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O’Reilly ME, Ghiviriga I, Abboud KA, Veige AS. A New ONO3- Trianionic Pincer-Type Ligand for Generating Highly Nucleophilic Metal–Carbon Multiple Bonds. J Am Chem Soc 2012; 134:11185-95. [DOI: 10.1021/ja302222s] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthew E. O’Reilly
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville,
Florida 32611, United States
| | - Ion Ghiviriga
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville,
Florida 32611, United States
| | - Khalil A. Abboud
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville,
Florida 32611, United States
| | - Adam S. Veige
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville,
Florida 32611, United States
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Mills DP, Cooper OJ, Tuna F, McInnes EJL, Davies ES, McMaster J, Moro F, Lewis W, Blake AJ, Liddle ST. Synthesis of a uranium(VI)-carbene: reductive formation of uranyl(V)-methanides, oxidative preparation of a [R2C═U═O]2+ analogue of the [O═U═O]2+ uranyl ion (R = Ph2PNSiMe3), and comparison of the nature of U(IV)═C, U(V)═C, and U(VI)═C double bonds. J Am Chem Soc 2012; 134:10047-54. [PMID: 22621395 DOI: 10.1021/ja301333f] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We report attempts to prepare uranyl(VI)- and uranium(VI) carbenes utilizing deprotonation and oxidation strategies. Treatment of the uranyl(VI)-methanide complex [(BIPMH)UO(2)Cl(THF)] [1, BIPMH = HC(PPh(2)NSiMe(3))(2)] with benzyl-sodium did not afford a uranyl(VI)-carbene via deprotonation. Instead, one-electron reduction and isolation of di- and trinuclear [UO(2)(BIPMH)(μ-Cl)UO(μ-O){BIPMH}] (2) and [UO(μ-O)(BIPMH)(μ(3)-Cl){UO(μ-O)(BIPMH)}(2)] (3), respectively, with concomitant elimination of dibenzyl, was observed. Complexes 2 and 3 represent the first examples of organometallic uranyl(V), and 3 is notable for exhibiting rare cation-cation interactions between uranyl(VI) and uranyl(V) groups. In contrast, two-electron oxidation of the uranium(IV)-carbene [(BIPM)UCl(3)Li(THF)(2)] (4) by 4-morpholine N-oxide afforded the first uranium(VI)-carbene [(BIPM)UOCl(2)] (6). Complex 6 exhibits a trans-CUO linkage that represents a [R(2)C═U═O](2+) analogue of the uranyl ion. Notably, treatment of 4 with other oxidants such as Me(3)NO, C(5)H(5)NO, and TEMPO afforded 1 as the only isolable product. Computational studies of 4, the uranium(V)-carbene [(BIPM)UCl(2)I] (5), and 6 reveal polarized covalent U═C double bonds in each case whose nature is significantly affected by the oxidation state of uranium. Natural Bond Order analyses indicate that upon oxidation from uranium(IV) to (V) to (VI) the uranium contribution to the U═C σ-bond can increase from ca. 18 to 32% and within this component the orbital composition is dominated by 5f character. For the corresponding U═C π-components, the uranium contribution increases from ca. 18 to 26% but then decreases to ca. 24% and is again dominated by 5f contributions. The calculations suggest that as a function of increasing oxidation state of uranium the radial contraction of the valence 5f and 6d orbitals of uranium may outweigh the increased polarizing power of uranium in 6 compared to 5.
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Affiliation(s)
- David P Mills
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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53
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Mandal SK, Roesky HW. Group 14 hydrides with low valent elements for activation of small molecules. Acc Chem Res 2012; 45:298-307. [PMID: 21882810 DOI: 10.1021/ar2001759] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Transition metal compounds are well known as activators of small molecules, and they serve as efficient catalysts for a variety of homogeneous and heterogeneous transformations. In contrast, there is a general feeling that main group compounds cannot act as efficient catalysts because of their inability to activate small molecules. Traditionally, the activation of small molecules is considered one of the key steps during a catalytic cycle with transition metals. As a consequence, researchers have long neglected the full range of possibilities in harnessing main group elements for the design of efficient catalysts. Recent developments, however, have made it possible to synthesize main group compounds with low-valent elements capable of activating small molecules. In particular, the judicious use of sterically appropriate ligands has been successful in preparing and stabilizing a variety of Group 14 hydrides with low-valent elements. In this Account, we discuss recent advances in the synthesis of Group 14 hydrides with low-valent elements and assess their potential as small-molecule activators. Group 14, which comprises the nonmetal C, the semimetals Si and Ge, and the metals Sn and Pb, was for years a source of hydrides with the Group 14 element almost exclusively in tetravalent form. Synthetic difficulties and the low stability of Group 14 hydrides in lower oxidation states were difficult to overcome. But in 2000, a divalent Sn(II) hydride was prepared as a stable compound through the incorporation of sterically encumbered aromatic ligands. More recently, the stabilization of GeH(2) and SnH(2) complexes using an N-heterocyclic carbene (NHC) as a donor and BH(3) or a metal carbonyl complex as an acceptor was reported. A similar strategy was also employed to synthesize the Si(II) hydride. This class of hydrides may be considered coordinatively saturated, with the lone pair of electrons on the Group 14 elements taking part in coordination. We discuss the large-scale synthesis of hydrides of the form LMH (where M is Ge or Sn, L is CH(N(Ar)(CMe))(2), and Ar is 2,6-iPr(2)C(6)H(3)), which has made it possible to test their reactivity in the activation of small molecules. Unlike the tetravalent Group 14 hydrides, the Ge(II) and Sn(II) hydrides were found to be able to activate a number of small molecules in the absence of any externally added catalyst. For example, the Ge(II) hydride and Sn(II) hydride can activate CO(2), and the reaction results in the formation of Ge(II) and Sn(II) esters of formic acid. This product represents a prototype of a new class of compounds of Group 14 elements. Moreover, we examined the activation of carbonyl compounds, alkynes, diazo and azo compounds, azides, and compounds containing the C═N bond. These Group 14 hydrides with low-valent elements are shown to be able to activate a number of important small molecules with C≡C, C═O, N═N, and C═N bonds. The activation of small molecules is an important step forward in the realization of main group catalyst development. Although it is not yet customary to assay the potential of newly synthesized main group compounds for small-molecule activation, our results offer good reason to do so.
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Affiliation(s)
- Swadhin K. Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur-741252, India
| | - Herbert W. Roesky
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077, Göttingen, Germany
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Xue ZL, Morton LA. Transition metal alkylidene complexes. Pathways in their formation and tautomerization between bis-alkylidenes and alkyl alkylidynes. J Organomet Chem 2011. [DOI: 10.1016/j.jorganchem.2011.06.048] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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55
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Thomson RK, Monreal MJ, Masuda JD, Scott BL, Kiplinger JL. Lutetium gets a crown: Synthesis, structure and reaction chemistry of the separated ion pair complex, [Li(12-crown-4)2][(C5Me5)2LuMe2]. J Organomet Chem 2011. [DOI: 10.1016/j.jorganchem.2011.06.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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56
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Daniel J. Mindiola. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/anie.201100261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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57
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Daniel J. Mindiola. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201100261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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58
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Occhipinti G, Meermann C, Dietrich HM, Litlabø R, Auras F, Törnroos KW, Maichle-Mössmer C, Jensen VR, Anwander R. Synthesis and stability of homoleptic metal(III) tetramethylaluminates. J Am Chem Soc 2011; 133:6323-37. [PMID: 21466201 DOI: 10.1021/ja2001049] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Whereas a number of homoleptic metal(III) tetramethylaluminates M(AlMe(4))(3) of the rare earth metals have proven accessible, the stability of these compounds varies strongly among the metals, with some even escaping preparation altogether. The differences in stability may seem puzzling given that this class of metals usually is considered to be relatively uniform with respect to properties. On the basis of quantum chemically obtained relative energies and atomic and molecular descriptors of homoleptic tris(tetramethylaluminate) and related compounds of rare earth metals, transition metals, p-block metals, and actinides, multivariate modeling has identified the importance of ionic metal-methylaluminate bonding and small steric repulsion between the methylaluminate ligands for obtaining stable homoleptic compounds. Low electronegativity and a sufficiently large ionic radius are thus essential properties for the central metal atom. Whereas scandium and many transition metals are too small and too electronegative for this task, all lanthanides and actinides covered in this study are predicted to give homoleptic compounds stable toward loss of trimethylaluminum, the expected main decomposition reaction. Three of the predicted lanthanide-based compounds Ln(AlMe(4))(3) (Ln = Ce, Tm, Yb) have been prepared and fully characterized in the present work, in addition to Ln(OCH(2)tBu)(3)(AlMe(3))(3) (Ln = Sc, Nd) and [Eu(AlEt(4))(2)](n). At ambient temperature, donor-free hexane solutions of Ln(AlMe(4))(3) of the Ln(3+)/Ln(2+) redox-active metal centers display enhanced reduction to [Ln(AlMe(4))(2)](n) with decreasing negative redox potential, in the order Eu ≫ Yb ≫ Sm. Whereas Eu(AlMe(4))(3) could not be identified, Yb(AlMe(4))(3) turned out to be isolable in low yield. All attempts to prepare the putative Sc(AlMe(4))(3), featuring the smallest rare earth metal center, failed.
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Affiliation(s)
- Giovanni Occhipinti
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
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59
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Zhang WX, Wang Z, Nishiura M, Xi Z, Hou Z. Ln4(CH2)4 cubane-type rare-earth methylidene complexes consisting of "(C5Me4SiMe3)LnCH2" units (Ln = Tm, Lu). J Am Chem Soc 2011; 133:5712-5. [PMID: 21446751 DOI: 10.1021/ja200540b] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Tetranuclear cubane-type rare-earth methylidene complexes consisting of four "Cp'LnCH(2)" units, [Cp'Ln(μ(3)-CH(2))](4) (4-Ln; Ln = Tm, Lu; Cp' = C(5)Me(4)SiMe(3)), have been obtained for the first time through CH(4) elimination from the well-defined polymethyl complexes [Cp'Ln(μ(2)-CH(3))(2)](3) (2-Ln) or mixed methyl/methylidene precursors such as [Cp'(3)Ln(3)(μ(2)-Me)(3)(μ(3)-Me)(μ(3)-CH(2))] (3-Ln). The reaction of the methylidene complex 4-Lu with benzophenone leads to C═O bond cleavage and C═C bond formation to give the cubane-type oxo complex [Cp'Lu(μ(3)-O)](4) and CH(2)═CPh(2), while the methyl/methylidene complex 3-Tm undergoes sequential methylidene addition to the C═O group and ortho C-H activation of the two phenyl groups of benzophenone to afford the bis(benzo-1,2-diyl)ethoxy-chelated trinuclear complex [Cp'(3)Tm(3)(μ(2)-Me)(3){(C(6)H(4))(2)C(O)Me}] (6-Tm).
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Affiliation(s)
- Wen-Xiong Zhang
- Organometallic Chemistry Laboratory and Advanced Catalyst Research Team, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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60
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Liddle ST, Mills DP, Wooles AJ. Early metal bis(phosphorus-stabilised)carbene chemistry. Chem Soc Rev 2011; 40:2164-76. [PMID: 21321726 DOI: 10.1039/c0cs00135j] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Since the discovery of covalently-bound mid- and late-transition metal carbenes there has been a spectacular explosion of interest in their chemistry, but their early metal counterparts have lagged behind. In recent years, bis(phosphorus-stabilised)carbenes have emerged as valuable ligands for metals across the periodic table, and their use has in particular greatly expanded covalently-bound early metal carbene chemistry. In this tutorial review we introduce the reader to bis(phosphorus-stabilised)carbenes, and cover general preparative methods, structure and bonding features, and emerging reactivity studies of early metal derivatives (groups 1-4 and the f-elements).
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Affiliation(s)
- Stephen T Liddle
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
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61
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Mills DP, Soutar L, Lewis W, Blake AJ, Liddle ST. Regioselective C-H activation and sequential C-C and C-O bond formation reactions of aryl ketones promoted by an yttrium carbene. J Am Chem Soc 2011; 132:14379-81. [PMID: 20873758 DOI: 10.1021/ja107958u] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Rare earth carbenes exclusively exhibit Wittig-type reactivity with carbonyl compounds to afford alkenes. Here, we report that yttrium carbenes can effect regioselective ortho-C-H activation and sequential C-C and C-O bond formation reactions of aryl ketones to give iso-benzofurans and hydroxymethylbenzophenones. With MeCOPh, cyclotetramerization occurs giving a substituted cyclohexene. This demonstrates new rare earth carbene reactivity which complements existing Wittig-type reactivity.
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Affiliation(s)
- David P Mills
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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62
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Hong J, Zhang L, Yu X, Li M, Zhang Z, Zheng P, Nishiura M, Hou Z, Zhou X. Syntheses, Structures, and Reactivities of Homometallic Rare-Earth-Metal Multimethyl Methylidene and Oxo Complexes. Chemistry 2011; 17:2130-7. [DOI: 10.1002/chem.201002670] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Indexed: 11/10/2022]
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63
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Herndon JW. The chemistry of the carbon–transition metal double and triple bond: Annual survey covering the year 2009. Coord Chem Rev 2011. [DOI: 10.1016/j.ccr.2010.07.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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64
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Al-Rafia SMI, Malcolm AC, Liew SK, Ferguson MJ, Rivard E. Stabilization of the Heavy Methylene Analogues, GeH2 and SnH2, within the Coordination Sphere of a Transition Metal. J Am Chem Soc 2010; 133:777-9. [DOI: 10.1021/ja1106223] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- S. M. Ibrahim Al-Rafia
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2
| | - Adam C. Malcolm
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2
| | - Sean K. Liew
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2
| | - Michael J. Ferguson
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2
| | - Eric Rivard
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2
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65
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Huang W, Carver CT, Diaconescu PL. Transmetalation Reactions of a Scandium Complex Supported by a Ferrocene Diamide Ligand. Inorg Chem 2010; 50:978-84. [DOI: 10.1021/ic1016005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wenliang Huang
- Department of Chemistry & Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Colin T. Carver
- Department of Chemistry & Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Paula L. Diaconescu
- Department of Chemistry & Biochemistry, University of California, Los Angeles, California 90095, United States
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67
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Johnson KRD, Hayes PG. Kinetic and Mechanistic Investigation of Metallacycle Ring Opening in an Ortho-Metalated Lutetium Aryl Complex. Organometallics 2010. [DOI: 10.1021/om100814h] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kevin R. D. Johnson
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, Canada T1K 3M4
| | - Paul G. Hayes
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, Canada T1K 3M4
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68
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Dang L, Lin Z, Marder TB. DFT Studies on the Carboxylation of Arylboronate Esters with CO2 Catalyzed by Copper(I) Complexes. Organometallics 2010. [DOI: 10.1021/om901047e] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Li Dang
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China
| | - Zhenyang Lin
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China
| | - Todd B. Marder
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
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69
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Zimmermann M, Rauschmaier D, Eichele K, Törnroos KW, Anwander R. Amido-stabilized rare-earth metal mixed methyl methylidene complexes. Chem Commun (Camb) 2010; 46:5346-8. [DOI: 10.1039/c003206a] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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70
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Schmitt AL, Schnee G, Welter R, Dagorne S. Unusual reactivity in organoaluminium and NHC chemistry: deprotonation of AlMe3 by an NHC moiety involving the formation of a sterically bulky NHC–AlMe3 Lewis adduct. Chem Commun (Camb) 2010; 46:2480-2. [DOI: 10.1039/b922425d] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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