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Jiang W, Rajeshkumar T, Guo M, Lin Y, Maron L, Zhang L. Rare-earth metal ethylene and ethyne complexes. Chem Sci 2024; 15:3495-3501. [PMID: 38455028 PMCID: PMC10915835 DOI: 10.1039/d3sc06599e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 01/26/2024] [Indexed: 03/09/2024] Open
Abstract
Guanidinate homometallic rare-earth ethyl complexes [LLn(μ2-η1:η2-Et)(Et)]2 (Ln = Y(1-Y), Lu(1-Lu)) and heterobimetallic rare-earth ethyl complexes LLn(Et)(μ2-η1:η2-Et)(μ2-η1-Et)(AlEt2) (Ln = Y(2-Y), Lu(2-Lu)) have been synthesized by the treatment of LLn(CH2C6H4NMe2-o)2 (L = (PhCH2)2NC(NC6H3iPr2-2,6)2) with different equivalents of AlEt3 in toluene at ambient temperature. Interestingly, the unprecedented rare-earth ethyne complex [LY(μ2-η1-Et)2(AlEt)]2(μ4-η1:η1:η2:η2-C2H2) (3-Y) containing a [C2H2]4- unit was afforded from 2-Y. The formation mechanism study on 3-Y was carried out by DFT calculations. Furthermore, the nature of the bonding of 3-Y was also revealed by NBO analysis. The reactions of LLn(CH2 C6H4NMe2-o)2 (Ln = Y, Lu) with AlEt3 (4 equiv.) in toluene at 50 °C produced firstly the non-Cp rare-earth ethylene complex LY(μ3-η1:η1:η2-C2H4)[(μ2-η1-Et)(AlEt2)(μ2-η1-Et)2(AlEt)] (4-Y), and the Y/Al ethyl complex LY[(μ2-η1-Et)2(AlEt2)]2 (5-Y) as an intermediate of 4-Y was isolated from the reaction of LY(CH2C6H4NMe2-o)2 with AlEt3 (4 equiv.) in toluene at -10 °C.
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Affiliation(s)
- Wen Jiang
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University 2005 Songhu Road, Jiangwan Campus Shanghai 200438 P. R. China
| | | | - Mengyue Guo
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University 2005 Songhu Road, Jiangwan Campus Shanghai 200438 P. R. China
| | - Yuejian Lin
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University 2005 Songhu Road, Jiangwan Campus Shanghai 200438 P. R. China
| | | | - Lixin Zhang
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University 2005 Songhu Road, Jiangwan Campus Shanghai 200438 P. R. China
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2
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Holmes ST, Schönzart J, Philips AB, Kimball JJ, Termos S, Altenhof AR, Xu Y, O'Keefe CA, Autschbach J, Schurko RW. Structure and bonding in rhodium coordination compounds: a 103Rh solid-state NMR and relativistic DFT study. Chem Sci 2024; 15:2181-2196. [PMID: 38332836 PMCID: PMC10848688 DOI: 10.1039/d3sc06026h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 12/06/2023] [Indexed: 02/10/2024] Open
Abstract
This study demonstrates the application of 103Rh solid-state NMR (SSNMR) spectroscopy to inorganic and organometallic coordination compounds, in combination with relativistic density functional theory (DFT) calculations of 103Rh chemical shift tensors and their analysis with natural bond orbital (NBO) and natural localized molecular orbital (NLMO) protocols, to develop correlations between 103Rh chemical shift tensors, molecular structure, and Rh-ligand bonding. 103Rh is one of the least receptive NMR nuclides, and consequently, there are very few reports in the literature. We introduce robust 103Rh SSNMR protocols for stationary samples, which use the broadband adiabatic inversion-cross polarization (BRAIN-CP) pulse sequence and wideband uniform-rate smooth-truncation (WURST) pulses for excitation, refocusing, and polarization transfer, and demonstrate the acquisition of 103Rh SSNMR spectra of unprecedented signal-to-noise and uniformity. The 103Rh chemical shift tensors determined from these spectra are complemented by NBO/NLMO analyses of contributions of individual orbitals to the 103Rh magnetic shielding tensors to understand their relationship to structure and bonding. Finally, we discuss the potential for these experimental and theoretical protocols for investigating a wide range of materials containing the platinum group elements.
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Affiliation(s)
- Sean T Holmes
- Department of Chemistry & Biochemistry, Florida State University Tallahassee FL 32306 USA
- National High Magnetic Field Laboratory Tallahassee FL 32310 USA
| | - Jasmin Schönzart
- Department of Chemistry & Biochemistry, Florida State University Tallahassee FL 32306 USA
- National High Magnetic Field Laboratory Tallahassee FL 32310 USA
| | - Adam B Philips
- Department of Chemistry, University at Buffalo, State University of New York Buffalo NY 14260-3000 USA
| | - James J Kimball
- Department of Chemistry & Biochemistry, Florida State University Tallahassee FL 32306 USA
- National High Magnetic Field Laboratory Tallahassee FL 32310 USA
| | - Sara Termos
- Department of Chemistry & Biochemistry, Florida State University Tallahassee FL 32306 USA
- National High Magnetic Field Laboratory Tallahassee FL 32310 USA
| | - Adam R Altenhof
- Department of Chemistry & Biochemistry, Florida State University Tallahassee FL 32306 USA
- National High Magnetic Field Laboratory Tallahassee FL 32310 USA
| | - Yijue Xu
- National High Magnetic Field Laboratory Tallahassee FL 32310 USA
| | - Christopher A O'Keefe
- Department of Chemistry & Biochemistry, University of Windsor Windsor ON N9B 3P4 Canada
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York Buffalo NY 14260-3000 USA
| | - Robert W Schurko
- Department of Chemistry & Biochemistry, Florida State University Tallahassee FL 32306 USA
- National High Magnetic Field Laboratory Tallahassee FL 32310 USA
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3
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Queen JD, Anderson-Sanchez LM, Stennett CR, Rajabi A, Ziller JW, Furche F, Evans WJ. Synthesis of Crystallographically Characterizable Bis(cyclopentadienyl) Sc(II) Complexes: (C 5H 2tBu 3) 2Sc and {[C 5H 3(SiMe 3) 2] 2ScI} 1. J Am Chem Soc 2024; 146:3279-3292. [PMID: 38264991 DOI: 10.1021/jacs.3c11922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
The synthesis of previously unknown bis(cyclopentadienyl) complexes of the first transition metal, i.e., Sc(II) scandocene complexes, has been investigated using C5H2(tBu)3 (Cpttt), C5Me5 (Cp*), and C5H3(SiMe3)2 (Cp″) ligands. Cpttt2ScI, 1, formed from ScI3 and KCpttt, can be reduced with potassium graphite (KC8) in hexanes to generate dark-red crystals of the first crystallographically characterizable bis(cyclopentadienyl) scandium(II) complex, Cpttt2Sc, 2. Complex 2 has a 170.6° (ring centroid)-Sc-(ring centroid) angle and exhibits an eight-line EPR spectrum characteristic of Sc(II) with Aiso = 82.6 MHz (29.6 G). It sublimes at 200 °C at 10-4 Torr and has a melting point of 268-271 °C. Reductions of Cp*2ScI and Cp″2ScI under analogous conditions in hexanes did not provide new Sc(II) complexes, and reduction of Cp*2ScI in benzene formed the Sc(III) phenyl complex, Cp*2Sc(C6H5), 3, by C-H bond activation. However, in Et2O and toluene, reduction of Cp*2ScI at -78 °C gives a dark-red solution, 4, which displays an eight-line EPR pattern like that of 1, but it did not provide thermally stable crystals. Reduction of Cp″2ScI, in THF or Et2O at -35 °C in the presence of 2.2.2-cryptand, yields the green Sc(II) metallocene iodide complex, [K(crypt)][Cp″2ScI], 5, which was identified by X-ray crystallography and EPR spectroscopy and is thermally unstable. The analogous reaction of Cp*2ScI with KC8 and 18-crown-6 in Et2O gave the ligand redistribution product, [Cp*2Sc(18-crown-6-κ2O,O')][Cp*2ScI2], 6, as the only crystalline product. Density functional theory calculations on the electronic structure of these compounds are reported in addition to a steric analysis using the Guzei method.
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Affiliation(s)
- Joshua D Queen
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | | | - Cary R Stennett
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Ahmadreza Rajabi
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Filipp Furche
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - William J Evans
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
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4
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Atterberry BA, Wimmer E, Estes DP, Rossini AJ. Acceleration of indirect detection 195Pt solid-state NMR experiments by sideband selective excitation or alternative indirect sampling schemes. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 352:107457. [PMID: 37163927 DOI: 10.1016/j.jmr.2023.107457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/27/2023] [Accepted: 04/12/2023] [Indexed: 05/12/2023]
Abstract
The measurement of the of chemical shift (CS) tensors via solid-state NMR (ssNMR) spectroscopy has proven to be a powerful probe of structure for organic molecules, biomolecules, and inorganic materials. However, when measuring the NMR spectra of heavy spin-1/2 isotopes the chemical shift anisotropy (CSA) is commonly on the order of thousands of parts per million, which makes acquisition of NMR spectra difficult due to the low NMR sensitivity imposed by the breadth of the signals and challenges in uniformly exciting the NMR spectrum. We have recently shown that complete 195Pt NMR spectra could be rapidly measured by using 195Pt saturation or excitation selective long pulses (SLP) with multiple rotor-cycle durations and RF fields less than 50 kHz into 1H{195Pt} or 1H-31P{195Pt} PE S-RESPDOR, TONE D-HMQC-4, J-resolved, and J-HMQC pulse sequences. The SLP only provide signal or dephasing when they are applied on resonance with a spinning sideband. The magic angle spinning 195Pt NMR spectrum is reconstructed in the sideband selective NMR experiments by acquiring 1D NMR spectra at variable 195Pt pulse offsets. In this work, we present a detailed investigation of the specific pulse conditions required for the ideal performance of sideband selective experiments. Sideband selective experiments are shown to be able to accurately reproduce MAS NMR spectra with minimal distortions of relative sideband intensities. It is also demonstrated that a 195Pt NMR spectrum indirectly detected with HMQC can be rapidly obtained by acquiring a single rotor cycle of indirect dimension evolution points. We dub this method One Rotor Cycle of Acquisition (ORCA) HMQC. Sideband selective experiments and ORCA HMQC experiments are shown to provide a one order of magnitude improvement in experiment times as compared to conventional wideline HMQC experiments.
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Affiliation(s)
- Benjamin A Atterberry
- US DOE Ames National Laboratory, Ames, IA 50011, USA; Iowa State University, Department of Chemistry, Ames, IA 50011, USA
| | - Erik Wimmer
- University of Stuttgart, Department of Chemistry, Stuttgart, Baden-Württemberg, 70569, Germany
| | - Deven P Estes
- University of Stuttgart, Department of Chemistry, Stuttgart, Baden-Württemberg, 70569, Germany
| | - Aaron J Rossini
- US DOE Ames National Laboratory, Ames, IA 50011, USA; Iowa State University, Department of Chemistry, Ames, IA 50011, USA.
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5
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Samudrala KK, Conley MP. Effects of surface acidity on the structure of organometallics supported on oxide surfaces. Chem Commun (Camb) 2023; 59:4115-4127. [PMID: 36912586 DOI: 10.1039/d3cc00047h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Well-defined organometallics supported on high surface area oxides are promising heterogeneous catalysts. An important design factor in these materials is how the metal interacts with the functionalities on an oxide support, commonly anionic X-type ligands derived from the reaction of an organometallic M-R with an -OH site on the oxide. The metal can either form a covalent M-O bond or form an electrostatic M+⋯-O ion-pair, which impacts how well-defined organometallics will interact with substrates in catalytic reactions. A less common reaction pathway involves the reaction of a Lewis site on the oxide with the organometallic, resulting in abstraction to form an ion-pair, which is relevant to industrial olefin polymerization catalysts. This Feature Article views the spectrum of reactivity between an organometallic and an oxide through the prism of Brønsted and/or Lewis acidity of surface sites and draws analogies to the molecular frame where Lewis and Brønsted acids are known to form reactive ion-pairs. Applications of the well-defined sites developed in this article are also discussed.
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Affiliation(s)
| | - Matthew P Conley
- Department of Chemistry, University of California, Riverside, California 92521, USA.
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6
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Venkatesh A, Gioffrè D, Atterberry BA, Rochlitz L, Carnahan SL, Wang Z, Menzildjian G, Lesage A, Copéret C, Rossini AJ. Molecular and Electronic Structure of Isolated Platinum Sites Enabled by the Expedient Measurement of 195Pt Chemical Shift Anisotropy. J Am Chem Soc 2022; 144:13511-13525. [PMID: 35861681 DOI: 10.1021/jacs.2c02300] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Techniques that can characterize the molecular structures of dilute surface species are required to facilitate the rational synthesis and improvement of Pt-based heterogeneous catalysts. 195Pt solid-state NMR spectroscopy could be an ideal tool for this task because 195Pt isotropic chemical shifts and chemical shift anisotropy (CSA) are highly sensitive probes of the local chemical environment and electronic structure. However, the characterization of Pt surface-sites is complicated by the typical low Pt loadings that are between 0.2 and 5 wt% and broadening of 195Pt solid-state NMR spectra by CSA. Here, we introduce a set of solid-state NMR methods that exploit fast MAS and indirect detection using a sensitive spy nucleus (1H or 31P) to enable the rapid acquisition of 195Pt MAS NMR spectra. We demonstrate that high-resolution wideline 195Pt MAS NMR spectra can be acquired in minutes to a few hours for a series of molecular and single-site Pt species grafted on silica with Pt loading of only 3-5 wt%. Low-power, long-duration, sideband-selective excitation, and saturation pulses are incorporated into t1-noise eliminated dipolar heteronuclear multiple quantum coherence, perfect echo resonance echo saturation pulse double resonance, or J-resolved pulse sequences. The complete 195Pt MAS NMR spectrum is then reconstructed by recording a series of 1D NMR spectra where the offset of the 195Pt pulses is varied in increments of the MAS frequency. Analysis of the 195Pt MAS NMR spectra yields the 195Pt chemical shift tensor parameters. Zeroth order approximation density functional theory calculations accurately predict 195Pt CS tensor parameters. Simple and predictive orbital models relate the CS tensor parameters to the Pt electronic structure and coordination environment. The methodology developed here paves the way for the detailed structural and electronic analysis of dilute platinum surface-sites.
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Affiliation(s)
- Amrit Venkatesh
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.,US DOE Ames Laboratory, Ames, Iowa 50011, United States
| | - Domenico Gioffrè
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Benjamin A Atterberry
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.,US DOE Ames Laboratory, Ames, Iowa 50011, United States
| | - Lukas Rochlitz
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Scott L Carnahan
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.,US DOE Ames Laboratory, Ames, Iowa 50011, United States
| | - Zhuoran Wang
- Univ Lyon, ENS Lyon, Université Lyon 1, CNRS, High-Field NMR Center of Lyon, UMR 5082, F-69100 Villeurbanne, France
| | - Georges Menzildjian
- Univ Lyon, ENS Lyon, Université Lyon 1, CNRS, High-Field NMR Center of Lyon, UMR 5082, F-69100 Villeurbanne, France
| | - Anne Lesage
- Univ Lyon, ENS Lyon, Université Lyon 1, CNRS, High-Field NMR Center of Lyon, UMR 5082, F-69100 Villeurbanne, France
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Aaron J Rossini
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.,US DOE Ames Laboratory, Ames, Iowa 50011, United States
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7
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Bekyarova E, Conley MP. The coordination chemistry of oxide and nanocarbon materials. Dalton Trans 2022; 51:8557-8570. [PMID: 35586978 DOI: 10.1039/d2dt00459c] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Understanding how a ligand affects the steric and electronic properties of a metal is the cornerstone of the inorganic chemistry enterprise. What happens when the ligand is an extended surface? This question is central to the design and implementation of state-of-the-art functional materials containing transition metals. This perspective will describe how these two very different sets of extended surfaces can form well-defined coordination complexes with metals. In the Green formalism, functionalities on oxide surfaces react with inorganics to form species that contain X-type or LX-type interactions between the metal and the oxide. Carbon surfaces are neutral L-type ligands; this perspective focuses on carbons that donate six electrons to a metal. The nature of this interaction depends on the curvature, and thereby orbital overlap, between the metal and the extended π-system from the nanocarbon.
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Affiliation(s)
- Elena Bekyarova
- Department of Chemistry, University of California, Riverside, California 92521, USA.
| | - Matthew P Conley
- Department of Chemistry, University of California, Riverside, California 92521, USA.
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8
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Huynh W, Taylor JW, Harman WH, Conley MP. Solid-state 11B NMR studies of coinage metal complexes containing a phosphine substituted diboraanthracene ligand. Dalton Trans 2021; 50:14855-14863. [PMID: 34604875 DOI: 10.1039/d1dt02981a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Transition metal interactions with Lewis acids (M → Z linkages) are fundamentally interesting and practically important. The most common Z-type ligands contain boron, which contains an NMR active 11B nucleus. We measured solid-state 11B{1H} NMR spectra of copper, silver, and gold complexes containing a phosphine substituted 9,10-diboraanthracene ligand (B2P2) that contain planar boron centers and weak M → BR3 linkages ([(B2P2)M][BArF4] (M = Cu (1), Ag (2), Au (3)) characterized by large quadrupolar coupling (CQ) values (4.4-4.7 MHz) and large span (Ω) values (93-139 ppm). However, the solid-state 11B{1H} NMR spectrum of K[Au(B2P2)]- (4), which contains tetrahedral borons, is narrow and characterized by small CQ and Ω values. DFT analysis of 1-4 shows that CQ and Ω are expected to be large for planar boron environments and small for tetrahedral boron, and that the presence of a M → BR3 linkage relates to the reduction in CQ and 11B NMR shielding properties. Thus solid-state 11B NMR spectroscopy contains valuable information about M → BR3 linkages in complexes containing the B2P2 ligand.
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Affiliation(s)
- Winn Huynh
- Department of Chemistry, University of California, Riverside, California 92521, USA.
| | - Jordan W Taylor
- Department of Chemistry, University of California, Riverside, California 92521, USA.
| | - W Hill Harman
- Department of Chemistry, University of California, Riverside, California 92521, USA.
| | - Matthew P Conley
- Department of Chemistry, University of California, Riverside, California 92521, USA.
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9
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Fan Z, Hu Y, Li H, Fu J, Fan Q, King RB, Schaefer HF. Agostic Hydrogens in 1‐Norbornyl Metal Cyclopentadienyl Structures. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Zhixiang Fan
- School of Science Key Laboratory of High Performance Scientific Computation Xihua University 610039 Chengdu China
| | - Yuchen Hu
- School of Science Key Laboratory of High Performance Scientific Computation Xihua University 610039 Chengdu China
| | - Huidong Li
- School of Science Key Laboratory of High Performance Scientific Computation Xihua University 610039 Chengdu China
- Department of Chemistry and Center for Computational Chemistry University of Georgia 30602 Athens Georgia USA
| | - Jia Fu
- School of Science Key Laboratory of High Performance Scientific Computation Xihua University 610039 Chengdu China
| | - Qunchao Fan
- School of Science Key Laboratory of High Performance Scientific Computation Xihua University 610039 Chengdu China
| | - R. Bruce King
- Department of Chemistry and Center for Computational Chemistry University of Georgia 30602 Athens Georgia USA
| | - Henry F. Schaefer
- Department of Chemistry and Center for Computational Chemistry University of Georgia 30602 Athens Georgia USA
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10
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Lin X, Wu W, Mo Y. A theoretical perspective of the agostic effect in early transition metal compounds. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213401] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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11
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Mortis A, Barisic D, Eichele K, Maichle-Mössmer C, Anwander R. Scandium bis(trimethylsilyl)methyl complexes revisited: extending the 45Sc NMR chemical shift range and a new structural motif of Li[CH(SiMe 3) 2]. Dalton Trans 2020; 49:7829-7841. [PMID: 32463406 DOI: 10.1039/d0dt01247e] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Depending on the molar ratio employed, the reaction of ScCl3(thf)3 with Li[CH(SiMe3)2] afforded the bis and tris(alkyl) ate complexes [Sc{CH(SiMe3)2}2(μ-Cl)2Li(thf)2]2 and Sc[CH(SiMe3)2]3(μ-Cl)Li(thf)3, respectively, in moderate yields. Treatment of these mixed alkyl/chlorido complexes with MeLi gave the mixed alkyl complexes [Sc{CH(SiMe3)2}2(μ-Me)2Li(thf)2]2 and Sc[CH(SiMe3)2]3(μ-Me)Li(thf)3. Aiming at homoleptic {Sc[CH(SiMe3)2]3} both of the mixed [CH(SiMe3)2]/Me complexes were treated with AlMe3. Although LiAlMe4 separation occurred, aluminium complex Al[CH(SiMe3)2]Me2(thf) was the only isolable crystalline complex. Ate complexes [Sc{CH(SiMe3)2}2(μ-Me)2Li(thf)2]2 and [Sc(CH2SiMe3)4][Li(thf)4] revealed the maximum downfield 45Sc NMR chemical shifts of 888.0 and 933.4 ppm, respectively, reported to date. The synthesis of putative {Sc[CH(SiMe3)2]3} was also attempted via the aryloxide route applying complexes Sc(OC6H2tBu2-2,6-Me-4)3 and [Sc(OC6H3iPr2-2,6)3]2 along with Li[CH(SiMe3)2] but the outcome was inconclusive. Instead, a cyclic octamer was found for Li[CH(SiMe3)2] in the solid state.
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Affiliation(s)
- Alexandros Mortis
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen, Germany.
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12
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Culver DB, Huynh W, Tafazolian H, Conley MP. Solid-State 45Sc NMR Studies of Cp* 2Sc–OR (R = CMe 2CF 3, CMe(CF 3) 2, C(CF 3) 3, SiPh 3) and Relationship to the Structure of Cp* 2Sc-Sites Supported on Partially Dehydroxylated Silica. Organometallics 2020. [DOI: 10.1021/acs.organomet.9b00840] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Damien B. Culver
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Winn Huynh
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Hosein Tafazolian
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Matthew P. Conley
- Department of Chemistry, University of California, Riverside, California 92521, United States
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13
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Chapovetsky A, Langeslay RR, Celik G, Perras FA, Pruski M, Ferrandon MS, Wegener EC, Kim H, Dogan F, Wen J, Khetrapal N, Sharma P, White J, Kropf AJ, Sattelberger AP, Kaphan DM, Delferro M. Activation of Low-Valent, Multiply M–M Bonded Group VI Dimers toward Catalytic Olefin Metathesis via Surface Organometallic Chemistry. Organometallics 2020. [DOI: 10.1021/acs.organomet.9b00787] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alon Chapovetsky
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Ryan R. Langeslay
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Gokhan Celik
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | | | - Marek Pruski
- U.S. DOE Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Magali S. Ferrandon
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Evan C. Wegener
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Hacksung Kim
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Center for Catalysis and Surface Science and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Fulya Dogan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Jianguo Wen
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Navneet Khetrapal
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Prachi Sharma
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jacob White
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - A. Jeremy Kropf
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Alfred P. Sattelberger
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - David M. Kaphan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Massimiliano Delferro
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Guo F, Tsoureas N, Huang G, Tong M, Mansikkamäki A, Layfield RA. Isolation of a Perfectly Linear Uranium(II) Metallocene. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201912663] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Fu‐Sheng Guo
- Department of ChemistryUniversity of Sussex Falmer, Brighton BN1 9QR UK
| | - Nikolaos Tsoureas
- Department of ChemistryUniversity of Sussex Falmer, Brighton BN1 9QR UK
| | - Guo‐Zhang Huang
- Key Laboratory of Bioinorganic and Synthetic Chemistry of the Ministry of EducationSchool of ChemistrySun Yat-Sen University Guangzhou 510275 P. R. China
| | - Ming‐Liang Tong
- Key Laboratory of Bioinorganic and Synthetic Chemistry of the Ministry of EducationSchool of ChemistrySun Yat-Sen University Guangzhou 510275 P. R. China
| | - Akseli Mansikkamäki
- Department of ChemistryNanoscience CenterUniversity of Jyväskylä P.O. Box 35 40014 Jyväskylä Finland
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15
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Guo FS, Tsoureas N, Huang GZ, Tong ML, Mansikkamäki A, Layfield RA. Isolation of a Perfectly Linear Uranium(II) Metallocene. Angew Chem Int Ed Engl 2020; 59:2299-2303. [PMID: 31710765 DOI: 10.1002/anie.201912663] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 10/21/2019] [Indexed: 11/11/2022]
Abstract
Reduction of the uranium(III) metallocene [(η5 -C5 i Pr5 )2 UI] (1) with potassium graphite produces the "second-generation" uranocene [(η5 -C5 i Pr5 )2 U] (2), which contains uranium in the formal divalent oxidation state. The geometry of 2 is that of a perfectly linear bis(cyclopentadienyl) sandwich complex, with the ground-state valence electron configuration of uranium(II) revealed by electronic spectroscopy and density functional theory to be 5f3 6d1 . Appreciable covalent contributions to the metal-ligand bonds were determined from a computational study of 2, including participation from the uranium 5f and 6d orbitals. Whereas three unpaired electrons in 2 occupy orbitals with essentially pure 5f character, the fourth electron resides in an orbital defined by strong 7s-6d z 2 mixing.
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Affiliation(s)
- Fu-Sheng Guo
- Department of Chemistry, University of Sussex, Falmer, Brighton, BN1 9QR, UK
| | - Nikolaos Tsoureas
- Department of Chemistry, University of Sussex, Falmer, Brighton, BN1 9QR, UK
| | - Guo-Zhang Huang
- Key Laboratory of Bioinorganic and Synthetic Chemistry of the Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Ming-Liang Tong
- Key Laboratory of Bioinorganic and Synthetic Chemistry of the Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Akseli Mansikkamäki
- Department of Chemistry, Nanoscience Center, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland
| | - Richard A Layfield
- Department of Chemistry, University of Sussex, Falmer, Brighton, BN1 9QR, UK
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16
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Huynh W, Conley MP. Origin of the 29Si NMR chemical shift in R3Si–X and relationship to the formation of silylium (R3Si+) ions. Dalton Trans 2020; 49:16453-16463. [DOI: 10.1039/d0dt02099k] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The origin in deshielding of 29Si NMR chemical shifts in R3Si–X, where X = H, OMe, Cl, OTf, [CH6B11X6], toluene, and OX (OX = surface oxygen), as well as iPr3Si+ and Mes3Si+ were studied using DFT methods.
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Affiliation(s)
- Winn Huynh
- Department of Chemistry
- University of California
- Riverside
- USA
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17
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Edelmann FT, Farnaby JH, Jaroschik F, Wilson B. Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2018. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.07.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Abstract
The hitherto unknown homoleptic tetramethylaluminate complex [Sc(AlMe4)3] could be obtained by reacting the ate complex [Li3ScMe6(thf)1.2] with AlMe3 in the cold. It cocrystallizes with AlMe3 as [Sc(AlMe4)3(Al2Me6)0.5] and decomposes at ambient temperature in n-pentane via multiple C-H bond activations to the mixed methyl/methylidene complex [Sc3(μ3-CH2)2(μ2-CH3)3(AlMe4)2(AlMe3)2]. Donor-induced methylaluminate cleavage of [Sc(AlMe4)3(Al2Me6)0.5] produced [ScMe3]n in good yield, which could be derivatized with trimethyltriazacyclononane (Me3TACN) to form the structurally characterizable [(Me3TACN)ScMe3]. Additionally, half-sandwich complex [Cp*Sc(AlMe4)2] and sandwich complex [Cp*2Sc(AlMe4)] were accessible by salt metathesis reactions from [Sc(AlMe4)3(Al2Me6)0.5] and KCp* (Cp* = C5Me5). 45Sc NMR spectroscopy was applied as a significant probe to evidence the existence of [ScMe3]n. Compounds [(Me3TACN)ScMe3] (+624.6 ppm) and [ScMe3(thf)x] (+601.7 ppm) gave large 45Sc NMR shifts, revealing the strong deshielding effect of the σ-bonded alkyl ligands on the scandium nuclei. Ultimately, cationized [Sc(AlMe4)3(Al2Me6)0.5] was employed in isoprene polymerization, leading to polymers in high yields (>95%) and with high (>90%) cis-1,4-polyisoprene content.
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Affiliation(s)
- Damir Barisic
- Institut für Anorganische Chemie , Eberhard Karls Universität Tübingen , Auf der Morgenstelle 18 , 72076 Tübingen , Germany
| | - Dominic Diether
- 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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19
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Xu P, Xu X. Dehydrogenation of (Di)amine–Boranes by Highly Active Scandocene Alkyl Catalysts. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00461] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pengfei Xu
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Xin Xu
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
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20
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Lin X, Wu W, Mo Y. Agostic Interactions in Early Transition-Metal Complexes: Roles of Hyperconjugation, Dispersion, and Steric Effect. Chemistry 2019; 25:6591-6599. [PMID: 30883975 DOI: 10.1002/chem.201900436] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/13/2019] [Indexed: 01/19/2023]
Abstract
The agostic interaction is a ubiquitous phenomenon in catalytic processes and transition-metal complexes, and hyperconjugation has been well recognized as its origin. Yet, recent studies showed that either short-range London dispersion or structural constraints could be the driving force, although proper evaluation of the role of hyperconjugation therein is needed. Herein, a simple variant of valence bond theory was employed to study a few exemplary Ti complexes with α- or β-agostic interactions and interpret the agostic effect in terms of the steric effect, hyperconjugation, and dispersion. For the complexes [MeTiCl3 (dmpe)] and [MeTiCl3 (dhpe)] with α-agostic interactions, hyperconjugation plays the dominant role with comparable magnitudes in both systems, but dispersion is solely responsible for the stronger agostic interaction in the former compared with the latter. For the complexes [EtTiCl3 (dmpe)] and [EtTiCl3 (dhpe)] with β-agostic interactions, however, hyperconjugation and dispersion play comparable roles, and the weaker steric repulsion leads to a stronger agostic effect in the former than in the latter. Thus, the present study clarifies the variable and sensitive roles of steric, hyperconjugative, and dispersion interactions in the agostic interaction.
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Affiliation(s)
- Xuhui Lin
- The State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and College of Chemistry and Chemical, Engineering, Xiamen University, Xiamen, Fujian, 361005, P.R. China
| | - Wei Wu
- The State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and College of Chemistry and Chemical, Engineering, Xiamen University, Xiamen, Fujian, 361005, P.R. China
| | - Yirong Mo
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, 49008, USA
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21
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Gordon CP, Culver DB, Conley MP, Eisenstein O, Andersen RA, Copéret C. π-Bond Character in Metal-Alkyl Compounds for C-H Activation: How, When, and Why? J Am Chem Soc 2019; 141:648-656. [PMID: 30525557 DOI: 10.1021/jacs.8b11951] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
C-H bond activation via σ-bond metathesis is typically observed with transition-metal alkyl compounds in d0 or d0fn electron configurations, e.g., biscyclopentadienyl metal alkyls. Related C-H activation processes are also observed for transition-metal alkyls with higher d-electron counts, such as W(II), Fe(II), or Ir(III). A σ-bond metathesis mechanism has been proposed in all cases with a preference for an oxidative addition-reductive elimination pathway for Ir(III). Herein we show that, regardless of the exact mechanism, C-H activation with all of these compounds is associated with π-character of the M-C bond, according to a detailed analysis of the 13C NMR chemical shift tensor of the α-carbon. π-Character is also a requirement for olefin insertion, indicating its similarity to σ-bond metathesis. This observation explains the H2 response observed in d0 olefin polymerization catalysts and underlines that σ-bond metathesis, olefin insertion, and olefin metathesis are in fact isolobal reactions.
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Affiliation(s)
- Christopher P Gordon
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1-5 , 8093 , Zürich , Switzerland
| | - Damien B Culver
- Department of Chemistry , University of California, Riverside , Riverside , California 92521 , United States
| | - Matthew P Conley
- Department of Chemistry , University of California, Riverside , Riverside , California 92521 , United States
| | - Odile Eisenstein
- Institut Charles Gerhardt, UMR 5253 CNRS-UM-ENSCM , Université de Montpellier , 34095 Montpellier , France.,Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry , University of Oslo , P.O. Box 1033, Blindern , 0315 Oslo , Norway
| | - Richard A Andersen
- Department of Chemistry , University of California , Berkeley , California 94720 , United States
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1-5 , 8093 , Zürich , Switzerland
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22
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Ehinger C, Gordon CP, Copéret C. Oxygen transfer in electrophilic epoxidation probed by 17O NMR: differentiating between oxidants and role of spectator metal oxo. Chem Sci 2018; 10:1786-1795. [PMID: 30842846 PMCID: PMC6369410 DOI: 10.1039/c8sc04868a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 11/30/2018] [Indexed: 11/21/2022] Open
Abstract
Peroxide compounds are used both in laboratory and industrial processes for the electrophilic epoxidation of olefins. Using NMR-spectroscopy, we investigate why certain peroxides engage in this type of reaction while others require activation by metal catalysts, e.g. methyltrioxorhenium (MTO). More precisely, an analysis of 17O NMR chemical shift and quadrupolar coupling parameters provides insights into the relative energy of specific frontier molecular orbitals relevant for reactivity. For organic peroxides or H2O2 a large deshielding is indicative of an energetically high-lying lone-pair on oxygen in combination with a low-lying σ*(O-O) orbital. This feature is particularly pronounced in species that engage in electrophilic epoxidation, such as peracids or dimethyldioxirane (DMDO), and much less pronounced in unreactive peroxides such as H2O2 and ROOH, which can however be activated by transition-metal catalysts. In fact, for the proposed active peroxo species in MTO-catalyzed electrophilic epoxidation with H2O2 an analysis of the 17O NMR chemical shift highlights specific π- and δ-type orbital interactions between the so-called metal spectator oxo and the peroxo moieties that raise the energy of the high-lying lone-pair on oxygen, thus increasing the reactivity of the peroxo species.
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Affiliation(s)
- Christian Ehinger
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1-5 , 8093 , Zürich , Switzerland .
| | - Christopher P Gordon
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1-5 , 8093 , Zürich , Switzerland .
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1-5 , 8093 , Zürich , Switzerland .
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23
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Huynh W, Culver DB, Tafazolian H, Conley MP. Solid-state 45Sc NMR studies of Cp*2Sc–X and Cp*2ScX(THF). Dalton Trans 2018; 47:13063-13071. [DOI: 10.1039/c8dt02623h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A systematic study showing how the Sc–X bond affects solid-state 45Sc NMR quadrupolar coupling constants in Cp*2Sc–X.
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Affiliation(s)
- Winn Huynh
- Department of Chemistry
- University of California
- Riverside
- USA
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