Miguel Angel Gaona Fernandez

• Buchaca, Marc Martínez de Sarasa; Fernandez, Miguel Angel Gaona; Sánchez-Barba, Luis F.; Garcés, Andrés; Rodríguez, Ana M. & Rodríguez-Diéguez, Antonio [Vis alle 9 forfattere av denne artikkelen] (2024). Zinc-Catalyzed Cyclization of Alkynyl Derivatives: Substrate Scope and Mechanistic Insights. Inorganic Chemistry. ISSN 0020-1669. 63(30), s. 13875–13885. doi: 10.1021/acs.inorgchem.4c00832. Fulltekst i vitenarkiv Vis sammendrag

  Novel alkyl zinc complexes supported by acetamidate/thioacetamidate heteroscorpionate ligands have been successfully synthesized and characterized. These complexes exhibited different coordination modes depending on the electronic and steric effects of the acetamidate/thioacetamidate moiety. Their catalytic activity has been tested toward the hydroelementation reactions of alkynyl alcohol/acid substrates, affording the corresponding enol ether/unsaturated lactone products under mild reaction conditions. Kinetic studies have been performed and confirmed that reactions are first-order in [catalyst] and zero-order in [alkynyl substrate]. DFT calculations supported a reaction mechanism through the formation of the catalytically active species, an alkoxide-zinc intermediate, by a protonolysis reaction of the Zn–alkyl bond with the alcohol group of the substrate. Based on the experimental and theoretical results, a catalytic cycle has been proposed.

• Alférez, Macarena G.; Moreno, Juan J.; Fernandez, Miguel Angel Gaona; Maya, Celia & Campos, Jesús (2023). Ligand Postsynthetic Functionalization with Fluorinated Boranes and Implications in Hydrogenation Catalysis. ACS Catalysis. 13(24), s. 16055–16066. doi: 10.1021/acscatal.3c02764. Fulltekst i vitenarkiv Vis sammendrag

  The incorporation of boron functionalities into transition-metal catalysts has become a promising strategy to improve catalytic performance, although their synthesis typically entails the preparation of sophisticated bifunctional ligands. We report here the facile and direct postsynthetic functionalization of rhodium(I) compound [(η5-C9H7)Rh(PPh3)2] (1) by treatment with perfluorinated boranes. Borane addition to 1 results in an unusual C(sp2)-H hydride migration from the indenyl ligand to the metal with the concomitant formation of a C–B bond. In the case of Piers’ borane [HB(C6F5)2], this is followed by a subsequent hydride migration that leads to an unprecedented 1,2-hydrogen shift reminiscent of Milstein’s cooperative dearomatization pathways. Computational investigations provide a mechanistic picture for the successive hydride-migration steps, which enriches the non-innocent chemistry of widespread indenyl ligands. Moreover, we demonstrate that the addition of Piers’ borane is highly beneficial for catalysis, increasing catalyst efficiency up to 3 orders of magnitude.

• Babón, Juan C.; Boudreault, Pierre-Luc T.; Esteruelas, Miguel A.; Fernandez, Miguel Angel Gaona; Izquierdo, Susana & Oliván, Montserrat [Vis alle 9 forfattere av denne artikkelen] (2023). Two Synthetic Tools to Deepen the Understanding of the Influence of Stereochemistry on the Properties of Iridium(III) Heteroleptic Emitters. Inorganic Chemistry. ISSN 0020-1669. 62(49), s. 19821–19837. doi: 10.1021/acs.inorgchem.3c03133. Fulltekst i vitenarkiv Vis sammendrag

  Two complementary procedures are presented to prepare cis-pyridyl-iridium(III) emitters of the class [3b+3b+3b′] with two orthometalated ligands of the 2-phenylpyridine type (3b) and a third ligand (3b′). They allowed to obtain four emitters of this class and to compare their properties with those of the trans-pyridyl isomers. The finding starts from IrH5(PiPr3)2, which reacts with 2-(p-tolyl)pyridine to give fac-[Ir{κ2-C,N-[C6MeH3-py]}3] with an almost quantitative yield. Stirring the latter in the appropriate amount of a saturated solution of HCl in toluene results in the cis-pyridyl adduct IrCl{κ2-C,N-[C6MeH3-py]}2{κ1-Cl-[Cl–H-py-C6MeH4]} stabilized with p-tolylpyridinium chloride, which can also be transformed into dimer cis-[Ir(μ-OH){κ2-C,N-[C6MeH3-py]}2]2. Adduct IrCl{κ2-C,N-[C6MeH3-py]}2{κ1-Cl-[Cl–H-py-C6MeH4]} directly generates cis-[Ir{κ2-C,N-[C6MeH3-py]}2{κ2-C,N-[C6H4–Isoqui]}] and cis-[Ir{κ2-C,N-[C6MeH3-py]}2{κ2-C,N-[C6H4-py]}] by transmetalation from Li[2-(isoquinolin-1-yl)-C6H4] and Li[py-2-C6H4]. Dimer cis-[Ir(μ-OH){κ2-C,N-[C6MeH3-py]}2]2 is also a useful starting complex when the precursor molecule of 3b′ has a fairly acidic hydrogen atom, suitable for removal by hydroxide groups. Thus, its reactions with 2-picolinic acid and acetylacetone (Hacac) lead to cis-Ir{κ2-C,N-[C6MeH3-py]}2{κ2-O,N-[OC(O)-py]} and cis-Ir{κ2-C,N-[C6MeH3-py]}2{κ2-O,O-[acac]}. The stereochemistry of the emitter does not significantly influence the emission wavelengths. On the contrary, its efficiency is highly dependent on and associated with the stability of the isomer. The more stable isomer shows a higher quantum yield and color purity.

• Fernandez, Miguel Angel Gaona; Cruz-Martínez, Felipe de la; Caballero, María P.; Francés-Poveda, Enrique; Rodríguez, Ana M. & Rodríguez-Diéguez, Antonio [Vis alle 9 forfattere av denne artikkelen] (2022). Closing the loop in the synthesis of heteroscorpionate-based aluminium helicates: catalytic studies for cyclic carbonate synthesis. Dalton Transactions. ISSN 1477-9226. 51(30), s. 11302–11315. doi: 10.1039/d2dt01645a. Fulltekst i vitenarkiv Vis sammendrag

  Novel polynuclear helical aluminium complexes supported by bulky heteroscorpionate ligands have been developed and characterised. The use of bulkier ligands has allowed the isolation of unprecedented intermediates for the preparation of helical aluminium complexes. The catalytic activity of these aluminium complexes for cyclic carbonates formation has also been investigated under mild reaction conditions. The combination of complex 16 and Bu4NBr catalysed the synthesis of a broad range of monosubstituted cyclic carbonates from their corresponding epoxides and CO2 at 25 °C and one bar of CO2 pressure. This catalyst system also showed good catalytic activity for the preparation of disubstituted cyclic carbonates from internal epoxides and CO2.

• Martínez, Javier; Cruz-Martínez, Felipe de la; Fernandez, Miguel Angel Gaona; Pinilla-Peñalver, Esther; Fernández-Baeza, Juan & Rodríguez, Ana M. [Vis alle 9 forfattere av denne artikkelen] (2019). Influence of the Counterion on the Synthesis of Cyclic Carbonates Catalyzed by Bifunctional Aluminum Complexes. Inorganic Chemistry. ISSN 0020-1669. 58(5), s. 3408–3408. doi: 10.1021/acs.inorgchem.8b03475. Fulltekst i vitenarkiv Vis sammendrag

  New bifunctional aluminum complexes have been prepared with the aim of studying the effect of a counterion on the synthesis of cyclic carbonates from epoxides and carbon dioxide (CO2). Neutral ligand 1 was used as a precursor to obtain four novel mesylate, chloride, bromide, and iodide zwitterionic NNO ligands (2–5). The reaction of these ligands with 1 or 2 equiv of AlR3 (R = Me, Et) allowed the synthesis of mono- and bimetallic bifunctional aluminum complexes [AlR2(κ2-mbpzappe)]X [X = Cl, R = Me (6), Et (7); X = Br, R = Me (8), Et (9); X = I, R = Me (10), Et (11)] and [{AlR2(κ2-mbpzappe)}(μ-O){AlR3}]X [X = MeSO3, R = Me (12), Et (13); X = Cl, R = Me (14), Et (15); X = Br, R = Me (16), Et (17); X = I, R = Me (18), Et (19)] via alkane elimination. These complexes were studied as catalysts for the synthesis of cyclic carbonates from epoxides and CO2. Iodide complex 11 showed to be the most active catalyst for terminal epoxides, whereas bromide complex 9 was found to be the optimal catalyst when internal epoxides were used, showing the importance of the nucleophile cocatalyst on the catalytic activity.

• Cruz-Martínez, Felipe de la; Martínez, Javier; Fernandez, Miguel Angel Gaona; Fernández-Baeza, Juan; Sánchez-Barba, Luis F. & Rodríguez, Ana M. [Vis alle 9 forfattere av denne artikkelen] (2018). Bifunctional Aluminum Catalysts for the Chemical Fixation of Carbon Dioxide into Cyclic Carbonates. ACS Sustainable Chemistry and Engineering. 6(4), s. 5322–5332. doi: 10.1021/acssuschemeng.8b00102. Fulltekst i vitenarkiv Vis sammendrag

  Bifunctional aluminum complexes supported by novel zwitterionic NNO-donor scorpionate ligands were found to be efficient bifunctional catalysts for cyclic carbonate synthesis from terminal and internal epoxides in good yields and with broad substrate scope. Neutral scorpionate ligands (1–2) were designed and used as precursors to obtain two novel zwitterionic NNO-heteroscorpionate ligands (3–4). Reaction of 3 or 4 with [AlX3] (X = Me, Et) in a 1:1 or 1:2 molar ratio afforded the mononuclear and dinuclear cationic aluminum complexes [AlX2{κ2-mbpzbdmape}]I2 (X = Me (5), Et (6)), [AlX2{κ2-mbpzbdeape}]I2 (X = Me (7), Et (8)), [{AlX2(κ2-mbpzbdmape)}(μ-O){AlX3}]I2 (X = Me (9), Et (10)), and [{AlX2(κ2-mbpzbdeape)}(μ-O){AlX3}]I2 (X = Me (11), Et (12)) with elimination of the corresponding alkane. These complexes were investigated as catalysts for cyclic carbonate formation from epoxides and carbon dioxide in the absence of a co-catalyst. Complex 7 was found to be the most active catalyst for cyclic carbonate formation from various epoxides and carbon dioxide.

Se alle arbeider i NVA