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Le LN, Joyce JP, Oyala PH, DeBeer S, Agapie T. Highly Activated Terminal Carbon Monoxide Ligand in an Iron-Sulfur Cluster Model of FeMco with Intermediate Local Spin State at Fe. J Am Chem Soc 2024; 146:5045-5050. [PMID: 38358932 PMCID: PMC10910499 DOI: 10.1021/jacs.3c12025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/17/2024]
Abstract
Nitrogenases, the enzymes that convert N2 to NH3, also catalyze the reductive coupling of CO to yield hydrocarbons. CO-coordinated species of nitrogenase clusters have been isolated and used to infer mechanistic information. However, synthetic FeS clusters displaying CO ligands remain rare, which limits benchmarking. Starting from a synthetic cluster that models a cubane portion of the FeMo cofactor (FeMoco), including a bridging carbyne ligand, we report a heterometallic tungsten-iron-sulfur cluster with a single terminal CO coordination in two oxidation states with a high level of CO activation (νCO = 1851 and 1751 cm-1). The local Fe coordination environment (2S, 1C, 1CO) is identical to that in the protein making this system a suitable benchmark. Computational studies find an unusual intermediate spin electronic configuration at the Fe sites promoted by the presence the carbyne ligand. This electronic feature is partly responsible for the high degree of CO activation in the reduced cluster.
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Affiliation(s)
- Linh N.
V. Le
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Justin P. Joyce
- Max
Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Paul H. Oyala
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Serena DeBeer
- Max
Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Theodor Agapie
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
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2
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Brown AC, Suess DLM. An Iron-Sulfur Cluster with a Highly Pyramidalized Three-Coordinate Iron Center and a Negligible Affinity for Dinitrogen. J Am Chem Soc 2023; 145:20088-20096. [PMID: 37656961 PMCID: PMC10824254 DOI: 10.1021/jacs.3c07677] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/03/2023]
Abstract
Attempts to generate open coordination sites for N2 binding at synthetic Fe-S clusters often instead result in cluster oligomerization. Recently, it was shown for Mo-Fe-S clusters that such oligomerization reactions can be prevented through the use of sterically protective supporting ligands, thereby enabling N2 complex formation. Here, this strategy is extended to Fe-only Fe-S clusters. One-electron reduction of (IMes)3Fe4S4Cl (IMes = 1,3-dimesitylimidazol-2-ylidene) forms the transiently stable edge-bridged double cubane (IMes)6Fe8S8, which loses two IMes ligands to form the face-bridged double-cubane, (IMes)4Fe8S8. The finding that the three supporting IMes ligands do not confer sufficient protection to curtail cluster oligomerization prompted the design of a new N-heterocyclic carbene, SIArMe,iPr (1,3-bis(3,5-diisopropyl-2,6-dimethylphenyl)-2-imidazolidinylidene; abbreviated as SIAr), that features bulky groups strategically placed in remote positions. When the reduction of (SIAr)3Fe4S4Cl or [(SIAr)3Fe4S4(THF)]+ is conducted in the presence of SIAr, the formation of (SIAr)4Fe8S8 is indeed suppressed, permitting characterization of the reduced [Fe4S4]0 product. Surprisingly, rather than being an N2 complex, the product is simply (SIAr)3Fe4S4: a cluster with a three-coordinate Fe site that adopts an unusually pyramidalized geometry. Although (SIAr)3Fe4S4 does not coordinate N2 to any appreciable extent under the surveyed conditions, it does bind CO to form (SIAr)3Fe4S4(CO). This finding demonstates that the binding pocket at the unique Fe is not too small for N2; instead, the exceptionally weak affinity for N2 can be attributed to weak Fe-N2 bonding. The differences in the N2 coordination chemistry between sterically protected Mo-Fe-S clusters and Fe-only Fe-S clusters are discussed.
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Affiliation(s)
- Alexandra C Brown
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Daniel L M Suess
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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3
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Skeel BA, Suess DLM. Exploiting Molecular Symmetry to Quantitatively Map the Excited-State Landscape of Iron-Sulfur Clusters. J Am Chem Soc 2023; 145:10376-10395. [PMID: 37125463 DOI: 10.1021/jacs.3c02412] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Cuboidal [Fe4S4] clusters are ubiquitous cofactors in biological redox chemistry. In the [Fe4S4]1+ state, pairwise spin coupling gives rise to six arrangements of the Fe valences ("valence isomers") among the four Fe centers. Because of the magnetic complexity of these systems, it has been challenging to understand how a protein's active site dictates both the arrangement of the valences in the ground state as well as the population of excited-state valence isomers. Here, we show that the ground-state valence isomer landscape can be simplified from a six-level system in an asymmetric protein environment to a two-level system by studying the problem in synthetic [Fe4S4]1+ clusters with solution C3v symmetry. This simplification allows for the energy differences between valence isomers to be quantified (in some cases with a resolution of <0.1 kcal/mol) by simultaneously fitting the VT NMR and solution magnetic moment data. Using this fitting protocol, we map the excited-state landscape for a range of clusters of the form [(SIMes)3Fe4S4-X/L]n, (SIMes = 1,3-dimesityl-imidazol-4,5-dihydro-2-ylidene; n = 0 for anionic, X-type ligands and n = +1 for neutral, L-type ligands) and find that a single ligand substitution can alter the relative ground-state energies of valence isomers by at least 103 cm-1. On this basis, we suggest that one result of "non-canonical" amino acid ligation in Fe-S proteins is the redistribution of the valence electrons in the manifold of thermally populated excited states.
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Affiliation(s)
- Brighton A Skeel
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Daniel L M Suess
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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4
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Brown AC, Suess DLM. Valence Localization in Alkyne and Alkene Adducts of Synthetic [Fe 4S 4] + Clusters. Inorg Chem 2023; 62:1911-1918. [PMID: 35704768 PMCID: PMC9751231 DOI: 10.1021/acs.inorgchem.2c01353] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Reported herein are alkyne and alkene adducts of synthetic [Fe4S4]+ clusters that model intermediates and inhibitor-bound states in enzymes involved in isoprenoid biosynthesis. Treatment of the N-heterocyclic carbene-ligated cluster [(IMes)3Fe4S4(OEt2)][BArF4] (IMes = 1,3-dimesitylimidazol-2-ylidene; [BArF4]- = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) with phenylacetylene (PhCCH) or cis-cyclooctene (COE) results in displacement of the Et2O ligand to yield the corresponding π complexes, [(IMes)3Fe4S4(PhCCH)][BArF4] and [(IMes)3Fe4S4(COE)][BArF4]. EPR spectroscopic analysis demonstrates that both clusters are doublets with giso > 2 and thus are spectroscopically faithful models of the analogous species characterized in the isoprenoid biosynthetic enzymes IspG and IspH. Structural and Mössbauer spectroscopic analysis reveals that both complexes are best described as [Fe4S4]+ clusters in which the unique Fe site engages in modest back-bonding to the π-acidic ligand. Paramagnetic NMR studies show that, even at room temperature, the alkyne/alkene-bound Fe centers harbor minority spin and therefore adopt an Fe2+ valence. We propose that such valence localization could likewise occur in Fe-S enzymes that interact with π-acidic molecules.
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5
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Brown AC, Thompson NB, Suess DLM. Evidence for Low-Valent Electronic Configurations in Iron-Sulfur Clusters. J Am Chem Soc 2022; 144:9066-9073. [PMID: 35575703 DOI: 10.1021/jacs.2c01872] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Although biological iron-sulfur (Fe-S) clusters perform some of the most difficult redox reactions in nature, they are thought to be composed exclusively of Fe2+ and Fe3+ ions, as well as mixed-valent pairs with average oxidation states of Fe2.5+. We herein show that Fe-S clusters formally composed of these valences can access a wider range of electronic configurations─in particular, those featuring low-valent Fe1+ centers. We demonstrate that CO binding to a synthetic [Fe4S4]0 cluster supported by N-heterocyclic carbene ligands induces the generation of Fe1+ centers via intracluster electron transfer, wherein a neighboring pair of Fe2+ sites reduces the CO-bound site to a low-valent Fe1+ state. Similarly, CO binding to an [Fe4S4]+ cluster induces electron delocalization with a neighboring Fe site to form a mixed-valent Fe1.5+Fe2.5+ pair in which the CO-bound site adopts partial low-valent character. These low-valent configurations engender remarkable C-O bond activation without having to traverse highly negative and physiologically inaccessible [Fe4S4]0/[Fe4S4]- redox couples.
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Affiliation(s)
- Alexandra C Brown
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Niklas B Thompson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Daniel L M Suess
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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6
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Lee H, Ahn JM, Oyala PH, Citek C, Yin H, Fu GC, Peters JC. Investigation of the C-N Bond-Forming Step in a Photoinduced, Copper-Catalyzed Enantioconvergent N-Alkylation: Characterization and Application of a Stabilized Organic Radical as a Mechanistic Probe. J Am Chem Soc 2022; 144:4114-4123. [PMID: 35167268 PMCID: PMC9269863 DOI: 10.1021/jacs.1c13151] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Whereas photoinduced, copper-catalyzed couplings of nitrogen nucleophiles with alkyl electrophiles have recently been shown to provide an attractive approach to achieving a variety of enantioselective C-N bond constructions, mechanistic studies of these transformations have lagged the advances in reaction development. Herein we provide mechanistic insight into a previously reported photoinduced, copper-catalyzed enantioconvergent C-N coupling of a carbazole nucleophile with a racemic tertiary α-haloamide electrophile. Building on the isolation of a copper(II) model complex whose EPR parameters serve as a guide, we independently synthesize two key intermediates in the proposed catalytic cycle, a copper(II) metalloradical (L*CuII(carb')2) (L* = a monodentate chiral phosphine ligand; carb' = a carbazolide ligand), as well as a tertiary α-amide organic radical (R·); the generation and characterization of R· was guided by DFT calculations, which suggested that it would be stable to homocoupling. Continuous-wave (CW) and pulse EPR studies, along with corresponding DFT calculations, are among the techniques used to characterize these reactive radicals. We establish that these two radicals do indeed combine to furnish the C-N coupling product in good yield and with significant enantiomeric excess (77% yield, 55% ee), thereby supporting the chemical competence of these proposed intermediates. DFT calculations are consistent with R· initially binding to copper(II) via a dative interaction from the closed-shell carbonyl oxygen atom of the radical, which positions the α-carbon for direct reaction with the copper(II)-bound carbazole N atom, to generate the C-N bond with enantioselectivity, without the formation of an alkylcopper(III) intermediate.
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Affiliation(s)
- Heejun Lee
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Jun Myun Ahn
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Paul H Oyala
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Cooper Citek
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Haolin Yin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Gregory C Fu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Jonas C Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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7
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Abstract
Carbide complexes remain a rare class of molecules. Their paucity does not reflect exceptional instability but is rather due to the generally narrow scope of synthetic procedures for constructing carbide complexes. The preparation of carbide complexes typically revolves around generating LnM-CEx fragments, followed by cleavage of the C-E bonds of the coordinated carbon-based ligands (the alternative being direct C atom transfer). Prime examples involve deoxygenation of carbonyl ligands and deprotonation of methyl ligands, but several other p-block fragments can be cleaved off to afford carbide ligands. This Review outlines synthetic strategies toward terminal carbide complexes, bridging carbide complexes, as well as carbide-carbonyl cluster complexes. It then surveys the reactivity of carbide complexes, covering stoichiometric reactions where the carbide ligands act as C1 reagents, engage in cross-coupling reactions, and enact Fischer-Tropsch-like chemistry; in addition, we discuss carbide complexes in the context of catalysis. Finally, we examine spectroscopic features of carbide complexes, which helps to establish the presence of the carbide functionality and address its electronic structure.
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Affiliation(s)
- Anders Reinholdt
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Jesper Bendix
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
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8
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Deegan MM, Peters JC. Synthesis and functionalization reactivity of Fe-thiocarbonyl and thiocarbyne complexes. Polyhedron 2021; 209. [DOI: 10.1016/j.poly.2021.115461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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9
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Sridharan A, Brown AC, Suess DLM. A Terminal Imido Complex of an Iron-Sulfur Cluster. Angew Chem Int Ed Engl 2021; 60:12802-12806. [PMID: 33772994 DOI: 10.1002/anie.202102603] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Indexed: 11/10/2022]
Abstract
We report the synthesis and characterization of the first terminal imido complex of an Fe-S cluster, (IMes)3 Fe4 S4 =NDipp (2; IMes=1,3-dimesitylimidazol-2-ylidene, Dipp=2,6-diisopropylphenyl), which is generated by oxidative group transfer from DippN3 to the all-ferrous cluster (IMes)3 Fe4 S4 (PPh3 ). This two-electron process is achieved by formal one-electron oxidation of the imido-bound Fe site and one-electron oxidation of two IMes-bound Fe sites. Structural, spectroscopic, and computational studies establish that the Fe-imido site is best described as a high-spin Fe3+ center, which is manifested in its long Fe-N(imido) distance of 1.763(2) Å. Cluster 2 abstracts hydrogen atoms from 1,4-cyclohexadiene to yield the corresponding anilido complex, demonstrating competency for C-H activation.
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Affiliation(s)
- Arun Sridharan
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139, USA
| | - Alexandra C Brown
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139, USA
| | - Daniel L M Suess
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139, USA
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10
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Sridharan A, Brown AC, Suess DLM. A Terminal Imido Complex of an Iron–Sulfur Cluster. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202102603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Arun Sridharan
- Department of Chemistry Massachusetts Institute of Technology 77 Massachusetts Ave Cambridge MA 02139 USA
| | - Alexandra C. Brown
- Department of Chemistry Massachusetts Institute of Technology 77 Massachusetts Ave Cambridge MA 02139 USA
| | - Daniel L. M. Suess
- Department of Chemistry Massachusetts Institute of Technology 77 Massachusetts Ave Cambridge MA 02139 USA
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11
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Wellnitz T, Hering‐Junghans C. Synthesis and Reactivity of Monocyclic Homoleptic Oligophosphanes. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000878] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Tim Wellnitz
- Junior Research Groups Leibniz Institute for Catalysis Rostock (LIKAT Rostock) Albert‐Einstein‐Straße 29a 18059 Rostock Germany
| | - Christian Hering‐Junghans
- Junior Research Groups Leibniz Institute for Catalysis Rostock (LIKAT Rostock) Albert‐Einstein‐Straße 29a 18059 Rostock Germany
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12
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Hillenbrand J, van Gastel M, Bill E, Neese F, Fürstner A. Isolation of a Homoleptic Non-oxo Mo(V) Alkoxide Complex: Synthesis, Structure, and Electronic Properties of Penta- tert-Butoxymolybdenum. J Am Chem Soc 2020; 142:16392-16402. [PMID: 32847348 PMCID: PMC7517713 DOI: 10.1021/jacs.0c07073] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Treatment of [MoCl4(THF)2] with MOtBu (M = Na, Li) does not result in simple metathetic ligand exchange but entails disproportionation with formation of the well-known dinuclear complex [(tBuO)3Mo≡Mo(OtBu)3] and a new paramagnetic compound, [Mo(OtBu)5]. This particular five-coordinate species is the first monomeric, homoleptic, all-oxygen-ligated but non-oxo 4d1 Mo(V) complex known to date; as such, it proves that the dominance of the Mo═O group over (high-valent) molybdenum chemistry can be challenged. [Mo(OtBu)5] was characterized in detail by a combined experimental/computational approach using X-ray diffraction; UV/vis, MCD, IR, EPR, and NMR spectroscopy; and quantum chemistry. The recorded data confirm a Jahn-Teller distortion of the structure, as befitting a d1 species, and show that the complex undergoes Berry pseudorotation. The alkoxide ligands render the disproportionation reaction, leading the formation of [Mo(OtBu)5] to be particularly facile, even though the parent complex [MoCl4(THF)2] itself was also found to be intrinsically unstable; remarkably, this substrate converts into a crystalline material, in which the newly formed Mo(III) and Mo(V) products cohabitate the same unit cell.
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Affiliation(s)
| | | | - Eckhard Bill
- Max-Planck-Institute for Chemical Energy Conversion, 45470 Mülheim/Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
| | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
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13
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Yang L, Shu XP, Fu MY, Wang HY, Zhu QY, Dai J. Molybdenum-titanium oxo-cluster, an efficient electrochemical catalyst for the facile preparation of black titanium dioxide film. Dalton Trans 2020; 49:10516-10522. [PMID: 32691817 DOI: 10.1039/d0dt01959c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Black-TiO2 has become increasingly interesting as a promising photoactive material. Most of the preparations for black-TiO2 involve either high temperature calcination, plasma, lengthy chemical reactions or dealing with dangerous or toxic chemicals. We found, by accident, that Mo-Ti oxo-clusters are efficient catalysts for the hydrogenation of a TiO2 electrode to black-TiO2 at room temperature. A series of Mo-Ti oxo-clusters, [Ti4Mo4O10(OR)14(X-BA)2] (BA = benzoate, X = H (1), F (2), Cl (3), and Br (4)), were prepared and were characterized by crystallography. They have a Mo4Ti4 structure with Mo(v)-Mo(v) metal-metal interactions. The activated hydrogen (H*) generated by electrochemically catalytic water splitting turns the TiO2 electrode to black-TiO2 at room temperature, due to the reduction of Ti(iv) to H+Ti(iii). The potentials applied for water reduction must generally be higher than the overpotential at the TiO2 electrode (-1.0 V vs. RHE). In this work, the onset potential of hydrogen evolution significantly decreased to -0.1 V vs. RHE. Using this blackened 1-TiO2 electrode, the effective electrochemical catalytic degradation of a dye was examined in comparison with the degradation using the white TiO2 electrode. This work provides a method for the facile preparation of a black-TiO2 film, and is a step forward in black-TiO2 research.
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Affiliation(s)
- Lei Yang
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China.
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14
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Boucher-Jacobs C, Liu P, Nicholas KM. Mechanistic Insights into the ReIO2(PPh3)2-Promoted Reductive Coupling of Alcohols. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00285] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Camille Boucher-Jacobs
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Kenneth M. Nicholas
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
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15
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Paparo A, van Krüchten FD, Spaniol TP, Okuda J. Formate complexes of titanium(iv) supported by a triamido-amine ligand. Dalton Trans 2018; 47:3530-3537. [PMID: 29431800 DOI: 10.1039/c7dt04859a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The terminal formate complex [(OCHO)Ti(N3N)] (3) containing the trianionic triamido-amine ligand (Me3SiNCH2CH2)3N3- (N3N) was prepared via salt metathesis of [ClTi(N3N)] (1) with sodium formate or alternatively by treatment of the alkyl complex [nBuTi(N3N)] (2) with ammonium formate [HNEt3][OCHO]. Deprotonation of 3 with potassium hexamethyldisilazide gave a polymeric helical chain of the oxo complex {K[OTi(N3N)]}n (4). Reaction of 2 with the trityl salt [Ph3C][B(3,5-Cl2C6H3)4] or the Brønsted acid [HNEt3][B(C6F5)4] gave [(Et2O)Ti(N3N)][BR4] (6[BR4]·Et2O) with R = 3,5-Cl2C6H3 or C6F5. The diethyl ether ligand was easily replaced by other L-type donor ligands such as tetrahydrofuran, pyridine, and 4-dimethylaminopyridine to give 6[BR4]·L with L = thf, py, and dmap. Reaction of 6[BR4]·Et2O with a stoichiometric amount of CO2 gave the dimeric, dicationic bis(carbamate)-bridged complexes [Ti{N(CH2CH2NSiMe3)2(CH2CH2NSiMe3(μ-CO2-ηO:ηO'))}]2[BR4]2 (7[BR4]2) through insertion of one CO2 into one of the titanium-amido bonds. Addition of pyridine to 7[B(C6F5)4]2 formed the monomeric carbamate complex [(py)Ti{((O2C-κ2O,O')NSiMe3CH2CH2)N(CH2CH2NSiMe3)2}][B(C6F5)4] (8[B(C6F5)4]·py). The cationic formate-bridged species [(Ti(N3N))2(μ-OCHO-ηO:ηO')][BR4] (10[BR4]) readily formed when the terminal formate complex 3 was reacted with the cationic 6[BR4]. The reactivity of triamido-amine stabilized titanium(iv) complexes is shown to differ considerably from that of related titanium tris(anilide) complexes.
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Affiliation(s)
- A Paparo
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen, Germany.
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16
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Steffensmeier E, Nicholas KM. Oxidation–reductive coupling of alcohols catalyzed by oxo-vanadium complexes. Chem Commun (Camb) 2018; 54:790-793. [DOI: 10.1039/c7cc08387d] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Oxo-vanadium complexes catalyze the novel oxidation–reductive coupling of benzylic and allylic alcohols.
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17
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Wickramasinghe LA, Ogawa T, Schrock RR, Müller P. Reduction of Dinitrogen to Ammonia Catalyzed by Molybdenum Diamido Complexes. J Am Chem Soc 2017. [DOI: 10.1021/jacs.7b04800] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Lasantha A. Wickramasinghe
- Department of Chemistry 6-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Takaya Ogawa
- Department of Chemistry 6-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Richard R. Schrock
- Department of Chemistry 6-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Peter Müller
- Department of Chemistry 6-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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18
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Kasner GR, Boucher-Jacobs C, Michael McClain J, Nicholas KM. Oxo-rhenium catalyzed reductive coupling and deoxygenation of alcohols. Chem Commun (Camb) 2016; 52:7257-60. [DOI: 10.1039/c6cc00537c] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Representative benzylic, allylic and α-keto alcohols are deoxygenated to alkanes and/or reductively coupled to alkane dimers by reaction with PPh3 catalyzed by (PPh3)2ReIO2 (1).
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19
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Geng C, Hao X, Jiao P. Crystal structure of nitridobis(tri-methyl-silanolato)[1,1,1-trimethyl-N-(tri-methyl-sil-yl)silanaminato]molybdenum(VI). Acta Crystallogr E Crystallogr Commun 2015; 71:1497-500. [PMID: 26870413 PMCID: PMC4719822 DOI: 10.1107/s2056989015021192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 11/08/2015] [Indexed: 11/10/2022]
Abstract
In the title compound, [Mo(C6H18NSi2)(C3H9OSi)2N], the Mo(VI) cation is located on a mirror plane and is coordinated by a nitride anion, a 1,1,1-trimethyl-N-(tri-methyl-sil-yl)silanaminate anion and two tri-methyl-silanolate anions in a distorted tetra-hedral geometry; the N atom and two Si atoms of the 1,1,1-trimethyl-N-(tri-methyl-sil-yl)silanaminato anionic ligand are also located on the mirror plane. The Mo N bond length of 1.633 (6) Å is much shorter than the Mo-N single-bond length of 1.934 (7) Å. No hydrogen bonding is observed in the crystal structure.
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Affiliation(s)
- Caiwei Geng
- College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
| | - Xiang Hao
- Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Peng Jiao
- College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
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20
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Paparo A, Silvia JS, Kefalidis CE, Spaniol TP, Maron L, Okuda J, Cummins CC. A Dimetalloxycarbene Bonding Mode and Reductive Coupling Mechanism for Oxalate Formation from CO2. Angew Chem Int Ed Engl 2015; 54:9115-9. [PMID: 26110967 DOI: 10.1002/anie.201502532] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Indexed: 02/03/2023]
Abstract
We describe the stable and isolable dimetalloxycarbene [(TiX3 )2 (μ2 -CO2 -κ(2) C,O:κO')] 5, where X=N-(tert-butyl)-3,5-dimethylanilide, which is stabilized by fluctuating μ2 -κ(2) C,O:κ(1) O' coordination of the carbene carbon to both titanium centers of the dinuclear complex 5, as shown by variable-temperature NMR studies. Quantum chemical calculations on the unmodified molecule indicated a higher energy of only +10.5 kJ mol(-1) for the μ2 -κ(1) O:κ(1) O' bonding mode of the free dimetalloxycarbene compared to the μ2 -κ(2) C,O:κ(1) O' bonding mode of the masked dimetalloxycarbene. The parent cationic bridging formate complex [(TiX3 )2 (μ2 -OCHO-κO:κO')][B(C6 F5)4], 4[B(C6 F5)4], was simply deprotonated with the strong base K(N(SiMe3 )2 ) to give 5. Complex 5 reacts smoothly with CO2 to generate the bridging oxalate complex [(TiX3 )2 (μ2 -C2 O4 -κO:κO'')], 6, in a C-C bond formation reaction commonly anticipated for oxalate formation by reductive coupling of CO2 on low-valent transition-metal complexes.
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Affiliation(s)
- Albert Paparo
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen (Germany)
| | - Jared S Silvia
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 (USA)
| | - Christos E Kefalidis
- Université de Toulouse et CNRS, INSA, UPS, CNRS; UMR 5215 LPCNO, 135 Avenue de Rangueil, 31077 Toulouse (France)
| | - Thomas P Spaniol
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen (Germany)
| | - Laurent Maron
- Université de Toulouse et CNRS, INSA, UPS, CNRS; UMR 5215 LPCNO, 135 Avenue de Rangueil, 31077 Toulouse (France).
| | - Jun Okuda
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen (Germany).
| | - Christopher C Cummins
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 (USA).
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21
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Paparo A, Silvia JS, Kefalidis CE, Spaniol TP, Maron L, Okuda J, Cummins CC. Ein Dimetalloxycarben-Bindungsmodus und der reduktive Kupplungsmechanismus zur Bildung von Oxalat ausgehend von CO2. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201502532] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Braunschweig H, Dewhurst RD, Kramer T. Synthesis of the First Heteroaryl-Substituted Boryl Complexes: Strong Stabilizing Effects of Boron–Aryl π-Conjugation. Inorg Chem 2015; 54:3619-23. [DOI: 10.1021/acs.inorgchem.5b00192] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Holger Braunschweig
- Institut für Anorganische
Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Rian D. Dewhurst
- Institut für Anorganische
Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Thomas Kramer
- Institut für Anorganische
Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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23
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Spinney HA, Clough CR, Cummins CC. The titanium tris-anilide cation [Ti(N[tBu]Ar)3]+ stabilized as its perfluoro-tetra-phenylborate salt: structural characterization and synthesis in connection with redox activity of 4,4′-bipyridine dititanium complexes. Dalton Trans 2015; 44:6784-96. [DOI: 10.1039/c5dt00105f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A rare cationic d0 metal tris-amide complex, containing an intriguing pyramidal TiN3 core geometry, namely {Ti(N[tBu]Ar)3}+, is isolated as its [B(C6F5)4]− salt.
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Affiliation(s)
- Heather A. Spinney
- 6-435 Department of Chemistry
- Massachusetts Institute of Technology
- Cambridge
- USA
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24
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Braunschweig H, Damme A, Dewhurst RD, Kramer T, Krummenacher I, Phukan AK. Short Survey of the Chemical Reduction Behavior of the Base-Stabilized Iron Dichloroboryl Complexes [(η5-C5Me5)Fe(CO)2BCl2(LB)]. Organometallics 2014. [DOI: 10.1021/om401176h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Holger Braunschweig
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Alexander Damme
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Rian D. Dewhurst
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Thomas Kramer
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ivo Krummenacher
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ashwini K. Phukan
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Department of Chemical Sciences, Tezpur University, Napaam 784028, Assam, India
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25
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Semproni SP, Chirik PJ. Activation of Dinitrogen-Derived Hafnium Nitrides for Nucleophilic NC Bond Formation with a Terminal Isocyanate. Angew Chem Int Ed Engl 2013; 52:12965-9. [DOI: 10.1002/anie.201307097] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Indexed: 11/08/2022]
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26
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Semproni SP, Chirik PJ. Activation of Dinitrogen-Derived Hafnium Nitrides for Nucleophilic NC Bond Formation with a Terminal Isocyanate. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201307097] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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27
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Zhou W, MacLeod KC, Patrick BO, Smith KM. Controlling Secondary Alkyl Radicals: Ligand Effects in Chromium-Catalyzed C–P Bond Formation. Organometallics 2012. [DOI: 10.1021/om300846u] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Wen Zhou
- Department of Chemistry, University of British Columbia Okanagan, 3333 University Way, Kelowna,
British Columbia, Canada V1V 1V7
| | - K. Cory MacLeod
- Department of Chemistry, University of British Columbia Okanagan, 3333 University Way, Kelowna,
British Columbia, Canada V1V 1V7
| | - Brian O. Patrick
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
V6T 1Z1
| | - Kevin M. Smith
- Department of Chemistry, University of British Columbia Okanagan, 3333 University Way, Kelowna,
British Columbia, Canada V1V 1V7
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28
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Figueroa JS, Piro NA, Mindiola DJ, Fickes MG, Cummins CC. Niobaziridine Hydrides. Organometallics 2010. [DOI: 10.1021/om100522p] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Joshua S. Figueroa
- Department of Chemistry, Massachusetts Institute of Technology, Room 6-435, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States
| | - Nicholas A. Piro
- Department of Chemistry, Massachusetts Institute of Technology, Room 6-435, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States
| | - Daniel J. Mindiola
- Department of Chemistry, Massachusetts Institute of Technology, Room 6-435, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States
| | - Michael G. Fickes
- Department of Chemistry, Massachusetts Institute of Technology, Room 6-435, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States
| | - Christopher C. Cummins
- Department of Chemistry, Massachusetts Institute of Technology, Room 6-435, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States
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29
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Cossairt BM, Cummins CC. Radical synthesis of trialkyl, triaryl, trisilyl and tristannyl phosphines from P4. NEW J CHEM 2010. [DOI: 10.1039/c0nj00124d] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Cossairt BM, Cummins CC. Properties and Reactivity Patterns of AsP3: An Experimental and Computational Study of Group 15 Elemental Molecules. J Am Chem Soc 2009; 131:15501-11. [DOI: 10.1021/ja906294m] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Brandi M. Cossairt
- Massachusetts Institute of Technology, Department of Chemistry, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
| | - Christopher C. Cummins
- Massachusetts Institute of Technology, Department of Chemistry, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
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31
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Brookes NJ, Ariafard A, Stranger R, Yates BF. Reactivity of CO2 towards Mo[N(R)Ph]3. Dalton Trans 2009:9266-72. [DOI: 10.1039/b909982d] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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32
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Cossairt B, Cummins C. A Reactive Niobium Phosphinidene P8 Cluster Obtained by Reductive Coupling of White Phosphorus. Angew Chem Int Ed Engl 2008; 47:169-72. [DOI: 10.1002/anie.200704354] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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33
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Cossairt B, Cummins C. A Reactive Niobium Phosphinidene P8 Cluster Obtained by Reductive Coupling of White Phosphorus. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200704354] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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34
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Cummins CC. Terminal, anionic carbide, nitride, and phosphide transition-metal complexes as synthetic entries to low-coordinate phosphorus derivatives. Angew Chem Int Ed Engl 2007; 45:862-70. [PMID: 16385612 DOI: 10.1002/anie.200503327] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Anionic terminal one-atom nitride, phosphide, and carbide complexes are excellent starting materials for the synthesis of ligands containing low-coordinate phosphorus centers in the protecting coordination sphere of the metal complex. Salt-elimination reactions with chlorophosphanes lead to phosphaisocyanide, iminophosphinimide, and diorganophosphanylphosphinidene complexes in which the unusual phosphorus ligands are stabilized by coordination. X-ray structure analyses and density-functional calculations illuminate the bonding in these compounds.
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Affiliation(s)
- Christopher C Cummins
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA.
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35
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Agarwal P, Piro N, Meyer K, Müller P, Cummins C. An Isolable and Monomeric Phosphorus Radical That Is Resonance-Stabilized by the Vanadium(IV/V) Redox Couple. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200700059] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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36
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Agarwal P, Piro NA, Meyer K, Müller P, Cummins CC. An Isolable and Monomeric Phosphorus Radical That Is Resonance-Stabilized by the Vanadium(IV/V) Redox Couple. Angew Chem Int Ed Engl 2007; 46:3111-4. [PMID: 17351998 DOI: 10.1002/anie.200700059] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Paresh Agarwal
- Department of Chemistry, Massachusetts Institute of Technology, Room 6-435, Cambridge, MA 02139-4307, USA
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37
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Cummins CC. Three-Coordinate Complexes of “Hard” Ligands: Advances in Synthesis, Structure and Reactivity. PROGRESS IN INORGANIC CHEMISTRY 2007. [DOI: 10.1002/9780470166482.ch7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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38
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Johnson AR, Cummins CC, Gambarotta S. N-Tert
-Alkyl-anilides as Bulky Anciliary Ligands. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/9780470132630.ch20] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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39
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Christian G, Stranger R, Yates BF, Cummins CC. Rationalizing the different products in the reaction of N2 with three-coordinate MoL3 complexes. Dalton Trans 2007:1939-47. [PMID: 17702174 DOI: 10.1039/b701050h] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction of N2 with three-coordinate MoL3 complexes is known to give rise to different products, N-MoL3, L3Mo-N-MoL3 or Mo2L6, depending on the nature of the ligand L. The energetics of the different reaction pathways are compared for L = NH2, NMe2, N((i)Pr)Ar and N((t)Bu)Ar (Ar = 3,5-C6H3Me2) using density functional methods in order to rationalize the experimental results. Overall, the exothermicity of each reaction pathway decreases as the ligand size increases, largely due to the increased steric crowding in the products compared to reactants. In the absence of steric strain, the formation of the metal-metal bonded dimer, Mo2L6, is the most exothermic pathway but this reaction shows the greatest sensitivity to ligand size varying from significantly exothermic, -403 kJ mol(-1) for L = NMe2, to endothermic, +78 kJ mol(-1) for L = N((t)Bu)Ar. For all four ligands, formation of N-MoL3 via cleavage of the N2 bridged dimer intermediate, L3Mo-N-N-MoL3, is strongly exothermic. However, in the presence of excess reactant MoL3, formation of the single atom-bridged complex L3Mo-N-MoL3 from N-MoL3 + MoL3 is both thermodynamically and kinetically favoured for L = NMe2 and N((i)Pr)Ar, in agreement with experiment. In the case of L = N((t)Bu)Ar, the greater steric bulk of the (t)Bu group results in a much less exothermic reaction and a calculated barrier of 66 kJ mol(-1) to formation of the L3Mo-N-MoL3 dimer. Consequently, for this ligand, the energetically and kinetically favoured product, consistent with the experimental data, is the nitride complex L3Mo-N.
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Affiliation(s)
- Gemma Christian
- Department of Chemistry, Faculty of Science, Australian National University, Canberra, ACT 0200, Australia
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40
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Errington RJ, Petkar SS, Middleton PS, McFarlane W, Clegg W, Coxall RA, Harrington RW. Non-aqueous synthetic methodology for TiW5 polyoxometalates: protonolysis of [(MeO)TiW5O18]3– with alcohols, water and phenols. Dalton Trans 2007:5211-22. [DOI: 10.1039/b709732h] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Nielson AJ, Shen C, Waters JM. Molecular engineering of coordination pockets in chloro-tris-phenoxo complexes of titanium(IV). Polyhedron 2006. [DOI: 10.1016/j.poly.2005.12.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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42
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Mendiratta A, Cummins CC, Cotton FA, Ibragimov SA, Murillo CA, Villagrán D. A Diamagnetic Dititanium(III) Paddlewheel Complex with No Direct Metal−Metal Bond. Inorg Chem 2006; 45:4328-30. [PMID: 16711677 DOI: 10.1021/ic0602650] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reaction of Ti[N(But)Ar]3 (Ar = 3,5-C6H3Me2 or Ar' = C6H5) with CO2 at -40 degrees C produces diamagmetic Ti(III) paddlewheel complexes with long Ti-Ti separations (>3.4 Angstrom), thus excluding direct Ti-Ti bonding. 1H NMR spectroscopy shows that the compounds are diamagnetic in solution in the temperature range of -65 to +70 degrees C. In the solid state, the diamagnetism was found to persist between 2 and 300 K. Calculations at the density functional theory level suggest that the diamagnetism results from antiferromagnetic coupling by superexchange through the ligand pi system.
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Affiliation(s)
- Arjun Mendiratta
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA
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43
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Anionische Übergangsmetallkomplexe mit terminalen Carbid-, Nitrid- und Phosphidliganden als Synthesebausteine für niederkoordinierte Phosphorverbindungen. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200503327] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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44
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Figueroa JS, Cummins CC. A niobaziridine hydride system for white phosphorus or dinitrogen activation and N- or P-atom transfer. Dalton Trans 2006:2161-8. [PMID: 16673028 DOI: 10.1039/b602530g] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This short review describes a breakthrough embodied by the synthesis of a niobaziridine hydride complex. This reactive entity reacts directly with white phosphorus to provide a bridging diphosphorus diniobium complex that upon reduction splits to afford a terminal niobium phosphide anion, isolated as its sodium salt. Reactions of the latter with acid chlorides constitute a new synthesis of phosphaalkynes, while treatment with chlorodiorganophosphanes leads to complexed 1,1-diorganophosphanylphosphinidene systems. Additionally, reactions of the sodium salt of the niobium phosphide anion with divalent main group element salts (E = Ge, Sn, or Pb) provide complexed triatomic EP2 triangles. Dinitrogen cleavage was realized via reduction of a heterodinuclear niobium/molybdenum dinitrogen complex, and this provided an entry to a nitrogen-15 labeled terminal nitride anion of niobium as its sodium salt. In a fashion analogous to the aforementioned phosphaalkyne synthesis, acid chlorides are transformed upon reaction with the niobium nitride anion into corresponding nitrogen-15 labeled organic nitriles. Complete synthetic cycles are achieved in both the phosphaalkyne and the organic nitrile syntheses, as the oxoniobium(v) byproduct can be recycled in high yield to the title niobaziridine hydride complex.
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Affiliation(s)
- Joshua S Figueroa
- 2-227 Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
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45
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Gdula RL, Johnson MJA, Ockwig NW. Nitrogen-Atom Exchange Mediated by Nitrido Complexes of Molybdenum. Inorg Chem 2005; 44:9140-2. [PMID: 16323893 DOI: 10.1021/ic051859q] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitrido complexes NMo(OC(CF3)2Me)3 and NMo(OC(CF3)3)3(NCMe) containing fluorinated alkoxide ancillary ligands are synthesized in 57% and 50% yield, respectively. Both complexes undergo N-atom exchange within hours at 30 degrees C with acetonitrile and benzonitrile in either THF-d8 or CD2Cl2, as shown by 15N NMR studies using labeled 15NCMe. In both solvents, is the more active in this process. Additionally, both compounds are substantially more active in THF-d8 than in CD2Cl2. Complex crystallizes in the space group P2(1)/c, adopting a pseudo-square-pyramidal structure in which the nitrido moiety occupies the apical position, 1.633(3) A away from Mo.
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Affiliation(s)
- Robyn L Gdula
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, USA
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46
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Mendiratta A, Figueroa JS, Cummins CC. Synthesis of a four-coordinate titanium(iv) oxoanion via deprotonation and decarbonylation of complexed formate. Chem Commun (Camb) 2005:3403-5. [PMID: 15997278 DOI: 10.1039/b504492h] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Deprotonation of the titanium formate complex [Ar(t-Bu)N]3TiOC(O)H with LiN(i-Pr)2 resulted in the release of free CO and the formation of a titanium(IV) oxoanion complex, isolated as its lithium salt.
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Affiliation(s)
- Arjun Mendiratta
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Room 2-227, Cambridge, MA 02139, USA
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47
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Agapie T, Diaconescu PL, Cummins CC. Methine (CH) transfer via a chlorine atom abstraction/benzene-elimination strategy: molybdenum methylidyne synthesis and elaboration to a phosphaisocyanide complex. J Am Chem Soc 2002; 124:2412-3. [PMID: 11890770 DOI: 10.1021/ja017278r] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methine (CH) transfer to an open coordination site was achieved in one pot by titanium(III) abstraction of Cl from 7-chloronorbornadiene, radical capture by Mo, and benzene extrusion. This efficient Mo methylidyne synthesis permitted elaboration to an anionic phosphaisocyanide derivative upon deprotonation, functionalization with dichlorophenylphosphine, and ultimate reduction.
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Affiliation(s)
- Theodor Agapie
- Department of Chemistry, Room 2-227, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
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48
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Agapie T, Diaconescu PL, Mindiola DJ, Cummins CC. Radical Scission of Symmetrical 1,4-Dicarbonyl Compounds: C−C Bond Cleavage with Titanium(IV) Enolate Formation and Related Reactions. Organometallics 2002. [DOI: 10.1021/om0107284] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Theodor Agapie
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307
| | - Paula L. Diaconescu
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307
| | - Daniel J. Mindiola
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307
| | - Christopher C. Cummins
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307
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Kim GS, DeKock CW. Syntheses, molecular structures, and dynamic solution behavior of nitrido (oxo) molybdenum(VI) siloxides. Polyhedron 2000. [DOI: 10.1016/s0277-5387(00)00423-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Caselli A, Solari E, Scopelliti R, Floriani C, Re N, Rizzoli C, Chiesi-Villa A. Dinitrogen Rearranging over a Metal−Oxo Surface and Cleaving to Nitride: From the End-On to the Side-On Bonding Mode, to the Stepwise Cleavage of the N⋮N Bonds Assisted by NbIII-calix[4]arene. J Am Chem Soc 2000. [DOI: 10.1021/ja9943288] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alessandro Caselli
- Contribution from the Institut de Chimie Minérale et Analytique, BCH, Université de Lausanne, CH-1015 Lausanne, Switzerland, Facoltà di Farmacia, Università degli Studi “G. D'Annunzio”, I-66100 Chieti, Italy, and Dipartimento di Chimica, Università di Parma, I-43100 Parma, Italy
| | - Euro Solari
- Contribution from the Institut de Chimie Minérale et Analytique, BCH, Université de Lausanne, CH-1015 Lausanne, Switzerland, Facoltà di Farmacia, Università degli Studi “G. D'Annunzio”, I-66100 Chieti, Italy, and Dipartimento di Chimica, Università di Parma, I-43100 Parma, Italy
| | - Rosario Scopelliti
- Contribution from the Institut de Chimie Minérale et Analytique, BCH, Université de Lausanne, CH-1015 Lausanne, Switzerland, Facoltà di Farmacia, Università degli Studi “G. D'Annunzio”, I-66100 Chieti, Italy, and Dipartimento di Chimica, Università di Parma, I-43100 Parma, Italy
| | - Carlo Floriani
- Contribution from the Institut de Chimie Minérale et Analytique, BCH, Université de Lausanne, CH-1015 Lausanne, Switzerland, Facoltà di Farmacia, Università degli Studi “G. D'Annunzio”, I-66100 Chieti, Italy, and Dipartimento di Chimica, Università di Parma, I-43100 Parma, Italy
| | - Nazzareno Re
- Contribution from the Institut de Chimie Minérale et Analytique, BCH, Université de Lausanne, CH-1015 Lausanne, Switzerland, Facoltà di Farmacia, Università degli Studi “G. D'Annunzio”, I-66100 Chieti, Italy, and Dipartimento di Chimica, Università di Parma, I-43100 Parma, Italy
| | - Corrado Rizzoli
- Contribution from the Institut de Chimie Minérale et Analytique, BCH, Université de Lausanne, CH-1015 Lausanne, Switzerland, Facoltà di Farmacia, Università degli Studi “G. D'Annunzio”, I-66100 Chieti, Italy, and Dipartimento di Chimica, Università di Parma, I-43100 Parma, Italy
| | - Angiola Chiesi-Villa
- Contribution from the Institut de Chimie Minérale et Analytique, BCH, Université de Lausanne, CH-1015 Lausanne, Switzerland, Facoltà di Farmacia, Università degli Studi “G. D'Annunzio”, I-66100 Chieti, Italy, and Dipartimento di Chimica, Università di Parma, I-43100 Parma, Italy
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