Studies of the decomposition of the ethylene hydrophenylation catalyst TpRu(CO)(NCMe)Ph

Ruthenium-catalyzed hydroarylation reactions as the strategy towards the synthesis of alkylated arenes and substituted alkenes

“… 36 Gunnoe et al studied in detail about the effect of concentration of the above catalyst and the ethylene pressure on the decomposition pathways of the catalyst. 37 Studies show that there are two competing catalyst deactivation pathways in Ru catalyzed ethylene hydrophenylation and the dominant or recessive effect of these two pathways are dependent on the reaction conditions. Among the decomposition pathways one is a bimolecular decomposition mode which forms a paramagnetic species which is still uncharacterised and the second mode is an η 3 allyl complex of catalyst formation via ethylene C–H activation ( Scheme 45 ).…”

Supported Electrophilic Organoruthenium Catalyst for the Hydrosilylation of Olefins

“…Only anti-Markovnikov products resulting from syn-insertion are observed. Inspired by these unique results, we envision that supporting Ru organometallic precursors on acidic supports, such as sulfated zirconia, will not only stabilize these catalysts toward decomposition 23,24 but also allow the formation of a cation-like Ru center on the surface, 25 which is needed to yield the metal-silylene active site (Scheme 1b). We have recently reported that the chemisorption of ( dm Phebox)-Ir(OAc) 2 (OH 2 ) ( dm Phebox = 2,6-bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) on sulfated zirconia generates an electrophilic, cation-like iridium center capable of activating C−H bonds at lower temperature than the homogeneous counterpart.…”

“…Only anti-Markovnikov products resulting from syn-insertion are observed. Inspired by these unique results, we envision that supporting Ru organometallic precursors on acidic supports, such as sulfated zirconia, will not only stabilize these catalysts toward decomposition , but also allow the formation of a cation-like Ru center on the surface, which is needed to yield the metal-silylene active site (Scheme b). We have recently reported that the chemisorption of ( dm Phebox)­Ir­(OAc) 2 (OH 2 ) ( dm Phebox = 2,6-bis­(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) on sulfated zirconia generates an electrophilic, cation-like iridium center capable of activating C–H bonds at lower temperature than the homogeneous counterpart. , The enhanced reactivity of highly electrophilic molecular species on acidic oxide surfaces represents a new interface between homogeneous and heterogeneous catalysis, with its own challenges and opportunities. − For example, Marks and co-workers have reported the formation of cationic group IV metal centers stabilized on sulfated zirconia for olefin polymerization and hydrogenations. ,− The catalytic activities of these reactive surface species can considerably exceed their homogeneous analogues in some cases, even with the weakest coordinating counteranions. , While there are several known platinum-based recyclable hydrosilylation systems, − there are only a handful of examples of supported ruthenium complexes for hydrosilylation applications reported in the literature. − Another drawback of ruthenium-based catalysts is their low activity.…”