Low-coordinate Co(II) and Fe(II) M-terphenyl complex as catalysts for alkyne oligomerization

Resumen del póster presentado a la XXIV Virtual Conference of Organometallic Chemistry (EuCOMC XXIV), celebrada del 1 al 3 de septiembre de 2021.Peer reviewe

Homotropic Cooperativity in Iron-Catalyzed Alkyne Cyclotrimerizations

Enhancing catalytic activity through synergic effects is a current challenge in homogeneous catalysis. In addition to the well-established metal–metal and metal–ligand cooperation, we showcase here an example of self-activation by the substrate in controlling the catalytic activity of the two-coordinate iron complex [Fe(2,6-Xyl2C6H3)2] (1, Xyl = 2,6-Me2C6H3). This behavior was observed for aryl acetylenes in their regioselective cyclotrimerization to 1,2,4-(aryl)-benzenes. Two kinetically distinct regimes are observed dependent upon the substrate-to-catalyst ratio ([RC≡CH]0/[1]0), referred to as the low ([RC≡CH]0/[1]0 40) regimes. Both showed sigmoidal kinetic response, with positive Hill indices of 1.85 and 3.62, respectively, and nonlinear Lineweaver–Burk replots with an upward curvature, which supports positive substrate cooperativity. Moreover, two alkyne molecules participate in the low regime, whereas up to four are involved in the high regime. The second-order rate dependence on 1 indicates that binuclear complexes are the catalytically competent species in both regimes, with that in the high one being 6 times faster than that involved in the low one. Moreover, Eyring plot analyses revealed two different catalytic cycles, with a rate-determining step more endergonic in the low regime than in the high one, but with a more ordered transition state in the high regime than in the low one

Alkyne cyclotrimerization mediated by low-coordinate Fe(II) and Co(II) complexes

Resumen del trabajo presentado a la 24th Virtual Conference on Organometallic Chemistry (EuCOMC XXIV Virtual Conference), celebrada del 1 al 3 de septiembre de 2021.Peer reviewe

Alkyne cyclotrimerization mediated by two-coordinate Fe(II) and Co(II)m-terphenyl complexes

Trabajo presentado al 1er GEQONOVEL, Simposio de Investigadores Jóvenes del Grupo Especializado de Química Organometálica celebrado de forma virtual el 25 de marzo de 2021.Peer reviewe

Mechanistic insights on the functionalization of CO2 with amines and hydrosilanes catalyzed by a zwitterionic iridium carboxylate-functionalized bis-NHC catalyst

The zwitterionic complex [Cp*IrCl{(MeIm)CHCOO}] (1) efficiently catalyzes the selective hydrosilylation of CO to afford the corresponding silylformate. The best reaction performance has been achieved in acetonitrile at 348 K using HSiMePh. The 1-catalyzed reaction of pyrrolidine with CO and HSiMePh strongly depends on the CO pressure. At low concentration of CO (1 bar) formation of the corresponding silylcarbamate, by insertion of CO into the Si−N bond of the in situ generated silylamine was observed, while at higher pressure (3 bar) the formamide derivative was obtained as major reaction product. The unexpected formation of pyrrolidin-1-ium formate as intermediate of the reaction the 1-catalyzed of CO with pyrrolidine and HSiMePh has been observed, and its role in the formation of 1-formylpyrrolidine rationalized. Moreover, a mechanism for the reaction of CO with hydrosilanes, in the presence and in the absence of amines, based on theoretical calculations has been proposed.The authors express their appreciation for the financial support from MICINN/FEDER projects PGC2018‐099383‐B‐100 and CTQ2016‐75884‐P, and the Regional Government of Aragón/FEDER 2014‐2020 “Building Europe from Aragón” (group E42_17R). J.M. acknowledges the financial support provided by the Spanish “Ministerio de Ciencia, Innovación y Universidades” (FPU14/06003). In addition, the resources from the supercomputer “Memento”, technical expertise and assistance provided by BIFIZCAM (Universidad de Zaragoza) are acknowledged.Peer reviewe

Mechanistic Insights on the Functionalization of CO 2

The zwitterionic complex [Cp*IrCl{(MeIm)CHCOO}] (1) efficiently catalyzes the selective hydrosilylation of CO to afford the corresponding silylformate. The best reaction performance has been achieved in acetonitrile at 348 K using HSiMePh. The 1-catalyzed reaction of pyrrolidine with CO and HSiMePh strongly depends on the CO pressure. At low concentration of CO (1 bar) formation of the corresponding silylcarbamate, by insertion of CO into the Si−N bond of the in situ generated silylamine was observed, while at higher pressure (3 bar) the formamide derivative was obtained as major reaction product. The unexpected formation of pyrrolidin-1-ium formate as intermediate of the reaction the 1-catalyzed of CO with pyrrolidine and HSiMePh has been observed, and its role in the formation of 1-formylpyrrolidine rationalized. Moreover, a mechanism for the reaction of CO with hydrosilanes, in the presence and in the absence of amines, based on theoretical calculations has been proposed.The authors express their appreciation for the financial support from MICINN/FEDER projects PGC2018‐099383‐B‐100 and CTQ2016‐75884‐P, and the Regional Government of Aragón/FEDER 2014‐2020 “Building Europe from Aragón” (group E42_17R). J.M. acknowledges the financial support provided by the Spanish “Ministerio de Ciencia, Innovación y Universidades” (FPU14/06003). In addition, the resources from the supercomputer “Memento”, technical expertise and assistance provided by BIFIZCAM (Universidad de Zaragoza) are acknowledged.Peer reviewe