with the alkene substrate. Although the precise mode of action of such allenyli-... 

Both categories of sp-hybridized neutral carbon ligands, namely the all-carbon-substituted and heteroatom-conjugated allenylidene and cumulenylidene ligands, are presented in great detail by V. Cadiemo and S. E. Garcia-Garrido in the sixth and seventh chapters of this volume, respectively. 

All-Carbon-Substituted Allenylidene and Related Cumulenylidene Ligands... 

Keywords Allenylidene ligands Carbene complexes Cumulenylidene ligands Pentatetraenylidene ligands Propargylic alcohols... 

Structural parameters of selected mononuclear complexes containing heteroatomic 7i-donor-substituted allenylidene ligands are summarized in Table 1. When these data are compared to those reported for related complexes bearing conventional alkyl or aryl substituents (see Table 1 of chapter All-Carbon-Substituted Allenylidene and Related Cumulenylidene Ligands ), a lengthening of the M=C bond... 

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