Enhanced Dihydrogen Activation by Mononuclear Iridium(II) Compounds: A Mechanistic Study

Dihydrogen Activation Enhanced Dihydrogen Activation by Mononuclear Iridium(II) Compounds: A Mechanistic Study Nereida Hidalgo, Juan José Moreno, Inés García-Rubio, and Jesús Campos* Dedicated to Maurice Brookhart on the occasion of his 80th birthday Abstract: The organometallic chemistry of 4d and 5d transition metals has been vastly dominated by closedshell states. The reactivity of their metalloradical species is though remarkable, albeit yet poorly understood and with limited mechanistic investigations available. In this work we report the synthesis and characterization of two mononuclear IrII species, including the first dinitrogen adduct. These compounds activate dihydrogen at a dissimilar rate, in the latter case several orders of magnitude faster than its IrIprecursor. A combined experimental/computational investigation to ascertain the mechanism of this transformation in IrII compounds is reported. Introduction Despite its molecular simplicity, dihydrogen (H2) has captivated chemists for generations. Fundamental, applied, and industrially relevant causes have sustained profound interest and extensive research on its coordination and reactivity.[1] Dihydrogen has been considered the ideal energy carrier,[2] and its efficient complexation and activation is crucial in many areas, including hydrogenation and hydroformylation catalysis, isotopic-labelling reactions or fuel cell applications, among others.[3] Dihydrogen activation at transition metal centres commonly proceeds through oxidative addition. Heterolytic dihydrogen splitting is also possible and characteristic of the broadening area of metal–ligand cooperation.[4] A common feature of most previous developments in the homogeneous reactivity of H2is that they are vastly dominated by diamagnetic species. Contrarily, radical pathways have emerged recently for H2activation by main group elements.[5] However, paramagnetic transition metal complexes that bind and split H2are yet scarce,[6] albeit their investigation acquires great relevance as it provides the foundation for hydrogen-atom transfer (HAT) reactions.[7] The same applies to the microscopic reverse reaction, namely diamagnetic hydride species that evolve H2to produce paramagnetic compounds, for which mechanistic information is very limited.[8] Group IX diamagnetic metal complexes have played a major role in the fundamental developments and catalytic applications of H2.[9] On the contrary, paramagnetic mononuclear complexes of RhII,[10] and particularly IrII,[11] are uncommon, and despite recent advances their reactivity remains underexplored. Seminal work from Wayland and co-workers on H2splitting by bimetalloradical RhII porphyrin systems evidenced that the activation of H2proceeds in an homolytic fashion characterized by near linear four centred transition states of type [RhII···H···H···RhII].[12] Similar homolytic bimetallic pathways were earlier proposed for other metalloradical species.[13] An alternative mechanism was suggested by Reek and van der Vlugt for a mononuclear RhII complex that is reduced to RhIvia an outer-sphere redox process and then followed by protonation.[14] Metalligand cooperation to facilitate heterolytic H2splitting over a RhII site was also suggested by Ozerov,[15] contrasting to a similar RhII system reported by Milstein for which that possibility was absent, thus revealing no activity towards dihydrogen.[16] More recently, Rauchfuss demonstrated that the metalloradical [Rh(pyridine)4(thf)2]2+is an active hydrogen oxidation catalyst, though the H2splitting mechanism was not investigated.[17] Related information on iridium(II) species is even more limited. After the seminal examples by Wayland[18] and Wilkinson and Hursthouse (Figure 1),[19] to the best of our knowledge only one other iridium(II) complex capable of activating dihydrogen has been reported, under rather harsh conditions (12 h at 48 bar H2and [*] Dr. N. Hidalgo, Dr. J. J. Moreno, Dr. J. Campos Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avenida Américo Vespucio 49, 41092 Sevilla (Spain) E-mail: [email protected] Dr. I. García-Rubio Centro Universitario de la Defensa Ctra de Huesca s/n, 50090 Zaragoza (Spain) Dr. I. García-Rubio Department of Condensed Matter Physics, Faculty of Sciences, University of Zaragoza Calle Pedro Cerbuna, 50009 Zaragoza (Spain) © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is noncommercial and no modifications or adaptations are made. Angewandte Chemie Research Articles www.angewandte.org How to cite: Angew. Chem. Int. Ed. 2022, 61, e202206831 International Edition: doi.org/10.1002/anie.202206831 German Edition: doi.org/10.1002/ange.202206831 Angew. Chem. Int. Ed. 2022,61, e202206831 (1 of 7) © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH 15213773, 2022, 35, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/anie.202206831 by Csic Organización Central Om (Oficialia Mayor) (Urici), Wiley Online Library on [03/11/2022]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 70°C).[20] None of those reports are substantiated by mechanistic studies on the activation of dihydrogen. In this contribution, we present kinetic, spectroscopic and computational studies of H2activation at d7IrII centres. For this purpose, we have synthesized two mononuclear paramagnetic IrII complexes, Ir(POCOP)OTf (2) and [Ir- (POCOP)N2]BArF4(3) (Figure 1), via oxidation of their IrI precursor [Ir(POCOP)N2] (1) with silver salts ((POCOP)= C6H3-2,6-(OP(tBu)2)2, OTf=trifluoromethanesulfonate, BArF4=tetrakis[3,5-bis(trifluoromethyl)phenyl]borate). This work offers the first mechanistic investigation of H2splitting at an IrII complex, which differs from previous suggested pathways in other group IX metalloradicals. Results and Discussion The neutral IrII compound [Ir(POCOP)OTf] (2) was synthesized by treatment of the newly prepared [Ir(POCOP)N2] (1) with AgOTf (Scheme 1), which resulted in an instantaneous colour change from orange to green and the appearance of a grey precipitate (Ag); the complex was isolated as a green solid in 93% yield. 2was silent in 31P{1H} NMR spectroscopy,[11e] but a broad signal in the 1HNMR spectrum at 16.3 ppm was indicative of a paramagnetic species in solution. On an attempt to isolate an IrII dinitrogen adduct, we switched to AgBArF4, anticipating that N2coordination would remain in the presence of the weakly coordinating [BArF4]anion.[21] The reaction of 1 with AgBArF4led indeed to a different species (3), as hinted by the brown colour of the reaction mixture. Compound 3 was also 31P{1H} NMR-silent, though a broad resonance at 4.64 ppm, shifted from that of 2, was observed by 1H-NMR. The reaction mixture from which 3was formed was filtered and single crystals were grown from a saturated benzene solution, enabling the crystallographic determination of its molecular structure (Figure 2).[22] To the best of our knowledge, this constitutes the first example of N2 coordination to a mononuclear IrII centre,[23] which duly Figure 1. Previous IrII compounds that split dihydrogen and the ones investigated herein. Scheme 1. Synthesis of iridium(II) complexes. Figure 2. ORTEP diagrams of compound 2(a) and 3(b). Hydrogen atoms and the counteranion in 3are excluded for clarity. Thermal ellipsoids are set at 50% probability. Selected bond lengths [Å] and angles [°]: compound 2: Ir1C1 1.969(3), Ir1P1 2.2932(8), Ir1P2 2.3092(8), Ir1O3 2.160(2); P1-Ir1-P2 160.84(3), C1-Ir1-O3 174.83(12), C1-Ir1-P1 80.56(9), C1-Ir1-P2 80.43(9); compound 3: Ir1C1 1.979(5), Ir1P1 2.3133(14), Ir1P2 2.3160(17), Ir1N1 2.045(6), N1N2 1.061 (11); P1-Ir1-P2 160.26(5), C1-Ir1-N1 179.5(3), Ir1-N1-N2 177.4(12), C1Ir1-P1 80.14(16), C1-Ir1-P2 80.18(16). Angewandte Chemie Research Articles Angew. Chem. Int. Ed. 2022,61, e202206831 (2 of 7) © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH 15213773, 2022, 35, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/anie.202206831 by Csic Organización Central Om (Oficialia Mayor) (Urici), Wiley Online Library on [03/11/2022]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License adds to the underexplored coordination chemistry of IrII. The formulation of complexes 1(Figure S4) and 2(Figure 2) was confirmed by X-ray diffraction studies as well. These structures exhibit a square-planar geometry, but some striking differences emerge upon oxidation of 1towards the metalloradical species. The IrC bond length decreases in the oxidized compounds (1, 2.017(4); 2, 1.991(5); 3, 1.979 (5) Å), as foreseen for a stronger σ-donation to the more electrophilic IrII. However, the IrP bond lengths considerably elongate after oxidation (1, 2.2764(11), 2.2778(11); 2, 2.315(1), 2.295(1); 3, 2.313(1), 2.316(2) Å), an effect that finds precedent in two-coordinate group X complexes and that has been attributed to electrostatic and Pauli repulsion effects rather than to molecular orbital-based reasons.[24] The IrN bond length also elongates in 3(2.045(6) Å) with respect to 1(1.971(4) Å), while the NN bond length decreases, likely due to the reduced back-donation to a π*-orbital of N2from the oxidized IrII centre compared to IrI (dNN =1.094(6), 1; 1.061(11) Å, 3). Compounds 2and 3are one-electron IrII paramagnets with μeff =1.56 and 1.75, respectively, as measured by the Evans method in C6D6(2) and C6H5F (3). Their metalloradical character was further confirmed by EPR spectroscopy that shows a very anisotropic spectrum interpreted as one paramagnetic species with S=1/2 and g-values 3.95, 1.16 and 0.86 in the case of compound 2(Figure S19). A different spectrum is found for compound 3(Figure S20), where two S=1/2 species with slightly different g-values are detected (3.33, 1.92 and 1.55 vs 3.80, 1.85 and 1.50), which we attribute to the equilibrium between dinuclear and mononuclear dinitrogen species, well-known for related diamagnetic complexes.[25] In addition, their electronic structure was interrogated by means of unrestricted Density Functional Theory (DFT) calculations. The spin density plot of complex 3(Figure 3) indicates that the iridium oxidation state in the dinitrogen adduct is +2, while for the more electron-rich complex 2the unpaired electron is delocalized between the metal centre and the phenyl group, suggesting that the formal oxidation state of iridium is somewhat higher than +2. Our next goal was to analyse the behaviour of 2and 3 towards H2. After 7 hours under mild conditions (1 bar H2, 25°C), 2fully converts into the diamagnetic species Ir- (POCOP)(H)OTf (4)[26] (Scheme 2). Compound 4exhibits a characteristic hydridic resonance by 1H-NMR at 42.88 ppm, similar to other IrIII POCOP compounds with a vacant site in trans disposition to the hydride ligand.[27] Its structure was corroborated by X-ray diffraction studies (Figure S5). Oxidation to IrIII provides a slight elongation of all Ir-containing bonds (ca. 0.05 Å each) with respect to the IrII compound 2, while other geometric parameters are comparable to the parent species. As aforesaid, mechanistic understanding on the homolytic splitting of dihydrogen by IrII species is lacking, and very limited information for other late-transition metal metalloradicals exists (see literature references cited above). Several mechanistic scenarios can be envisaged for the reaction between 2and H2(Scheme 3): a) Bimetallic homolytic HH cleavage between 2 equivalents of complex 2;[6,14,13] b) Outer-sphere H2reduction of complex 2to anionic IrIand H+, followed by protonation of the former;[14] c) Formation of a dihydrogen sigma complex and subsequent oxidative addition of the HH bond to form an IrIV Figure 3. Spin density plot of complexes 2(A) and 3(B). H atoms and tert-butyl groups were removed for clarity. Scheme 2. Reactivity of IrII complex 2towards H2. Scheme 3. Mechanistic pathways for hydrogen splitting mediated by 2. 1/2 has been used as a stoichiometric coefficient. Angewandte Chemie Research Articles Angew. Chem. Int. Ed. 2022,61, e202206831 (3 of 7) © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH 15213773, 2022, 35, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/anie.202206831 by Csic Organización Central Om (Oficialia Mayor) (Urici), Wiley Online Library on [03/11/2022]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License dihydride, which could be reduced to an anionic IrIII complex by a second equivalent of H2and evolved into 4 after hydride abstraction or alternatively being involved in a hydrogen atom transfer (HAT) event with another molecule of 2;[7] d) Elimination of HOTf from the former σ-H2adduct to form an IrII hydride,[28] which could reduce one equivalent of 2, forming an ion pair comprised of an IrIII cationic hydride and an IrIanionic triflate complex, readily reacting with HOTf to give two equivalents of the observed product 4. We assessed the viability of these pathways by a combined experimental and computational approach. Monitoring the reaction between 2and dihydrogen by NMR spectroscopy revealed the presence of starting material 2, H2and the final product 4. No intermediates were detected in the reaction mixture even at low temperature (80°C). The rate of disappearance of 2under excess dihydrogen (5 bar) followed pseudo-first-order kinetics (kobs =0.0170 s1;ΔG298¼6 =19.9 kcalmol1), suggesting the reaction is first order on the iridium complex 2(Figure S1). This finding rules out the homolytic bimetallic cleavage pathway (route A in Scheme 3), which is the most commonly invoked route proposed for other metalloradicals,[6,13] in some cases substantiated by secondorder kinetics.[12] It also contrasts with the second-order dependence observed by Goldberg for the microscopic reverse process, that is, reductive elimination of dihydrogen from two molecules of an IrIII hydride to form a dinuclear IrII/IrII complex.[8a] A linear dependence of the observed rate constant kobs against the concentration of H2at different pressures at 25°C indicated also a first-order dependence on H2concentration (Figure S2). Moreover, the rate constant of the reaction between 2and D2evinced a strong inverse kinetic isotope effect (KIE) of 0.56�0.01. This suggests the involvement of a sigma dihydrogen complex in a rapid equilibrium preceding HH bond cleavage (routes C and D in Scheme 3),[29] and rules out the direct outer-sphere reduction of complex 2by H2(route B in Scheme 3),[14] for which a normal KIE would be anticipated. Inverse KIEs for H2 activation reactions remain rare, albeit several examples exist in the literature.[30] We conducted open-shell DFT calculations to gain further mechanistic insight (Figure 4). The formation of an IrII-sigma complex is accessible (12.1 kcalmol1barrier, TS1) and endergonic (5.8 kcalmol1), in agreement with the lack of experimentally observed intermediates for the reaction. The transition state TS2, found at 20.4 kcalmol1, displays the attack of an O atom of the triflate group to the metalbound H2moiety, as suggested in route D of Scheme 3, rendering a four coordinate IrII hydride featuring an interaction with HOTf (Figure S6).[31] Our results indicate that an intermolecular electron transfer between this species and unreacted 2is highly exergonic (19.1 kcalmol1), Figure 4. Free energy profile of the proposed reaction mechanism of complex 2towards H2at the PBE0-D3(BJ)/6-311+G(2d,p)//PBE0-D3(BJ)/631G(d,p) level of theory. Angewandte Chemie Research Articles Angew. Chem. Int. Ed. 2022,61, e202206831 (4 of 7) © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH 15213773, 2022, 35, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/anie.202206831 by Csic Organización Central Om (Oficialia Mayor) (Urici), Wiley Online Library on [03/11/2022]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License yielding an ion pair comprised of an IrIII cationic hydride and an anionic IrItriflate complex. During the geometry optimization of the ion pair with HOTf present, the proton reacts with the anionic unit, rendering a neutral, IrI-HOTf adduct and an OTf anion that binds to the cationic IrIII hydride, forming one equivalent of 4. The independent optimization of the IrI-HOTf adduct likewise evolves to 4 via oxidative addition. To ascertain whether this pathway could explain the experimentally determined inverse KIE, we calculated the KIE for the reaction from the zero-point energy differences (ΔΔZPE) between the reactants, 2+H2, and the HH bond cleavage TS, to find an inverse KIE of 0.26, in fair qualitative agreement with experiment. The KIE stems from the combination of a 0.22 equilibrium isotope effect (EIE) between 2and the H2sigma complex and a 1.15 KIE from the sigma complex to the HH bond cleavage TS (Figure S7). Overall, this pathway is in excellent agreement with experimental observations, both by the overall energy and the observed inverse kinetic isotopic effect. Although the above results are strong support of the mechanism labelled as D in Scheme 3, the aforenamed IrII σH2complex, the formation of an IrIV dihydride is also accessible (9.5 kcalmol1, TS3) but highly reversible (route C in Scheme 3; Figure S8). A productive transition state for the reductive elimination of HOTf, which would connect this path with the previously discussed one, could not be located. Furthermore, because the redox potential of the 2H+/H2pair in C6H6is not known and cannot be modelled by DFT methods, further insight on an IrIV/IrIII H2-mediated outer-sphere reduction could not be gathered, precluding a complete assessment of the viability of such pathway. Nonetheless, the first-order dependence on the concentration of H2seems to disagree with this mechanistic proposal, for which a second-order dependence would be expected. Finally, a mechanism involving hydrogen atom transfer (HAT) was assessed by computing the bond dissociation free energy (BDFE) of the IrH bond in the IrIV dihydride (18.1 kcalmol1) and complex 4(63.7 kcalmol1). Therefore, while hydrogen atom transfer (HAT) from the IrIV dihydride to complex 2is thermochemically accessible, an inner-sphere pathway would present second-order dependence on the concentration of 2, due to HAT being rate-limiting (the calculated barrier for the formation of the dihydride (9.5 kcalmol1) is considerably lower than the experimentally determined free energy of activation (19.9 kcalmol1)). Outer sphere HAT from the dihydride presents a calculated barrier of 26.4 kcalmol1, substantially higher than pathway D. Finally, due to the very low BDFE of the IrH bond in the IrIV dihydride, we considered whether the solvent (C6H6) could act as a HAT mediator, which would be consistent with first-order dependence on iridium. Despite HAT to benzene being thermoneutral (BDFE of the CH bond in the cyclohexadienyl radical (c-C6H7) was calculated to be 17.4 kcalmol1), the lowest-energy transition state for HAT to benzene (TS4, Figure S9) was located above 30 kcalmol1; quantum tunnelling can be ruled out, as under these conditions it would be accompanied by a large KIE,[32] in stark contrast with the inverse KIE determined for this system. Thus, we also discard this mechanism in favour of the one represented in Figure 4, which is consistent with all our experimental observations. We also investigated the reactivity of dihydrogen with the IrII dinitrogen adduct 3(Scheme 4). In this case, a solution of 3undergoes immediate colour change from brown to orange-yellow after H2addition (1 bar, 25°C) and two diamagnetic species were observed by NMR in C6D6. These complexes were unambiguously assigned to the dihydride and tetrahydride species 5and 6, both reported by Brookhart.[33] After 2 hours under H2atmosphere complex 6 was the only discernible species (Scheme 4). The activation of H2by compound 3is considerably more rapid than for the triflate adduct 2. Even at 80°C, consumption of 3was complete in less than 5 minutes, disallowing kinetic experiments alike those carried out for 2. Because the formation of two new IrH bonds in complex 5 is only accompanied by a unitary increase of the Ir oxidation state, it is likely that in this scenario H2acts as an outersphere reductant. We further supported this hypothesis by carrying out the reaction of 3and H2in the presence of a bulky base that does not bind to the complex, trimesitylphosphine. 31P{1H} and 1H-NMR monitoring confirmed the formation of the corresponding phosphonium cation, formally [HP(Mes)3][BArF]. Furthermore, while the reaction of complex 1, the one-electron reduction product of 3, with H2 is sluggish (t1/2 �3.5 h),[34] in the presence of acid becomes immediate. These data suggest that 3, much more electrophilic than 2, could be reduced to IrIby H2, producing protons that would facilitate accessing compounds 5and 6. The high reactivity the complex exhibits, even at very low temperatures, precludes however a definitive refusal of an alternative IrIV/IrIII pathway or a bimetallic homolytic cleavage. Nonetheless, this represents an uncommon example in which bond activation is considerably enhanced in the metalloradical IrII species compared to its reduced IrI precursor.[17] Conclusion In summary, two novel IrII complexes have been prepared and fully characterized, including the first monometallic IrII dinitrogen species. The reactivity of these species towards H2has been studied by means of a combined experimental Scheme 4. Reactivity of complex 3towards H2. Angewandte Chemie Research Articles Angew. Chem. Int. Ed. 2022,61, e202206831 (5 of 7) © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH 15213773, 2022, 35, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/anie.202206831 by Csic Organización Central Om (Oficialia Mayor) (Urici), Wiley Online Library on [03/11/2022]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License and computational approach. While for the IrII triflate complex the reaction rate, reaction orders, and inverse KIE agree with the formation of a sigma complex from which triflate-assisted HH bond cleavage takes place, for the more electrophilic, cationic IrII-dinitrogen complex, H2mediated reduction of the metal centre is proposed, which is likely followed by the acid-catalysed oxidative addition of H2. The activation of dihydrogen by the latter IrII system is remarkably enhanced compared to the conventional IrI counterpart, evincing the prospects for improved catalytic systems based on unconventional metalloradical species. Overall, these findings notably contribute to the substantially underdeveloped mononuclear IrII chemistry, for which fundamental mechanistic understanding is yet very limited. Acquiring that fundamental knowledge will be essential for developing innovative bond activation and catalysis based on metalloradical transition metal complexes. Acknowledgements This work has been supported by the European Research Council (ERC Starting Grant, CoopCat), the Spanish Ministry of Science (Project PID2019-110856GAI00) and by a PhosAgro/UNESCO/IUPAC research grant in green chemistry. The use of computational facilities at the Supercomputing Centre of Galicia (CESGA) is acknowledged. J.J.M. thanks Junta de Andalucía for the postdoctoral program “Personal Investigador Doctor” (ref. DOC_00153). Conflict of Interest The authors declare no conflict of interest. Data Availability Statement The data that support the findings of this study are available in the supplementary material of this article. Keywords: Dihydrogen ·Iridium ·Metalloradical · Paramagnetic Compounds [1] a) P. G. Jessop, R. H. Morris, Coord. Chem. Rev. 1992,121, 155–284; b) D. M. Heinekey, W. J. Oldham, Chem. Rev. 1993, 93, 913–926; c) G. J. Kubas, Chem. Rev. 2007,107, 4152–4205. [2] C. Wang, D. Astruc, Chem. Soc. Rev. 2021,50, 3437–3484. [3] R. H. Crabtree, Chem. Rev. 2016,116, 8750–8769. [4] a) B. Askevold, H. W. Roesky, S. Schneider, ChemCatChem 2012,4, 307–320; b) O. Eisenstein, R. H. Crabtree, New J. Chem. 2013,37, 21–27; c) J. R. Khusnutdinova, D. Milstein, Angew. Chem. Int. Ed. 2015,54, 12236–12273; Angew. Chem. 2015,127, 12406–12445; d) R. H. Morris Acc, Chem. Res. 2015, 48, 1494–1502; e) P. A. 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Manuscript received: May 10, 2022 Accepted manuscript online: June 23, 2022 Version of record online: July 13, 2022 Angewandte Chemie Research Articles Angew. Chem. Int. Ed. 2022,61, e202206831 (7 of 7) © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH 15213773, 2022, 35, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/anie.202206831 by Csic Organización Central Om (Oficialia Mayor) (Urici), Wiley Online Library on [03/11/2022]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License