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Accepted Article Title: Reversing Conventional Reactivity of Mixed Oxo/Alkyl Rare Earth Complexes: Non-Redox Oxygen Atom Transfer Authors: Xigeng Zhou, Jianquan Hong, Haiwen Tian, Lixin Zhang, Linhong Weng, Iker del Rosal, and Laurent Maron This manuscript has been accepted after peer review and appears as an Accepted Article online prior to editing, proofing, and formal publication of the final Version of Record (VoR). This work is currently citable by using the Digital Object Identifier (DOI) given below. The VoR will be published online in Early View as soon as possible and may be different to this Accepted Article as a result of editing. Readers should obtain the VoR from the journal website shown below when it is published to ensure accuracy of information. The authors are responsible for the content of this Accepted Article. To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201711305 Angew. Chem. 10.1002/ange.201711305 Link to VoR: http://dx.doi.org/10.1002/anie.201711305 http://dx.doi.org/10.1002/ange.201711305

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COMMUNICATION Reversing Conventional Reactivity of Mixed Oxo/Alkyl Rare Earth Complexes: Non-Redox Oxygen Atom Transfer

Abstract: The preferential substitution of oxo ligands over alkyl ones of rare earth complexes is commonly considered as “impossible” due to the high oxophilicity of metal centers. Now, it has been shown that simply assembling mixed methyl/oxo rare earth complexes to a rigid trinuclear cluster framework can not only enhance the activity of the Ln-oxo bond, but also protect the highly reactive Ln-alkyl bond, thus providing a previously unrecognized opportunity to selectively manipulate the oxo ligand in the presence of numerous reactive functionalities. Such trimetallic cluster has proved to be a suitable platform for developing the unprecedented non-redox rare earthmediated oxygen atom transfer from ketones to CS2 and PhNCS. Controlled experiments and computational studies shed light on the driving force for these reactions, emphasizing the importance of the sterical accessibility and multimetallic effect of the cluster framework in promoting reversal of reactivity of rare earth oxo complexes.

oxygen sources. However, it remains doubtful whether these oxo complexes can become the oxygen-donating reagents. This is mainly due to a wide range of factors, including the great thermody-namic and kinetic disadvantages and the competitive reactions of traditionally more reactive Ln-alkyl (hydride, amido, etc.) bonds (Scheme 1B). Only a limited number of rare earth oxo complexes bearing strongly coordinated multidentate carbon-, nitrogen- and oxygen-based ancillary ligands are currently known to undergo the oxo protonation and additions across organic and inorganic anhydrides.[11,15,16] Therefore, the discovery of strategies that enhance the reactivity of the lanthanide-oxo motifs is highly desirable. In particular, if the classical preferential reactivity of the highly reactive Ln-alkyl bond over the least reactive Ln-oxo bond could be reversed, it would enhance the utility of rare earth oxo complexes as reagents and catalysts in synthetic chemistry.

Oxygen atom transfer (OAT) reactions are one of the most important reactions in synthetic and biological chemistry. [1-5] Traditionally, metal-mediated OAT reactions are predominantly carried out in two sequential steps, namely, oxidativeoxygenation of low valent metal species followed by reductivedeoxygenation of high valent metal oxo species. Alternatively, the metal-mediated OAT reactions can also be driven by the oxidation/reduction of ligands (Scheme 1A). [5] In both cases the oxygen donor is reduced and the oxygen acceptor is oxidized. The development of non-redox metal-mediated OAT reactions lags far behind, despite its fundamental importance and potential to access different oxygen donors and oxygen acceptors. [6] This is mainly due to the lack of complexes suitable for the sequential non-redox incorporation and liberation of oxo ligands. There still exists a need to establish the factors that govern the stability and reactivity of the metal-oxo moiety. The multimetallic cooperative OAT processes, which represent more accurate models of enzyme’s active sites, have not been explored systematically. [7] Organometallic complexes of rare earth metals are easily transformed into derivatives containing oxo ligands by hydrolysis,[8] oxygenation[9] or metathesis reactions with oxygencontaining species,[10-14] which exhibit fascinating variation in Scheme 1. Scaffold-enabled reactivity reversal of mixed alkyl/oxo rare earth metal complexes. [a]

[b]

[c]

Dr. J. Hong, Ms. H. Tian, Associate Prof. L. Zhang, Prof. X. Zhou, Prof. L. Weng Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University, Shanghai 200433, People's Republic of China E-mail: [email protected], [email protected] Prof. X. Zhou State Key Laboratory of Organometallic Chemistry, Shanghai 200032, People's Republic of China Dr. I. del Rosal, Prof. L. Maron LPCNO, Université de Toulouse, 31077 Toulouse, France [email protected] Supporting information for this article is given via a link at the end of the document.

On the other hand, the Ln-oxo motifs are also related to heterogeneous mixed-metal oxide catalysts. It often remains there some uncertainty on the actual function of rare earth metals, as the metal-containing intermediates are not easily identified in situ.[17] Clearly, a better understanding of the structure–reactivity relationships of the Ln-oxo moieties may provide new clues for explanations of the roles of rare earth additives in heterogeneous catalytic oxygenation and deoxygenation processes, thus benefiting the design of related catalytic systems.

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Jianquan Hong,[a] Haiwen Tian,[a] Lixin Zhang,*[a] Xigeng Zhou,*[a, b] Iker del Rosal,[c] Linhong Weng,[a] and Laurent Maron*[c]

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COMMUNICATION for 4-Y (1.57 ppm for 4-Lu), and the µ2-CH3 proton changing from 0.53 (2-Y) to 0.88 ppm (4-Y) (for 2-Lu vs 4-Lu: 0.96 to 1.30 ppm).[12d] X-ray single crystal diffraction analyses of 2-Dy and 4Dy (Figures S1 and S3 in SI) clearly demonstrate that the oxo ligand is replaced by one sulfur atom. The average Dy-Dy distance of 3.381(1) Å in 4-Dy is significantly longer than the corresponding value (3.277(9) Å) of 2-Dy.

Figure 1. ORTEP diagrams (30% thermal ellipsoids) of 3-Y. The isopropyl groups on benzene ring and all the H atoms are omitted for clarity. Selected bond lengths (Å)): Y1-O1 2.359(4), Y2-O1 2.718(4), Y3-O1 2.370(4), Y1-N7 2.354(5), Y3-S1 2.714(2), O1-C5 1.369(7), S1-C5 1.701(6), N7-C5 1.326(7).

Scheme 3. Selective oxygen ligand transfer from mixed methyl/oxo rare earth complexes to CS2.

Scheme 2. Rare earth metal-mediated OAT from cyclohexanone to PhNCS.

The X-ray structural data and NMR spectroscopy of 3-Y support that the newly formed thiocarbamate dianion acts as a pentadentate bridge to connect the three Y units in a 3-1:2:2bonding mode, indicating that the two negative charges are delocalized on the OC(NPh)S unit (Figure 1). The 1H NMR spectra show that replacement of the oxo ligand by a sulfide group leads to a remarkable signal shift of µ3-CH3 proton from 0.37 ppm for 2-Y (0.66 ppm for 2-Lu) to 1.21 ppm

In order to generalize complexes 2 to act as oxygen-donating reagents, the reaction of 2 with CS2 was further examined. Treatment of 2-Y, 2-Lu and 2-Dy with 0.5 equiv of CS2 at ambient temperature allowed a selective substitution of the oxo ligand by a sulfide, yielding the corresponding sulfide complexes 4 in good yields (Scheme 3). The released CO2 was characterized in situ by GC analysis and 13C{1H} NMR (130.7 ppm). Alike PhNCS, the formation of 4 is also independent on the amount of CS2 used. However, when 2-Sc was used, no reaction took place even at 70 oC. Presumably, this might be attributed to the increased sterically crowding caused by the lanthanide contraction effect, which would prevent CS2 from approaching the nucleophilic oxo ligand, as verified by the least non-bonding distances between different ligands (vide infra).[12d] Alternatively, 4 could also be obtained by a one-pot synthesis directly from 1. For example, treatment of 1-Lu with one equivalent of cyclohexanone in toluene followed by reacting with PhNCS or CS2 at room temperature afforded 4-Lu in good yields.

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We now present a simple way to weaken the Ln-O bond and passivate the highly reactive Ln-C bond. By assembling mixed methyl/oxo rare earth complexes to a rigid trinuclear cluster framework, we are not only able to selectively manipulate the lanthanide-oxo bond in the presence of numerous reactive functional groups, but we can also established a non-redox pathway for the development of new OAT reactions (Scheme 1C). This overcomes the general belief that the Ln–alkyl bonds are more reactive than the Ln-oxo ones and represents an important breakthrough in organometallic chemistry. L13Ln3(µ2-CH3)3(µ3-CH3)(µ3-O) [L1 = PhC(NC6H4iPr2-2,6)2, Ln = Sc(2-Sc), Y(2-Y), Lu(2-Lu), Dy(2-Dy)] were prepared according to our previously reported method.[12d] Interestingly, 2-Y, 2-Lu and 2-Dy exhibit an unusual high activity and selectivity for the oxo ligand exchange. Treatment of 2-Y with excess PhNCS at room temperature gave the addition product 3-Y in 85% yield, while reaction of 2-Lu and 2-Dy with PhNCS under the same conditions afforded the unexpected 4-Lu and 4-Dy, respectively. Heating 3-Y in benzene at 70 oC yielded 4-Y in 91% yield together with the release of PhNCO that was determined by GCMS analysis (Scheme 2). The reaction represents the first example of rare earth-mediated transformation of isothiocyanate to isocyanate. It is well-known that PhNCS[18] and PhNCO[19] readily insert into a Ln-C(N) bond, surprisingly, the Ln-methyl bonds in complexes 2 - 4 remain inert in the presence of excess PhNCS and the resulting PhNCO.

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Reaction of 2 with excess RN=C=NR in toluene afforded only the Ln-O bond addition products (Scheme 4). The formation of 5 and 6 represents the first examples of the structurally identified addition of metal oxide to carbodiimides. In the 1H NMR spectra of 5-Y and 5-Lu, a singlet at 0.72 ppm for 5-Y (1.18 ppm for 5Lu) with integrating to twelve protons suggests the presence of four equivalent µ2-Me units. The two sets of signals for methine protons of isopropyl substituents (δ 3.70 and 3.40 ppm for 5-Y; 3.67 and 3.40 ppm for 5-Lu) accord with the observation that the metal ions in 5-Y and 5-Lu have two different coordination environments in their authentic solid structures (Figures S4 and S5). 6-Y displays similar characteristics in the 1H NMR spectrum. 6-Y (Figure S6) and 6-Dy (Figure S7) are structurally characterized too.

Scheme 4. Selective addition of carbodiimides to the Ln-Oxo bond of 2.

Activation of CS2 is of great interest owing to its fundamental importance[20] and implication in catalytic degradation of CS2 pollutant.[21] However, only one report of the cleavage of both CS bonds of CS2 under ambient conditions appeared recently. [22] The heterogeneous transformation of rare earth oxides to corresponding sesquisulfides requires the use of flowing CS2 at high temperatures (>1000 oC).[23] To explain the unusual reactivity of 2 toward CS2, PhNCS and PhN=C=NPh, the reactions were further investigated by theoretical calculations at the DFT level. Although the theoretical investigation of the reactivity of rare earth complexes is well-developed due to the pioneer work of Maron and Eisenstein, [24] calculations on the reactivity of the multilanthanide complexes are really scarce in the literature as they still remain a challenge for computational methods.[13b,25] The reaction profiles were determined for the reaction of 2 with CS2 (Figure 2). The reaction of 2-Y with CS2 begins by an isomerization of 2-Y where the oxo ligand remains μ3 but in a T-shape environment rather than a trigonal one (2-Y’). This isomerization not only generates free space for the incoming CS2 molecule, but more importantly changes the orientation of the lone pair on O that is now pointing in the direction of the empty fourth position of a square-planar structure. This isomer is therefore the reactive form of the trimer and its formation is favored by the flexibility/steric of the ancillary ligand. From this isomer, it is noteworthy that there is no CS2 adduct formation prior to its insertion;[26] only a long range adduct (ACS2) was found (+0.6 kcal/mol). The system is evolving through the transition state of CS2 addition into the metal-oxo bond (TSACS2BCS2). The barrier is 32.5 kcal/mol from the reactive isomer (39.3 kcal/mol from the entrance channel) in line with a reaction that takes 24 h at room temperature. At the TS, the CS 2

molecule is bonded to two metal centers and is bent in order to allow the interaction between the π* of CS2 and the lone pair of the oxo ligand. The coordination together with the bending of the molecule explains the height of the barrier. The O-C bond is not yet formed (2.16 Å) but there is already an interaction found at the second order donor-acceptor NBO analysis. From the TS, the system yields to a dithiocarbonate complex (BCS2) that is 3.7 kal/mol more stable than the reactive isomer 2-Y’. The obtained dithiocarbonate is μ3-1:η2:η2-bonded with the Y-O-Y angle close to 180° so that the complex could be described as a CS 2 adduct to the oxo complex. Quite unexpectedly, this dithiocarbonate complex can isomerize in order to exchange the position of the oxo and the sulfide, through an accessible transition state (TSBCS2CCS2) with an energy barrier of 28.0 kcal/mol. This leads to a slightly more stable dithiocarbonate (CCS2) isomer (0.7 kcal/mol) where the Y-S-Y angle is close to 180°, that is a kind of COS adduct to the sulfide complex. Finally, from this dithiocarbonate isomer, an easy C-S bond breaking can occur through a low lying transition state (TSCCS2DCS2) with an associated energy barrier of 20.6 kcal/mol. At the TS, the C-S bond is already broken (2.43 Å) and the Y-S-Y angle is acute (132°) with the lone pairs of the sulfur pointing in the opposite direction of the third yttrium. Following the intrinsic reaction coordinate, it leads to the formation of an unstable COS adduct (DCS2 +14.6 kcal/mol), where the COS molecule interacts with only one yttrium atom and the sulfide ligand remains bonded to two metals. Therefore, the system expels the COS molecule, yielding the stable 4-Y (-3.2 kcal/mol). This quite unexpected replacement can be explained by NBO analysis. Indeed, the softer sulfide allows a better overlap with the cluster Y3 core orbitals than the harder oxo, indicating the crucial influence of the chosen framework. To summarize, the rate determining step of the reaction is the CS2 addition, yielding to the formation of 4-Y that is 3.2 kcal/mol more stable than 2-Y. Since experimentally only CO2 is detected as a product of the reaction, the reactivity of the formed COS with 2-Y was also investigated. The computed reaction mechanism is very similar to the one described with CS2. It should be noticed that the reaction of 2-Y with COS is kinetically equivalent to the reaction of 2-Y with CS2 (highest barrier of 32 kcal/mol) as well as the COS insertion into the Y-O-Y bond in 2-Y is equivalent to the COS insertion into the Y-S-Y bond in 4-Y (26.0 kcal/mol vs. 26.2 kcal/mol). This is in line with the fact that the reaction requires 24 h at RT. Interestingly, the formation of the monothiocarbonate is roughly 10.3 kcal/mol more favorable than the dithiocarbonate one, making the isomerization of the former the rate determining step of the reaction of COS. The computational studies support the idea that the sterics of the coligand is crucial to allow the isomerization of complex 2-Y from trigonal to T-shape for the CS2/COS insertion. Electronic effects as well as product stability play a key role in determining the preferred transformations of the oxo ligand of such complexes as the atomic orbitals of the softer sulfide overlap better with the cluster Y 3 core ones than the harder oxo as apparent in the bonding Y3-X orbital (see Figure S24), justifying the ingenious choice of the framework. The calculations on the reactivity of PhNCS and carbodiimide with 2-Y lead to similar results as the one described above (see profile in Figure S25), generalizing the reactivity.

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Figure 2. Computed reaction profile at R.T. for the reactivity of oxo-transfer reaction on 2-Y with CS2.

In heterogeneous catalysis, di- and multimetallic coordinations are less in favor of the release of oxygen and CO2 moieties from rare earth centers compared to their monodentate counterparts.[27] To validate our proposal of the importance of the steric effects on the Ln-O activity over the Ln-Me ones, the amidinate ligand was modified by replacing a phenyl substituent by the bulky 2-dimethylaminobenzyl group. Interestingly, the same reactivity trend was observed when 8-Lu reacted with an excess of CS2 or PhNCS, giving the oxo exchange product 9-Lu in high yields (Scheme 5). Noticeably, the increase of steric congestion for 8-Lu compared with 2-Lu leads to the change of coordination mode of one Me ligand from µ3- to µ2 (Figure S8),[12d] whereas the replacement of the oxo ligand by a sulfide promotes the back-shift of the Me ligand from µ2- to 3 due to the decrease of the tension of the trinuclear rigid frame (Figure S9). This is consistent with observations in the computational part of this study. In contrast with 2-Lu, 8-Lu remains inert in presence of the bulky iPrN=C=NiPr even with prolonged heating at 70 oC (Scheme 5). These results unambiguously show that an increase of the steric congestion of the cluster prevents the accessibility of larger substrates to the oxo ligand. In order to better understand the reason why addition to the Ln-oxo bond can overcome the Ln-methyl one, the least nonbonding distance between different ligands as the primary measure of steric crowding was examined (Table S5). Interestingly, the role of the least non-bonding distances involving the oxo ligand is consistent with the reactivity change of these compounds. For example, 2-Sc with shortest nonbonding distances between different ligands is inert to CS 2 and PhNCS. It is also clear that both the larger steric congestion

around the Me ligands and the shielding of the C-H bond on its nucleophilic carbon play key roles in protecting the Ln-Me bond.

Scheme 5. Production of 8-Lu from cyclohexanone and its conversion to corresponding sulfide cluster.

In summary, rare earth complexes, for the first time, are found to undergo the preferred abstraction and functionalization of oxo ligand over alkyl ones. This offers an opportunity to integrate a platform for developing the non-redox metal-mediated OAT reactions from ketones to CS2 and organic substrates. These results demonstrate that the ingenious design of the architecture and choice of ancillary ligands is an efficient tool for reversing the reactivity of mixed alkyl/oxo rare earth complexes. Obviously, these findings might not only give valuable

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information in utilization of rare earth oxo complexes as oxygen donors, but also offer hope in the search for the methods for the regeneration/deoxygenation of deactivated rare earth catalysts caused by oxygen poisoning. Further studies aimed at understanding the factors that govern the versatility and special qualities of rare earth oxo complexes are currently under active investigation in our laboratory and will be reported in due course.

[9]

[10] [11]

Experimental Section See the Supporting Information for full synthetic, spectroscopic, and structural and computational details. CCDC 1566605 (2-Dy), 1587079 (3-Y), 1566606 (4-Dy), 1587078 (5-Y), 1587077 (5-Lu) 1566608 (6-Y), 1566610 (6-Dy), 1566604 (8-Lu), 1566607 (9-Lu) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

[12]

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Acknowledgements ((optional)) [14]

This research was supported by the National Natural Science Foundation of China (grant nos 21372047, 21672038, 21572034, 21732007) and 973 program (2015CB856600). We also thank Prof. Huadong Wang for helpful discussion.

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Keywords: rare earth complexes • oxygen atom transfer • synthesis • reaction • theoretical calculation [16] [1]

[2]

[3]

[4]

[5]

[6]

[7] [8]

a) R. H. Holm, Chem. Rev. 1987, 87, 1401-1449; b) M. M. Abu-Omar, A. Loaiza, N. Hontzeas, Chem. Rev. 2005, 105, 2227-2252; c) S. C. A. Sousa, A. C. Fernandes, Coord. Chem. Rev. 2015, 284, 67-92; d) Z. Q. Chen, G. C. Yin, Chem. Soc. Rev. 2015, 44, 1083-1100. T. Hartmann, P. Schrapers, T. Utesch, M. Nimtz, Y. Rippers, H. Dau, M. A. Mroginski, M. Haumann, S. Leimkühler, Biochemistry 2016, 55, 2381-2389. a) H. M. Neu, R. A. Baglia, D. P. Goldberg, Acc. Chem. Res. 2015, 48, 2754-2764; b) J. Serrano-Plana, I. Garcia-Bosch, A. Company, M. Costas, Acc. Chem. Res. 2015, 48, 2397-2406. a) E. Poverenov, I. Efremenko, A. I. Frenkel, Y. Ben-David, L. J. W. Shimon, G. Leitus, L. Konstantinovski, J. M. L. Martin, D. Milstein, Nature, 2008, 455, 1093-1096; b) J. M. Hoffman, A. G. Oliver, S. N. Brown, J. Am. Chem. Soc. 2017, 139, 4521-4531. a) R. Guilard, M. Fontesse, P. Fournari, C. Lecomte, J. Protas, J. Chem. Soc., Chem. Commun. 1976, 161-162; b) A. H. Randolph, N. J. Seewald, K. Rickert, S. N. Brown, Inorg. Chem. 2013, 52, 12587-12598. a) S. C. Bart, C. Anthon, F. W. Heinemann, E. Bill, N. M. Edelstein, K. Meyer, J. Am. Chem. Soc. 2008, 130, 12536-12546; b) W. Ren, G. Zi, D.-C. Fang, M. D. Walter, J. Am. Chem. Soc. 2011, 133, 13183-13196; c) B. Zhou, Z. Q. Chen, Y. X. Yang, W. Ai, H. Y. Tang, Y. X. Wu, W. L. Zhu, Y. C. Li, Angew. Chem. 2015, 127, 12289-12294; Angew. Chem. Int. Ed. 2015, 54, 12121-12126; d) C. V. S. Kumar, C. V. Ramana, Org. Lett. 2015, 17, 2870-2873; e) R. P. Kelly, M. Falcone, C. A. Lamsfus, R. Scopelliti, L. Maron, K. Meyerc, M. Mazzanti, Chem. Sci. 2017, 8, 53195328. J. Yano, V. Yachandra, Chem. Rev. 2014, 114, 4175-4205. a) H. Schumann, J. A. Meese-Marktscheffel, L. Esser, Chem. Rev. 1995, 95, 865-986; b) J.-B. Peng, X.-J. Kong, Q.-C. Zhang, M. Orendáč, J. Prokleška, Y.-P. Ren, L.-S. Long, Z. Zheng, L.-S. Zheng, J. Am.

[17]

[18] [19]

[20] [21]

[22] [23] [24] [25] [26] [27]

Chem. Soc. 2014, 136, 17938-17941; c) G. Calvez, F. Le Natur, C. Daiguebonne, K. Bernot, Y. Suffren, O. Guillou, Coord. Chem. Rev. 2017, 340, 134-153. a) W. J. Evans, J. W. Grate, I. Bloom, W. E. Hunter, J. L. Atwood, J. Am. Chem. Soc. 1985, 107, 405-409; b) M. P. Coles, P. B. Hitchcock, A. V. Khvostov, M. F. Lappert, Z. Li, A. V. Protchenko, Dalton Trans. 2010, 39, 6780-6788; c) P. L. Damon, G. Wu, N. Kaltsoyannis, T. W. Hayton, J. Am. Chem. Soc. 2016, 138, 12743-12746. a) T. Shima, Z. M. Hou, J. Am. Chem. Soc. 2006, 128, 8124-8125; b) J. Cheng, M. J. Ferguson, J. Takats, J. Am. Chem. Soc. 2010, 132, 2-3. O. Tardif, D. Hashizume, Z. M. Hou, J. Am. Chem. Soc. 2004, 126, 8080-8081. a) J. Scott, H. Fan, B. F. Wicker, A. R. Fout, M.-H. Baik, D. J. Mindiola, J. Am. Chem. Soc. 2008, 130, 14438-14439; b) M. Fustier, X. F. Le Goff, P. Le Floch, N. Mézailles, J. Am. Chem. Soc. 2010, 132, 1310813110; c) W.-X. Zhang, Z. Wang, M. Nishiura, Z. Xi, Z. M. Hou, J. Am. Chem. Soc. 2011, 133, 5712-5715; d) J. Q. Hong, L. X. Zhang, X. Y. Yu, M. Li, Z. X. Zhang, P. Z. Zheng, M. Nishiura, Z. M. Hou, X. G. Zhou, Chem. Eur. J. 2011, 17, 2130-2137. a) Y. Lv, C. E. Kefalidis, J. Zhou, L. Maron, X. Leng, Y. Chen, J. Am. Chem. Soc. 2013, 135, 14784-14796; b) K. Wang, G. Luo, J. Q. Hong, X. G. Zhou, L. H. Weng, Y. Luo, L. X. Zhang, Angew. Chem. 2014, 126, 1071-1074; Angew. Chem. Int. Ed. 2014, 53, 1053-1056. a) P. L. Arnold, E. Hollis, F. J. White, N. Magnani, R. Caciuffo, J. B. Love, Angew. Chem. 2011, 123, 917-920; Angew. Chem. Int. Ed. 2011, 50, 887-890; b) J. Hao, J. Li, C. Cui, H. W. Roesky, Inorg. Chem. 2011, 50, 7453-7459. a) Y.-M. So, G.-C. Wang, Y. Li, H. H.-Y. Sung, I. D. Williams, Z. Lin, W.H. Leung, Angew. Chem. 2014, 126, 1652-1655; Angew. Chem. Int. Ed. 2014, 53, 1626-1629; b) G.-C. Wang, Y.-M. So, K.-L. Wong, K.-C. AuYeung, H. H.-Y. Sung, I. D. Williams, W.-H. Leung, Chem. Eur. J. 2015, 21, 16126-16135; c) P. L. Damon, G. Wu, N. Kaltsoyannis, T. W. Hayton, J. Am. Chem. Soc. 2016, 138, 12743-12746. C. Schoo, S. V. Klementyeva, M. T. Gamer, S. N. Konchenkoacd, P. W. Roesky, Chem. Commun. 2016, 52, 6654-6657. a) Z. Ma, S. H. Overbury, S. Dai, J. Mol. Catal. A-Chem. 2007, 273, 186-197; b) M. Haneda, Y. Tomida, H. Sawada, M. Hattori, Top. Catal. 2016, 59, 1059-1064. a) H. Li, Y. Yao, Q. Shen, L. H. Weng, Organometallics 2002, 21, 25292532; b) J. Zhang, X. G. Zhou Dalton Trans. 2011, 40, 9637-9648. a) W. J. Evans, K. J. Forrestal, J. W. Ziller, J. Am. Chem. Soc. 1998, 120, 9273-9282; b) X. G. Zhou, L. B. Zhang, M. Zhu, R. F. Cai, L. H. Weng, Z. X. Huang, Q. J. Wu, Organometallics 2001, 20, 5700-5706; c) L. Mao, Q. Shen, M. Xue, J. Sun, Organometallics 1997, 16, 3711-3714. a) W. Petz, Coord. Chem. Rev. 2008, 252, 1689-1733; b) L. Wang, W. He, Z. Yu, Chem. Soc. Rev. 2013, 42, 599-621. a) N. D. Sze, M. K. W. Ko, Nature 1979, 280, 308-310; b) R. P. Turco, R. C. Whitten, O. B. Toon, J. B. Pollack, P. Hamill, Nature 1980, 283, 283-285; c) R. A. Cox, D. Sheppard, Nature 1980, 284, 330-331; d) A. K. Yadav, L. D. S. Yadav, Green Chem. 2016, 18, 4240-4244. X. F. Jiang, H. Huang, Y.-F. Chai, T. L. Lohr, S.-Y. Yu, W. Z. Lai, Y.-J. Pan, M. Delferro, T. J. Marks, Nat. Chem. 2017, 9, 188-193. M. Ohta, H. Yuan, S. Hirai, Y. Uemura, K. Shimakage, J. Alloy Compd. 2004, 374, 112-115. L. Maron, O. Eisenstein, J. Phys. Chem. A 2000, 104, 7140-7143. G. Luo, Y. Luo, J. P. Qu, Z. M. Hou, Organometallics 2015, 34, 366-372. a) M. R. Gagné, C. L. Stern, T. J. Marks, J. Am. Chem. Soc. 1992, 114, 275-294; b) S. Tobisch, J. Am. Chem. Soc. 2005, 127, 11979-11988. a) J. Ke, J.-W. Xiao, W. Zhu, H. Liu, R. Si, Y.-W. Zhang, C.-H. Yan, J. Am. Chem. Soc. 2013, 135, 15191-15200; b) C. Choe, Z. Lv, Y. F. Wu, Z. Q. Chen, T. T. Sun, H. B. Wang, G. X. Li, G. H. Yin, Mol. Catal. 2017, 438, 230-238.

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10.1002/anie.201711305

Angewandte Chemie International Edition

COMMUNICATION COMMUNICATION Jianquan Hong, Haiwen Tian, Lixin Zhang,* Xigeng Zhou,* Iker del Rosal, Linhong Weng and Laurent Maron*

The preferential substitution and functionalization of oxo ligands over alkyl ones is commonly referred to as “impossible” in lanthanide chemistry due to the high oxophilicity of the metal center. Now, it has been shown that the reactivity of mixed methyl/oxo lanthanide complexes can be switched and controlled. This offers an opportunity to integrate a platform for developing the redox inactive lanthanidemediated oxygen atom transfer under mild conditions.

Reversing Conventional Reactivity of Mixed Oxo/Alkyl Rare Earth Complexes: Non-Redox Oxygen Atom Transfer

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