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Electronic Structure and Reactivity of Metal Carbenes

“…But the mechanistic discussion is still going on. Chen et al conducted electrospray ionization tandem mass spectroscopy investigations [160][161][162][163] and concluded that the metallacyclobutane is a transition state rather than an intermediate, while calculations by Bottoni et al found it to be an intermediate [164]. Additionally several other reaction pathways and intermediates have been proposed [118,[165][166][167][168][169][170], but there is still the need to collect additional data before a definitive answer on the mechanism of olefin metathesis catalysed by Grubbs/Herrmann catalysts can be given.…”

Ruthenium‐based metathesis initiators: Development and use in ring‐opening metathesis polymerization

“…15). 218–220 Amoroso and Fogg reported ROMPs of NBE employing a variety of complexes having the generalized formula RuCl 2 (PP)(PPh) 3 [where PP is a chelated bisphosphine ligand, e.g., 1,4‐bis(diphenylphosphino)butane (dppb)] or [RuCl 2 (dppb)] 2 in combination with phenyldiazomethane 221. Leitner et al performed metathesis polymerizations using 39 with n = 1–3 and proposed a mechanism for the formation of the propagating species with this Ru bisallyl compound 222.…”

On the ligand properties of the P- versus the N-heterocyclic carbene for a Grubbs catalyst in olefin metathesis

“…In principle, the basic mechanism for the olefin metathesis was predicted some time ago by Hérisson and Chauvin [15]. The details of the mechanism are now well substantiated by an intense effort of experimental [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] studies. We may note here that very effective ruthenium carbene catalysts have also been presented in cationic [25] and other systems [26][27][28][29].…”