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Shiau AA, Lee HB, Oyala PH, Agapie T. Mn IV4O 4 Model of the S 3 Intermediate of the Oxygen-Evolving Complex: Effect of the Dianionic Disiloxide Ligand. Inorg Chem 2023; 62:1791-1796. [PMID: 35829634 PMCID: PMC11472716 DOI: 10.1021/acs.inorgchem.2c01612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Synthetic complexes provide useful models to study the interplay between the structure and spectroscopy of the different Sn-state intermediates of the oxygen-evolving complex (OEC) of photosystem II (PSII). Complexes containing the MnIV4 core corresponding to the S3 state, the last observable intermediate prior to dioxygen formation, remain very rare. Toward the development of synthetic strategies to stabilize highly oxidized tetranuclear complexes, ligands with increased anion charge were pursued. Herein, we report the synthesis, electrochemistry, SQUID magnetometry, and electron paramagnetic resonance spectroscopy of a stable MnIV4O4 cuboidal complex supported by a disiloxide ligand. The substitution of an anionic acetate or amidate ligand with a dianionic disiloxide ligand shifts the reduction potential of the MnIIIMnIV3/MnIV4 redox couple by up to ∼760 mV, improving stability. The S = 3 spin ground state of the siloxide-ligated MnIV4O4 complex matches the acetate and amidate variants, in corroboration with the MnIV4 assignment of the S3 state of the OEC.
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Affiliation(s)
- Angela A Shiau
- Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Heui Beom Lee
- Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Paul H Oyala
- Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Theodor Agapie
- Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
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Wang N, Feng B, Cui P, Tamm M, Chen Y. Imidazolin-2-iminato Cerium(IV) Chlorides: Synthesis, Structure and Electrochemical Properties. Chem Asian J 2023; 18:e202201135. [PMID: 36445801 DOI: 10.1002/asia.202201135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 11/27/2022] [Accepted: 11/28/2022] [Indexed: 11/30/2022]
Abstract
The ligand field greatly affects the redox properties of cerium. Herein, cerium(III) and cerium(IV) complexes supported by imidazolin-2-iminato ligands were synthesized and structurally characterized, and their electrochemical properties were investigated. Silylamine elimination of cerium(III) amide Ce{N(SiMe3 )2 }3 with imidazolin-2-imine ImR NH (R=Mes, tBu, iPr) provided imidazolin-2-iminato cerium(III) complexes, [(ImMes N)(ImMes NH)Ce{N(SiMe3 )2 }2 ] (1), [(ImtBu N)2 (ImtBu NH)Ce{N(SiMe3 )2 }] (2) and [(ImiPr N)2 (ImiPr NH)Ce(μ-ImiPr N)]2 (4) in 71-85% yields. These cerium(III) complexes were successfully oxidized by Ph3 CCl or C2 Cl6 to afford imidazolin-2-iminato cerium(IV) chlorides, [(ImMes N)2 Ce{N(SiMe3 )2 }Cl] (5), [(ImtBu N)3 CeCl] (6) and [(ImiPr N)2 Ce(μ-ImiPr N)Cl]2 (7) in 70%-76% yields. All complexes were characterized by the single-crystal X-ray diffraction, which showed that 1, 2, 5 and 6 are monomers while 4 and 7 are dimers. The electrochemical studies indicated that the Ce(III/IV) couples for 5 and 6 are more negative than those of silylamido cerium(IV) complexes, and the Ce(III/IV) couples for 1 and 2 have a similar trend.
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Affiliation(s)
- Ning Wang
- Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, P. R. China.,State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, P. R. China
| | - Bin Feng
- State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, P. R. China
| | - Peng Cui
- Key Laboratory of Functional Molecular Solids Ministry of Education Anhui Laboratory of Molecule-Based Materials, College of Chemistry and Materials ScienceAnhui Normal University, S189 Jiuhua Road, Wuhu, Anhui, 241002, P. R. China
| | - Matthias Tamm
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany
| | - Yaofeng Chen
- State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, P. R. China.,Spin-X Institute School of Chemistry and Chemical Engineering Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, 510641, P. R. China
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Willauer AR, Douair I, Chauvin AS, Fadaei-Tirani F, Bünzli JCG, Maron L, Mazzanti M. Structure, reactivity and luminescence studies of triphenylsiloxide complexes of tetravalent lanthanides. Chem Sci 2022; 13:681-691. [PMID: 35173932 PMCID: PMC8769062 DOI: 10.1039/d1sc05517h] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/15/2021] [Indexed: 12/03/2022] Open
Abstract
Among the 14 lanthanide elements (Ce–Lu), until recently, the tetravalent oxidation state was readily accessible in solution only for cerium while Pr(iv), Nd(iv), Dy(iv) and Tb(iv) had only been detected in the solid state. The triphenylsiloxide ligand recently allowed the isolation of molecular complexes of Tb(iv) and Pr(iv) providing an unique opportunity of investigating the luminescent properties of Ln(iv) ions. Here we have expanded the coordination studies of the triphenylsiloxide ligand with Ln(iii) and Ln(iv) ions and we report the first observed luminescence emission spectra of Pr(iv) complexes which are assigned to a ligand-based emission on the basis of the measured lifetime and computational studies. Binding of the ligand to the Pr(iv) ion leads to an unprecedented large shift of the ligand triplet state which is relevant for future applications in materials science. The first observed luminescence emission spectra of Pr(iv) complexes are assigned to a ligand-based emission. Binding of the triphenylsiloxide ligand to the Pr(iv) ion leads to an unprecedented large red shift of its triplet state.![]()
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Affiliation(s)
- Aurélien R Willauer
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Iskander Douair
- Laboratoire de Physique et Chimie des Nano-objets, Institut National des Sciences Appliquées 31077 Toulouse France
| | - Anne-Sophie Chauvin
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Farzaneh Fadaei-Tirani
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Jean-Claude G Bünzli
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland .,Department of Biomedical Engineering, Southern University of Science and Technology (SUSTech) Shenzhen China
| | - Laurent Maron
- Laboratoire de Physique et Chimie des Nano-objets, Institut National des Sciences Appliquées 31077 Toulouse France
| | - Marinella Mazzanti
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
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Hirneise L, Maichle-Mössmer C, Anwander R. Pentamethylcyclopentadienyl Complexes of Cerium(IV): Synthesis, Reactivity, and Electrochemistry. Inorg Chem 2021; 60:18211-18224. [PMID: 34779192 DOI: 10.1021/acs.inorgchem.1c02851] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Treatment of Cp*2CeCl2K(THF) with alkali-metal alkoxides and siloxides in the presence of hexachloroethane generates the monomeric bis(pentamethylcyclopentadienyl) cerium(IV) complexes Cp*2Ce(OR)2 (Cp* = C5Me5; R = Et, iPr, CH2tBu, tBu, SiMe3, or SiPh3). Large substituents R trigger ligand scrambling to half-sandwich complexes Cp*Ce(OR)3, which could be isolated for R = tBu and SiPh3. Similar reactions with sodium aryloxide NaOAr (OAr = OC6H3iPr2-2,6) led to Cp*2Ce(OAr)Cl. Treatment of tris(cyclopentadienyl) complexes CpR3CeCl (CpH = Cp = C5H5; CpMe = C5H4Me) with NaOAr afforded CpMe2Ce(OAr)2 and Cp3Ce(OAr). The cerium(IV) complexes display a pseudotetrahedral geometry in the solid state. Cyclic voltammetry revealed mostly chemically reversible as well as electrochemically quasi-reversible redox processes with potentials ranging from -0.84 to -1.61 V versus Fc/Fc+. Switching from sandwich to half-sandwich complexes decreased the electrochemical potentials drastically, showing better stabilization of the cerium(IV) center in the case of Cp*Ce(OR)3 than in the case of Cp*2Ce(OR)2. Enhanced stabilization of the cerium +IV oxidation state could be further demonstrated in the series alkoxy > siloxy > aryloxy as well as C5Me5 > C5HMe4.
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Affiliation(s)
- Lars Hirneise
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Cäcilia Maichle-Mössmer
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Reiner Anwander
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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Hirneise L, Langmann J, Zitzer G, Ude L, Maichle-Mössmer C, Scherer W, Speiser B, Anwander R. Tuning Organocerium Electrochemical Potentials by Extending Tris(cyclopentadienyl) Scaffolds with Terminal Halogenido, Siloxy, and Alkoxy Ligands. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00276] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Lars Hirneise
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Jan Langmann
- Institut für Physik, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg, Germany
| | - Georg Zitzer
- Institut für Organische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Lukas Ude
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Cäcilia Maichle-Mössmer
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Wolfgang Scherer
- Institut für Physik, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg, Germany
| | - Bernd Speiser
- Institut für Organische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Reiner Anwander
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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Hay MA, Boskovic C. Lanthanoid Complexes as Molecular Materials: The Redox Approach. Chemistry 2021; 27:3608-3637. [PMID: 32965741 DOI: 10.1002/chem.202003761] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Indexed: 11/05/2022]
Abstract
The development of molecular materials with novel functionality offers promise for technological innovation. Switchable molecules that incorporate redox-active components are enticing candidate compounds due to their potential for electronic manipulation. Lanthanoid metals are most prevalent in their trivalent state and usually redox-activity in lanthanoid complexes is restricted to the ligand. The unique electronic and physical properties of lanthanoid ions have been exploited for various applications, including in magnetic and luminescent materials as well as in catalysis. Lanthanoid complexes are also promising for applications reliant on switchability, where the physical properties can be modulated by varying the oxidation state of a coordinated ligand. Lanthanoid-based redox activity is also possible, encompassing both divalent and tetravalent metal oxidation states. Thus, utilization of redox-active lanthanoid metals offers an attractive opportunity to further expand the capabilities of molecular materials. This review surveys both ligand and lanthanoid centered redox-activity in pre-existing molecular systems, including tuning of lanthanoid magnetic and photophysical properties by modulating the redox states of coordinated ligands. Ultimately the combination of redox-activity at both ligands and metal centers in the same molecule can afford novel electronic structures and physical properties, including multiconfigurational electronic states and valence tautomerism. Further targeted exploration of these features is clearly warranted, both to enhance understanding of the underlying fundamental chemistry, and for the generation of a potentially important new class of molecular material.
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Affiliation(s)
- Moya A Hay
- School of Chemistry, University of Melbourne, Victoria, 3010, Australia
| | - Colette Boskovic
- School of Chemistry, University of Melbourne, Victoria, 3010, Australia
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Wong KH, Cheung WM, Pham HL, So YM, Sung HHY, Williams ID, Leung WH. Oxidizing Cerium(IV) Alkoxide Complexes Supported by the Kläui Ligand [Co(η 5-C 5H 5){P(O)(OEt) 2} 3] -: Synthesis, Structure, and Redox Reactivity. Inorg Chem 2021; 60:2261-2270. [PMID: 33499604 DOI: 10.1021/acs.inorgchem.0c03105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Tetravalent cerium alkoxide complexes supported by the Kläui tripodal ligand [Co(η5-C5H5){P(O)(OEt)2}3]- (LOEt-) have been synthesized, and their nucleophilic and redox reactivity have been studied. Treatment of the Ce(IV) oxo complex [CeIV(LOEt)2(O)(H2O)]·MeCONH2 (1) with iPrOH or reaction of [CeIV(LOEt)2Cl2] (2) with Ag2O in iPrOH afforded the Ce(IV) dialkoxide complex [CeIV(LOEt)2(OiPr)2] (3-iPr). The methoxide and ethoxide analogues [CeIV(LOEt)2(OR)2] (R = Me (3-Me), Et (3-Et)) have been prepared similarly from 2 and Ag2O in ROH. Reaction of 3-iPr with an equimolar amount of 2 yielded a new Ce(IV) complex that was formulated as the chloro-alkoxide complex [CeIV(LOEt)2(OiPr)Cl] (4). Treatment of 3-iPr with HX and methyl triflate (MeOTf) afforded [Ce(LOEt)2X2] (X- = Cl-, NO3-, PhO-) and [CeIV(LOEt)2(OTf)2], respectively, whereas treatment with excess CO2 in hexane led to isolation of the Ce(IV) carbonate [CeIV(LOEt)2(CO3)]. 3-iPr reacted with water in hexane to give a Ce(III) complex and a Ce(IV) species, presumably the reported tetranuclear oxo cluster [CeIV4(LOEt)4(O)5(OH)2]. The Ce(IV) alkoxide complexes are capable of oxidizing substituted phenols, possibly via a proton-coupled electron transfer pathway. Treatment of 3-iPr with ArOH afforded the Ce(III) aryloxide complexes [CeIII(LOEt)2(OAr)] (Ar = 2,4,6-tri-tert-butylphenyl (5), 2,6-diphenylphenyl (6)). On the other hand, a Ce(III) complex containing a monodeprotonated 2,2'-biphenol ligand, [CeIII(LOEt)2(tBu4C12H4O2H)] (7) (tBu4C12H4O2H2 = 4,4',6,6'-tetra-tert-butyl-2,2'-biphenol), was isolated from the reaction of 3-iPr with 2,4-di-tert-butylphenol. The crystal structures of complexes 3-iPr, 3-Me, 3-Et, and 5-7 have been determined.
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Affiliation(s)
- Kai-Hong Wong
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Wai-Man Cheung
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Hoang-Long Pham
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Yat-Ming So
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Herman H-Y Sung
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Ian D Williams
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Wa-Hung Leung
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
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Qiao Y, Yin H, Moreau LM, Feng R, Higgins RF, Manor BC, Carroll PJ, Booth CH, Autschbach J, Schelter EJ. Cerium(iv) complexes with guanidinate ligands: intense colors and anomalous electronic structures. Chem Sci 2020; 12:3558-3567. [PMID: 34163629 PMCID: PMC8179493 DOI: 10.1039/d0sc05193d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A series of cerium(iv) mixed-ligand guanidinate–amide complexes, {[(Me3Si)2NC(NiPr)2]xCeIV[N(SiMe3)2]3−x}+ (x = 0–3), was prepared by chemical oxidation of the corresponding cerium(iii) complexes, where x = 1 and 2 represent novel complexes. The Ce(iv) complexes exhibited a range of intense colors, including red, black, cyan, and green. Notably, increasing the number of the guanidinate ligands from zero to three resulted in significant redshift of the absorption bands from 503 nm (2.48 eV) to 785 nm (1.58 eV) in THF. X-ray absorption near edge structure (XANES) spectra indicated increasing f occupancy (nf) with more guanidinate ligands, and revealed the multiconfigurational ground states for all Ce(iv) complexes. Cyclic voltammetry experiments demonstrated less stabilization of the Ce(iv) oxidation state with more guanidinate ligands. Moreover, the Ce(iv) tris(guanidinate) complex exhibited temperature independent paramagnetism (TIP) arising from the small energy gap between the ground- and excited states with considerable magnetic moments. Computational analysis suggested that the origin of the low energy absorption bands was a charge transfer between guanidinate π orbitals that were close in energy to the unoccupied Ce 4f orbitals. However, the incorporation of sterically hindered guanidinate ligands inhibited optimal overlaps between Ce 5d and ligand N 2p orbitals. As a result, there was an overall decrease of ligand-to-metal donation and a less stabilized Ce(iv) oxidation state, while at the same time, more of the donated electron density ended up in the 4f shell. The results indicate that incorporating guanidinate ligands into Ce(iv) complexes gives rise to intense charge transfer bands and noteworthy electronic structures, providing insights into the stabilization of tetravalent lanthanide oxidation states. A series of cerium(iv) mixed-ligand guanidinate-amide complexes, {[(Me3Si)2NC(NiPr)2]xCeIV[N(SiMe3)2]3−x}+ (x = 0−3), was prepared by chemical oxidation and studied spectroscopically and computationally, revealing trends in 4f/5d orbital occupancies.![]()
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Affiliation(s)
- Yusen Qiao
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34 Street Philadelphia Pennsylvania 19104 USA .,Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley California 94720 USA
| | - Haolin Yin
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34 Street Philadelphia Pennsylvania 19104 USA
| | - Liane M Moreau
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley California 94720 USA
| | - Rulin Feng
- Department of Chemistry, University at Buffalo, State University of New York Buffalo New York 14260 USA
| | - Robert F Higgins
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34 Street Philadelphia Pennsylvania 19104 USA
| | - Brian C Manor
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34 Street Philadelphia Pennsylvania 19104 USA
| | - Patrick J Carroll
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34 Street Philadelphia Pennsylvania 19104 USA
| | - Corwin H Booth
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley California 94720 USA
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York Buffalo New York 14260 USA
| | - Eric J Schelter
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34 Street Philadelphia Pennsylvania 19104 USA
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Bayer U, Werner D, Berkefeld A, Maichle-Mössmer C, Anwander R. Cerium-quinone redox couples put under scrutiny. Chem Sci 2020; 12:1343-1351. [PMID: 34163897 PMCID: PMC8179043 DOI: 10.1039/d0sc04489j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Homoleptic cerous complexes Ce[N(SiMe3)2]3, [Ce{OSi(OtBu)3}3]2 and [Ce{OSiiPr3}3]2 were employed as thermally robust, weakly nucleophilic precursors to assess their reactivity towards 1,4-quinones in non-aqueous solution. The strongly oxidizing quinones 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or tetrachloro-1,4-benzoquinone (Cl4BQ) readily form hydroquinolato-bridged ceric complexes of the composition [(CeIVL3)2(μ2-O2C6R4)]. Less oxidising quinones like 2,5-di-tert-butyl-1,4-benzoquinone (tBu2BQ) tend to engage in redox equilibria with the ceric hydroquinolato-bridged form being stable only in the solid state. Even less oxidising quinones such as tetramethyl-1,4-benzoquinone (Me4BQ) afford cerous semiquinolates of the type [(CeIIIL2(thf)2)(μ2-O2C6Me4)]2. All complexes were characterised by X-ray diffraction, 1H, 13C{1H} and 29Si NMR spectroscopy, DRIFT spectroscopy, UV-Vis spectroscopy and CV measurements. The species putatively formed during the electrochemical reduction of [CeIV{N(SiMe3)2}3]2(μ2-O2C6H4) could be mimicked by chemical reduction with CoIICp2 yielding [(CeIII{N(SiMe3)2}3)2(μ2-O2C6H4)][CoIIICp2]2.
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Affiliation(s)
- Uwe Bayer
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen (EKUT) Auf der Morgenstelle 18 72076 Tübingen Germany [http://uni-tuebingen.de/syncat-anwander]
| | - Daniel Werner
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen (EKUT) Auf der Morgenstelle 18 72076 Tübingen Germany [http://uni-tuebingen.de/syncat-anwander]
| | - Andreas Berkefeld
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen (EKUT) Auf der Morgenstelle 18 72076 Tübingen Germany [http://uni-tuebingen.de/syncat-anwander]
| | - Cäcilia Maichle-Mössmer
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen (EKUT) Auf der Morgenstelle 18 72076 Tübingen Germany [http://uni-tuebingen.de/syncat-anwander]
| | - Reiner Anwander
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen (EKUT) Auf der Morgenstelle 18 72076 Tübingen Germany [http://uni-tuebingen.de/syncat-anwander]
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Bayer U, Liang Y, Anwander R. Cerium Pyrazolates Grafted onto Mesoporous Silica SBA-15: Reversible CO 2 Uptake and Catalytic Cycloaddition of Epoxides and Carbon Dioxide. Inorg Chem 2020; 59:14605-14614. [PMID: 32975938 DOI: 10.1021/acs.inorgchem.0c02502] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The activation and catalytic conversion of CO2 is a current topic relating to molecular chemistry and materials science alike. As a transdisciplinary field of research, surface organometallic chemistry (SOMC) might be applicable to perform synergistically, thus striking a new path in sustainable chemistry. Both ceric and cerous rare-earth-metal pyrazolates, which were recently shown to reversibly insert CO2 and to promote the catalytic cycloaddition of epoxides and carbon dioxide, were grafted onto large-pore mesoporous silica SBA-15500, thermally pretreated at 500 °C. The obtained hybrid materials [Ce(Me2pz)4]2@SBA-15500, Ce(Me2pz)4(thf)@SBA-15500, Ce4(Me2pz)12@SBA-15500, and [Ce(Me2pz)3(thf)]2@SBA-15500 (Me2pz = 3,5-dimethylpyrazolato) were characterized by DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy), solid-state 1H/13C NMR spectroscopy, elemental analysis, ICP/OES, and N2 physisorption. The lanthanum(III)-based material [La(Me2pz)3(thf)]2@SBA-15500 was synthesized for better assessment of the cerous materials being highly sensitive to oxidation. To mimic ceric surface species, Ce[OSi(OtBu)3]3Cl was treated with 1 equiv of K(Me2pz), generating the mixed pyrazolyl/siloxy complex KCe[OSi(OtBu)3]4(Me2pz) featuring a cerium(IV)-bonded terminal pyrazolato ligand. All hybrid materials show efficient and reversible carbon dioxide uptake of maximum 20 wt % in the solid state. When combined with tetra-n-butylammonium bromide (TBAB), the hybrid materials catalyze the cycloaddition of CO2 and epoxides, displaying good conversion of various epoxides and reusability.
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Affiliation(s)
- Uwe Bayer
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Yucang Liang
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Reiner Anwander
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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Willauer AR, Palumbo CT, Fadaei-Tirani F, Zivkovic I, Douair I, Maron L, Mazzanti M. Accessing the +IV Oxidation State in Molecular Complexes of Praseodymium. J Am Chem Soc 2020; 142:5538-5542. [PMID: 32134644 DOI: 10.1021/jacs.0c01204] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Out of the 14 lanthanide (Ln) ions, molecular complexes of Ln(IV) were known only for cerium and more recently terbium. Here we demonstrate that the +IV oxidation state is also accessible for the large praseodymium (Pr) cation. The oxidation of the tetrakis(triphenysiloxide) Pr(III) ate complex, [KPr(OSiPh3)4(THF)3], 1-PrPh, with [N(C6H4Br)3][SbCl6], affords the Pr(IV) complex [Pr(OSiPh3)4(MeCN)2], 2-PrPh, which is stable once isolated. The solid state structure, UV-visible spectroscopy, magnetometry, and cyclic voltammetry data along with the DFT computations of the 2-PrPh complex unambiguously confirm the presence of Pr(IV).
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Affiliation(s)
- Aurélien R Willauer
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Chad T Palumbo
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Farzaneh Fadaei-Tirani
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ivica Zivkovic
- Laboratory for Quantum Magnetism, Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Iskander Douair
- Laboratoire de Physique et Chimie des Nano-objets, Institut National des Sciences Appliquées, 31077 Toulouse, Cedex 4, France
| | - Laurent Maron
- Laboratoire de Physique et Chimie des Nano-objets, Institut National des Sciences Appliquées, 31077 Toulouse, Cedex 4, France
| | - Marinella Mazzanti
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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12
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Willauer AR, Palumbo CT, Scopelliti R, Zivkovic I, Douair I, Maron L, Mazzanti M. Stabilization of the Oxidation State +IV in Siloxide‐Supported Terbium Compounds. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201914733] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Aurélien R. Willauer
- Institut des Sciences et Ingénierie ChimiquesEcole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Chad T. Palumbo
- Institut des Sciences et Ingénierie ChimiquesEcole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Rosario Scopelliti
- Institut des Sciences et Ingénierie ChimiquesEcole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Ivica Zivkovic
- Laboratory for Quantum MagnetismInstitute of PhysicsEPFL 1015 Lausanne Switzerland
| | - Iskander Douair
- Laboratoire de Physique et Chimie des Nano-objetsInstitut National des Sciences Appliquées 31077 Toulouse, Cedex 4 France
| | - Laurent Maron
- Laboratoire de Physique et Chimie des Nano-objetsInstitut National des Sciences Appliquées 31077 Toulouse, Cedex 4 France
| | - Marinella Mazzanti
- Institut des Sciences et Ingénierie ChimiquesEcole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
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13
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Willauer AR, Palumbo CT, Scopelliti R, Zivkovic I, Douair I, Maron L, Mazzanti M. Stabilization of the Oxidation State +IV in Siloxide‐Supported Terbium Compounds. Angew Chem Int Ed Engl 2020; 59:3549-3553. [DOI: 10.1002/anie.201914733] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Aurélien R. Willauer
- Institut des Sciences et Ingénierie ChimiquesEcole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Chad T. Palumbo
- Institut des Sciences et Ingénierie ChimiquesEcole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Rosario Scopelliti
- Institut des Sciences et Ingénierie ChimiquesEcole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Ivica Zivkovic
- Laboratory for Quantum MagnetismInstitute of PhysicsEPFL 1015 Lausanne Switzerland
| | - Iskander Douair
- Laboratoire de Physique et Chimie des Nano-objetsInstitut National des Sciences Appliquées 31077 Toulouse, Cedex 4 France
| | - Laurent Maron
- Laboratoire de Physique et Chimie des Nano-objetsInstitut National des Sciences Appliquées 31077 Toulouse, Cedex 4 France
| | - Marinella Mazzanti
- Institut des Sciences et Ingénierie ChimiquesEcole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
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14
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Barluzzi L, Falcone M, Mazzanti M. Small molecule activation by multimetallic uranium complexes supported by siloxide ligands. Chem Commun (Camb) 2019; 55:13031-13047. [PMID: 31608910 DOI: 10.1039/c9cc05605j] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The synthesis and reactivity of uranium compounds supported by the tris-tert-butoxysiloxide ligand is surveyed. The multiple binding modes of the tert-butoxysiloxide ligand have proven very well suited to stabilize highly reactive homo- and heteropolymetallic complexes of uranium that have shown an unusual high reactivity towards small molecules such as CO2, CS2, chalcogens and azides. Moreover, these ligands have allowed the isolation of dinuclear nitride and oxide bridged complexes of uranium in various oxidation states. The ability of the tris-tert-butoxysiloxide ligands to trap alkali ions in these nitride or oxide complexes leads to unprecedented ligand based and metal based reduction and functionalization of N2, CO, CO2 and H2.
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Affiliation(s)
- Luciano Barluzzi
- I Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
| | - Marta Falcone
- I Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
| | - Marinella Mazzanti
- I Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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15
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Tsurugi H, Ikeda Y, Shinohara K, Shirase S, Toya N, Tanaka S, Mashima K. Synthesis and Characterization of Alkoxide-Bridged Heterometallic Clusters of Cerium and Copper. Inorg Chem 2019; 58:12565-12572. [DOI: 10.1021/acs.inorgchem.9b01213] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hayato Tsurugi
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yuri Ikeda
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Koichi Shinohara
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Satoru Shirase
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Nozomi Toya
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Shinji Tanaka
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Kazushi Mashima
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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16
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Palumbo CT, Zivkovic I, Scopelliti R, Mazzanti M. Molecular Complex of Tb in the +4 Oxidation State. J Am Chem Soc 2019; 141:9827-9831. [DOI: 10.1021/jacs.9b05337] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Chad T. Palumbo
- Insititut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ivica Zivkovic
- Laboratory for Quantum Magnetism, Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Rosario Scopelliti
- Insititut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Marinella Mazzanti
- Insititut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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17
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Friedrich J, Maichle‐Mössmer C, Schrenk C, Schnepf A, Anwander R. Ceric Ammonium Nitrate and Ceric Ammonium Chloride as Precursors for Ceric Siloxides: Ammonia and Ammonium Inclusion. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201801150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Jochen Friedrich
- Institut für Anorganische Chemie Eberhard Karls Universität Tübingen Auf der Morgenstelle 18 72076 Germany
| | - Cäcilia Maichle‐Mössmer
- Institut für Anorganische Chemie Eberhard Karls Universität Tübingen Auf der Morgenstelle 18 72076 Germany
| | - Claudio Schrenk
- Institut für Anorganische Chemie Eberhard Karls Universität Tübingen Auf der Morgenstelle 18 72076 Germany
| | - Andreas Schnepf
- Institut für Anorganische Chemie Eberhard Karls Universität Tübingen Auf der Morgenstelle 18 72076 Germany
| | - Reiner Anwander
- Institut für Anorganische Chemie Eberhard Karls Universität Tübingen Auf der Morgenstelle 18 72076 Germany
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18
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Werner D, Anwander R. Unveiling the Takai Olefination Reagent via Tris( tert-butoxy)siloxy Variants. J Am Chem Soc 2018; 140:14334-14341. [PMID: 30213182 DOI: 10.1021/jacs.8b08739] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The elusive Takai olefination reagent, namely, the iodo-methylidene Cr(III) complex [Cr2Cl4(CHI)(thf)4], has been isolated by careful handling of the reaction between CrCl2 and CHI3 in THF at -35 °C. Alternatively, treatment of [Cr(OSi(O tBu)3)2] with CHI3 gave the mixed-valent dihalido-methanide complex [CrII/III2I2(OSi(O tBu)3)2(CHI2)], featuring a Cr(III)-CHI2 moiety. In the presence of TMEDA nucleophilic attack at CHI2 occurred generating the zwitterionic species [CrIII(OSi(O tBu)3)2(tmeda-CHI)][I]. Complexes [Cr2Cl4(CHI)(thf)4] and [CrII/III2I2(OSi(O tBu)3)2(CHI2)] were screened for their ability to induce monohalido olefination of benzaldehyde. Remarkably, both complexes promote olefination, with [Cr2Cl4(CHI)(thf)4] accomplishing the same E selectivity as Takai 's original mixture. Complex [CrII/III2I2(OSi(O tBu)3)2(CHI2)], however, appeared to give preferentially Z isomer, corroborating the monoiodo-methylidene species Cr(III)-CHI-Cr(III) as the active olefination component of the original in situ generated Takai reagent mixture.
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Affiliation(s)
- Daniel Werner
- Institut für Anorganische Chemie , Eberhard Karls Universität Tübingen , Auf der Morgenstelle 18 , 72076 Tübingen , Germany
| | - Reiner Anwander
- Institut für Anorganische Chemie , Eberhard Karls Universität Tübingen , Auf der Morgenstelle 18 , 72076 Tübingen , Germany
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