RT journal article
T1 Counteranion and Solvent Assistance in Ruthenium-Mediated Alkyne to Vinylidene Isomerizations
A1 Jiménez Tenorio, Manuel
A1 Puerta Vizcaino, María del Carmen
A1 Valerga Jiménez, Pedro Sixto
A2 Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
AB The complex [Cp*RuCl(iPr2PNHPy)] (1) reacts with 1-alkynes HC≡CR (R = COOMe, C6H4CF3) indichloromethane furnishing the corresponding vinylidene complexes [Cp*Ru≡C≡CHR(iPr2PNHPy)]Cl (R = COOMe (2a-Cl), C6H4CF3 (2b-Cl)), whereas reaction of 1 with NaBPh4 in MeOH followed by addition of HC≡CR (R = COOMe,C6H4CF3) yields the metastable π-alkyne complexes [Cp*Ru(η2-HC≡CR)(iPr2PNHPy)][BPh4] (R = COOMe (3a-BPh4),C6H4CF3 (3b-BPh4)). The transformation of 3a-BPh4/3b-BPh4 into their respective vinylidene isomers in dichloromethane isvery slow and requires hours to its completion. However, this process is accelerated by addition of LiCl in methanol solution.Reaction of 1 with HC≡CR (R = COOMe, C6H4CF3) in MeOH goes through the intermediacy of the π-alkyne complexes[Cp*Ru(η2-HC≡CR)(iPr2PNHPy)]Cl (R = COOMe (3a-Cl), C6H4CF3 (3b-Cl)), which rearrange to vinylidenes in minutes,i.e., much faster than their counterparts containing the [BPh4]− anion. The kinetics of these isomerizations has been studied insolution by NMR. With the help of DFT studies, these observations have been interpreted in terms of chloride- and methanolassistedhydrogen migrations. Calculations suggest participation of a hydrido−alkynyl intermediate in the process, in which thehydrogen atom can be transferred from the metal to the β-carbon by means of species with weak basic character acting as protonshuttles.
PB ACS Publications
YR 2013
FD 2013-07
LK http://hdl.handle.net/10498/20428
UL http://hdl.handle.net/10498/20428
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 21-sep-2026