1
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Neururer F, Huter K, Seidl M, Hohloch S. Reactivity and Structure of a Bis-phenolate Niobium NHC Complex. ACS ORGANIC & INORGANIC AU 2022; 3:59-71. [PMID: 36748079 PMCID: PMC9896488 DOI: 10.1021/acsorginorgau.2c00028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022]
Abstract
We report the facile synthesis of a rare niobium(V) imido NHC complex with a dianionic OCO-pincer benzimidazolylidene ligand (L 1 ) with the general formula [NbL 1 (N t Bu)PyCl] 1-Py. We achieved this by in situ deprotonation of the corresponding azolium salt [H 3 L 1 ][Cl] and subsequent reaction with [Nb(N t Bu)Py 2 Cl 3 ]. The pyridine ligand in 1-Py can be removed by the addition of B(C6F5)3 as a strong Lewis acid leading to the formation of the pyridine-free complex 1. In contrast to similar vanadium(V) complexes, complex 1-Py was found to be a good precursor for various salt metathesis reactions, yielding a series of chalcogenido and pnictogenido complexes with the general formula [ NbL 1 (N t Bu)Py(EMes)] (E = O (2), S (3), NH (4), and PH (5)). Furthermore, complex 1-Py can be converted to alkyl complex (6) with 1 equiv of neosilyl lithium as a transmetallation agent. Addition of a second equivalent yields a new trianionic supporting ligand on the niobium center (7) in which the benzimidazolylidene ligand is alkylated at the former carbene carbon atom. The latter is an interesting chemically "noninnocent" feature of the benzimidazolylidene ligand potentially useful in catalysis and atom transfer reactions. Addition of mesityl lithium to 1-Py gives the pyridine-free aryl complex 8, which is stable toward "overarylation" by an additional equivalent of mesityl lithium. Electrochemical investigation revealed that complexes 1-Py and 1 are inert toward reduction in dichloromethane but show two irreversible reduction processes in tetrahydrofuran as a solvent. However, using standard reduction agents, e.g., KC8, K-mirror, and Na/Napht, no reduced products could be isolated. All complexes have been thoroughly studied by various techniques, including 1H-, 13C{1H}-, and 1H-15N HMBC NMR spectroscopy, IR spectroscopy, and X-ray diffraction analysis.
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2
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Ouellette ET, Magdalenski JS, Bergman RG, Arnold J. Applications of Low-Valent Transition Metalates: Development of a Reactive Noncarbonyl Rhenium(I) Anion. Acc Chem Res 2022; 55:783-793. [PMID: 35171568 DOI: 10.1021/acs.accounts.2c00013] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Low-valent transition metalates─anionic, electronic-rich organometallic complexes─comprise a class of highly reactive chemical reagents that find integral applications in organic synthesis, small-molecule activation, transient species stabilization, and M-E bond formation, among others. The inherent reactivity of such electron-rich metal centers has necessitated the widespread use of strong backbonding ligands, particularly carbonyls, to aid in the isolation and handling of metalate reagents, albeit sometimes at the expense of partially masking their full reactivity. However, recent synthetic explorations into transition-metalate complexes devoid of archetypic back-bonding ligands have led to the discovery of highly reactive metalates capable of performing a variety of novel chemical transformations.Building on our group's long-standing interest in reactive organometallic species, a series of rational progressions in early-to-middle transition-metal chemistry ultimately led to our isolation of a rhenium(I) β-diketiminate cyclopentadienide metalate that displays exceptional reactivity. We have found this Re(I) metalate to be capable of small-molecule activation; notably, the complex reversibly binds dinitrogen in solution and can be utilized to trap N2 for the synthesis of functionalized diazenido species. By employing isolobal analogues to N2 (CO and RNC), we were able to thoroughly monitor the mechanism of activation and conclude that the metalate's sodium counterion plays an integral role in promoting dinitrogen activation through a novel side-on interaction. The Re(I) metalate is also used in forming a variety of M-E bonds, including a series of uncommon rhenium-tetrylene (Si, Ge, and Sn) complexes that display varying degrees of multiple bonding. These metal tetrylenes act to highlight deviations in chemical properties within the group 14 elements. Our metalate's utility also applies to metal-metal bond formation, as demonstrated through the synthesis of a heterotetrametallic rhenium-zinc dimer. In this reaction, the Re(I) metalate performs a dual role as a reductant and metalloligand to stabilize a transient Zn22+ core fragment. Finally, the metalate displays unique reactivity with uranium(III) to yield the first transition metal-actinide inverse-sandwich bonds, in this case with three rhenium fragments bound through their Cp moieties surrounding the uranium center. Notably, throughout these endeavors we demonstrate that the metalate displays reactivity at multiple locations, including directly at the rhenium metal center, at a Cp carbon, through a Cp-sandwich mode, or through reversibly bound dinitrogen.Overall, the rhenium(I) metalate described herein demonstrates utility in diverse applications: small-molecule activation, the stabilization of reduced and/or unstable species, and the formation of unconventional M-E/M-M bonds or heterometallic complexes. Moving forward, we suggest that the continued discovery of noncarbonyl, electron-rich transition-metal anions featuring new or unconventional ligands should produce additional reactive organometallic species capable of stabilizing unique structural motifs and performing novel and unusual chemical transformations.
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Affiliation(s)
- Erik T. Ouellette
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Julian S. Magdalenski
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert G. Bergman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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3
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Fostvedt JI, Boreen MA, Bergman RG, Arnold J. A Diverse Array of C-C Bonds Formed at a Tantalum Metal Center. Inorg Chem 2021; 60:9912-9931. [PMID: 34125521 DOI: 10.1021/acs.inorgchem.1c01159] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We demonstrate the formation of a diverse array of organic and organometallic products containing newly formed C-C bonds via successive methyl transfers from di-, tri-, and tetramethyl Ta(V) precursors to unsaturated small molecule substrates under mild conditions. The reactions of Ta(V) methyl complexes 1-X [H2B(MesIm)2]TaMe3X (X = Me, Cl; Im = imidazole, Mes = 2,4,6-trimethylphenyl) with CO led to oxo enolate Ta(V) products, in which the enolate ligands were constructed from Ta-Me groups and two equivalents of CO. Similarly, the reaction of 1-Me with CNXyl yielded an imido enamine Ta(V) product. Surprisingly, 1-Cl reacted with CNXyl (1 equiv) at the borate backbone of the [H2B(MesIm)2] ligand with concomitant methyl transfer from the metal center to form a new, dianionic scorpionate ligand that supported a Ta(V) dimethyl chloro complex (6). Treatment of 1-Cl with further CNXyl led to an azaallyl scorpionate complex, and an imido isocyanide scorpionate complex, along with propene and xylyl ketenimine. Complex 6 reacted with CO to yield a pinacol scorpionate complex 10-a new reaction pathway in early transition metal chemistry. Mechanistic studies revealed that this proceeded via migratory insertion of CO into a Ta-Me group, followed by methyl transfer to form an η2-acetone intermediate. Elimination of acetone furnished a CO-stabilized Ta(III) intermediate capable of rebinding and subsequently coupling two equivalents of CO-derived acetone to form the pinacol ligand in 10.
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Affiliation(s)
- Jade I Fostvedt
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Michael A Boreen
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert G Bergman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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4
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Fostvedt JI, Grant LN, Kriegel BM, Obenhuber AH, Lohrey TD, Bergman RG, Arnold J. 1,2-Addition and cycloaddition reactions of niobium bis(imido) and oxo imido complexes. Chem Sci 2020; 11:11613-11632. [PMID: 34094408 PMCID: PMC8162998 DOI: 10.1039/d0sc03489d] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 09/28/2020] [Indexed: 11/21/2022] Open
Abstract
The bis(imido) complexes (BDI)Nb(N t Bu)2 and (BDI)Nb(N t Bu)(NAr) (BDI = N,N'-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate; Ar = 2,6-diisopropylphenyl) were shown to engage in 1,2-addition and [2 + 2] cycloaddition reactions with a wide variety of substrates. Reaction of the bis(imido) complexes with dihydrogen, silanes, and boranes yielded hydrido-amido-imido complexes via 1,2-addition across Nb-imido π-bonds; some of these complexes were shown to further react via insertion of carbon dioxide to give formate-amido-imido products. Similarly, reaction of (BDI)Nb(N t Bu)2 with tert-butylacetylene yielded an acetylide-amido-imido complex. In contrast to these results, many related mono(imido) Nb BDI complexes do not exhibit 1,2-addition reactivity, suggesting that π-loading plays an important role in activating the Nb-N π-bonds toward addition. The same bis(imido) complexes were also shown to engage in [2 + 2] cycloaddition reactions with oxygen- and sulfur-containing heteroallenes to give carbamate- and thiocarbamate-imido complexes: some of these complexes readily dimerized to give bis-μ-sulfido, bis-μ-iminodicarboxylate, and bis-μ-carbonate complexes. The mononuclear carbamate imido complex (BDI)Nb(NAr)(N( t Bu)CO2) (12) could be induced to eject tert-butylisocyanate to generate a four-coordinate terminal oxo imido intermediate, which could be trapped as the five-coordinate pyridine or DMAP adduct. The DMAP adducted oxo imido complex (BDI)NbO(NAr)(DMAP) (16) was shown to engage in 1,2-addition of silanes across the Nb-oxo π-bond; this represents a new reaction pathway in group 5 chemistry.
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Affiliation(s)
- Jade I Fostvedt
- Department of Chemistry, University of California Berkeley CA 94720 USA
| | - Lauren N Grant
- Department of Chemistry, University of California Berkeley CA 94720 USA
| | | | | | - Trevor D Lohrey
- Department of Chemistry, University of California Berkeley CA 94720 USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94720 USA
| | - Robert G Bergman
- Department of Chemistry, University of California Berkeley CA 94720 USA
| | - John Arnold
- Department of Chemistry, University of California Berkeley CA 94720 USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94720 USA
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5
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Lohrey TD, Cortes EA, Fostvedt JI, Oanta AK, Jain A, Bergman RG, Arnold J. Diverse Reactivity of a Rhenium(V) Oxo Imido Complex: [2 + 2] Cycloadditions, Chalcogen Metathesis, Oxygen Atom Transfer, and Protic and Hydridic 1,2-Additions. Inorg Chem 2020; 59:11096-11107. [DOI: 10.1021/acs.inorgchem.0c01589] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Trevor D. Lohrey
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Emmanuel A. Cortes
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Jade I. Fostvedt
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Alexander K. Oanta
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Anukta Jain
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert G. Bergman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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6
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Ziegler JA, Prange C, Lohrey TD, Bergman RG, Arnold J. Hydroboration Reactivity of Niobium Bis(N-heterocyclic carbene)borate Complexes. Inorg Chem 2018; 57:5213-5224. [DOI: 10.1021/acs.inorgchem.8b00247] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Jessica A. Ziegler
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Céline Prange
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule Zürich, Zürich CH-8093, Switzerland
| | - Trevor D. Lohrey
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert G. Bergman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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7
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Kriegel BM, Kaltsoyannis N, Chatterjee R, Bergman RG, Arnold J. Synthesis and Redox Chemistry of a Tantalum Alkylidene Complex Bearing a Metallaimidazole Ring. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00448] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Benjamin M. Kriegel
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Nikolas Kaltsoyannis
- School
of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Ruchira Chatterjee
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Robert G. Bergman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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8
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Kriegel BM, Naested LCE, Nocton G, Lakshmi KV, Lohrey TD, Bergman RG, Arnold J. Redox-Initiated Reactivity of Dinuclear β-Diketiminatoniobium Imido Complexes. Inorg Chem 2017; 56:1626-1637. [PMID: 28098983 DOI: 10.1021/acs.inorgchem.6b02735] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High-valent dichloride and dimethylniobium complexes 1 and 2 bearing tert-butylimido and N,N'-bis(2,4,6-trimethylphenyl)-β-diketiminate (BDIAr) ligands were prepared. The dimethyl complex reacted with dihydrogen to release methane and generate the hydride-bridged diniobium(IV) complex 3 in high yield. One-electron oxidation of 3 with silver salts resulted in the release of dihydrogen and conversion to a mixed-valent NbIII-NbIV complex, 4, that displayed a frozen-solution X-band electron paramagnetic resonance signal consistent with a slight dissymmetry between the two Nb centers. Spectroscopic and computational analysis supported the presence of Nb-Nb σ-bonding interactions in both 3 and 4. Finally, one-electron reduction of 4 resulted in conversion to the highly dissymmetric NbV-NbV dimer 5 that formed from the reductive C-N bond cleavage of one of the BDIAr supporting ligands.
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Affiliation(s)
- Benjamin M Kriegel
- Department of Chemistry, University of California , Berkeley, California 94720, United States
| | - Lara C E Naested
- Department of Chemistry, University of California , Berkeley, California 94720, United States.,Ecole Polytechnique Fédérale de Lausanne, Institut des Sciences et Ingénierie Chimiques , CH-1015 Lausanne, Switzerland
| | - Grégory Nocton
- LCM, CNRS, Ecole Polytechnique, Université Paris-Saclay , Route de Saclay, 91128 Palaiseau Cedex, France
| | - K V Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Trevor D Lohrey
- Department of Chemistry, University of California , Berkeley, California 94720, United States
| | - Robert G Bergman
- Department of Chemistry, University of California , Berkeley, California 94720, United States
| | - John Arnold
- Department of Chemistry, University of California , Berkeley, California 94720, United States
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9
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10
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Hohloch S, Kriegel BM, Bergman RG, Arnold J. Group 5 chemistry supported by β-diketiminate ligands. Dalton Trans 2016; 45:15725-15745. [DOI: 10.1039/c6dt01770c] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
β-Diketiminate (BDI) ligands are widely used supporting ligands in modern organometallic chemistry and are capable of stabilizing various metal complexes in multiple oxidation states and coordination environments.
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Affiliation(s)
| | | | | | - John Arnold
- Department of Chemistry
- University of California
- Berkeley
- USA
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11
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Camp C, Arnold J. On the non-innocence of “Nacnacs”: ligand-based reactivity in β-diketiminate supported coordination compounds. Dalton Trans 2016; 45:14462-98. [DOI: 10.1039/c6dt02013e] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
While β-diketiminate (BDI or ‘nacnac’) ligands have been widely adopted to stabilize a wide range of metal ions in multiple oxidation states and coordination numbers, in several occurrences these ligands do not behave as spectators and participate in reactivity.
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Affiliation(s)
- Clément Camp
- Univ Lyon
- CNRS, ESCPE Lyon
- Université Claude Bernard Lyon 1
- C2P2 UMR 5265
- F-69616 Villeurbanne
| | - John Arnold
- Department of Chemistry
- University of California
- Berkeley
- USA
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12
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Kriegel BM, Bergman RG, Arnold J. Nitrene Metathesis and Catalytic Nitrene Transfer Promoted by Niobium Bis(imido) Complexes. J Am Chem Soc 2015; 138:52-5. [DOI: 10.1021/jacs.5b11287] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Benjamin M. Kriegel
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert G. Bergman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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13
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Sietzen M, Wadepohl H, Ballmann J. Synthesis and reactivity of cyclometalated triamidophosphine complexes of niobium and tantalum. Inorg Chem 2015; 54:4094-103. [PMID: 25856693 DOI: 10.1021/acs.inorgchem.5b00333] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The triamidophosphine protioligand 1 reacts with the homoleptic pentakis(dimethylamido) precursors of niobium and tantalum [M(NMe2)5, where M = Nb, Ta] to form cyclometalated complexes of the type [N2PCN-κ(5)-N,N,P,C,N]M(NMe2) (2-M). Apart from the three amido donors, one benzylic position of the ligand backbone is deprotonated over the course of this reaction, resulting in the formation of a new M-C bond. As a consequence, a metallaziridine substructure is formed, and the triamidophosphine moiety thus serves as a tetraanionic pentadentate ligand. The dimethylamido complexes 2-M can be converted into the corresponding triflates [N2PCN-κ(5)-N,N,P,C,N]M(OTf) (3-M) and alkyl complexes [N2PCN-κ(5)-N,N,P,C,N]M(CH2SiMe3) (4-M) by treatment with triethylsilyl triflate (Et3SiO3SCF3) followed by (trimethylsilyl)methyllithium (LiCH2SiMe3). The alkyl complexes exhibit interesting reactivities, including a second cyclometalative backbone activation affording the trimethylphosphine-stabilized complexes [NP(CN)2-κ(6)-N,P,C,N,C,N]M(PMe3) (5-M). In the case of tantalum, the formation of a dinuclear hydrido complex (6) is observed upon hydrogenation of 4-Ta. In the case of niobium, the metallaziridine substructure in 4-Nb is prone to ring opening via protonation with triphenylsilylamine (Ph3SiNH2), resulting in formation of the corresponding imido complex [PN3-κ(4)-P,N,N,N]Nb=NSiPh3 (7).
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Affiliation(s)
- Malte Sietzen
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
| | - Joachim Ballmann
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
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14
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Gianetti TL, Bergman RG, Arnold J. Stoichiometric carbon–carbon bond formation mediated by well defined Nb(III) complexes. Polyhedron 2014. [DOI: 10.1016/j.poly.2014.05.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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15
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Gianetti TL, Nocton G, Minasian SG, Kaltsoyannis N, Kilcoyne ALD, Kozimor SA, Shuh DK, Tyliszczak T, Bergman RG, Arnold J. Electron localization in a mixed-valence diniobium benzene complex. Chem Sci 2014; 6:993-1003. [PMID: 29560186 PMCID: PMC5811154 DOI: 10.1039/c4sc02705a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/17/2014] [Indexed: 01/08/2023] Open
Abstract
One electron oxidation of a neutral diniobium benzene complex leads to a mixed-valence species. Single crystal X-ray diffraction, EPR, L3,2-edge XANES, and DFT indicate that the unpaired electron is localized on one metal center.
Reaction of the neutral diniobium benzene complex {[Nb(BDI)NtBu]2(μ-C6H6)} (BDI = N,N′-diisopropylbenzene-β-diketiminate) with Ag[B(C6F5)4] results in a single electron oxidation to produce a cationic diniobium arene complex, {[Nb(BDI)NtBu]2(μ-C6H6)}{B(C6F5)4}. Investigation of the solid state and solution phase structure using single-crystal X-ray diffraction, cyclic voltammetry, magnetic susceptibility, and multinuclear NMR spectroscopy indicates that the oxidation results in an asymmetric molecule with two chemically inequivalent Nb atoms. Further characterization using density functional theory (DFT) calculations, UV-visible, Nb L3,2-edge X-ray absorption near-edge structure (XANES), and EPR spectroscopies supports assignment of a diniobium complex, in which one Nb atom carries a single unpaired electron that is not largely delocalized on the second Nb atom. During the oxidative transformation, one electron is removed from the δ-bonding HOMO, which causes a destabilization of the molecule and formation of an asymmetric product. Subsequent reactivity studies indicate that the oxidized product allows access to metal-based chemistry with substrates that did not exhibit reactivity with the starting neutral complex.
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Affiliation(s)
- Thomas L Gianetti
- Department of Chemistry , University of California , Berkeley , CA 94720 , USA . ;
| | - Grégory Nocton
- Laboratoire de Chimie Moléculaire , CNRS , Ecole Polytechnique , 91128 Palaiseau , France .
| | - Stefan G Minasian
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA.,Chemistry Division , Los Alamos National Laboratory , Los Alamos , NM 87545 , USA
| | - Nikolas Kaltsoyannis
- Department of Chemistry , University College London , 20 Gordon Street , London , WC1H0AJ , UK .
| | - A L David Kilcoyne
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA
| | - Stosh A Kozimor
- Chemistry Division , Los Alamos National Laboratory , Los Alamos , NM 87545 , USA
| | - David K Shuh
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA
| | - Tolek Tyliszczak
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA
| | - Robert G Bergman
- Department of Chemistry , University of California , Berkeley , CA 94720 , USA . ;
| | - John Arnold
- Department of Chemistry , University of California , Berkeley , CA 94720 , USA . ;
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16
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Synthesis and characterization of group 5 imido complexes supported by the 2,6-dichloroaryl β-diketiminato ligand. Inorganica Chim Acta 2014. [DOI: 10.1016/j.ica.2014.07.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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17
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Kriegel BM, Bergman RG, Arnold J. Generation of low-valent tantalum species by reversible C–H activation in a cyclometallated tantalum hydride complex. Dalton Trans 2014; 43:10046-56. [DOI: 10.1039/c4dt00923a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Gianetti TL, Bergman RG, Arnold J. Carbon–fluorine bond cleavage in fluoroarenes via a niobium(iii) imido complex: from stoichiometric to catalytic hydrodefluorination. Chem Sci 2014. [DOI: 10.1039/c4sc00006d] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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19
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La Pierre HS, Minasian SG, Abubekerov M, Kozimor SA, Shuh DK, Tyliszczak T, Arnold J, Bergman RG, Toste FD. Vanadium Bisimide Bonding Investigated by X-ray Crystallography, 51V and 13C Nuclear Magnetic Resonance Spectroscopy, and V L3,2-Edge X-ray Absorption Near-Edge Structure Spectroscopy. Inorg Chem 2013; 52:11650-60. [DOI: 10.1021/ic4020543] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Henry S. La Pierre
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - Stefan G. Minasian
- Inorganic,
Isotope and Actinide Chemistry, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- Chemical
Sciences Division and Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Mark Abubekerov
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - Stosh A. Kozimor
- Inorganic,
Isotope and Actinide Chemistry, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - David K. Shuh
- Chemical
Sciences Division and Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Tolek Tyliszczak
- Chemical
Sciences Division and Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - John Arnold
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - Robert G. Bergman
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - F. Dean Toste
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
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20
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Gianetti TL, La Pierre HS, Arnold J. Group 5 Imides and Bis(imide)s as Selective Hydrogenation Catalysts. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201300202] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Gianetti TL, Nocton G, Minasian SG, Tomson NC, Kilcoyne ALD, Kozimor SA, Shuh DK, Tyliszczak T, Bergman RG, Arnold J. Diniobium Inverted Sandwich Complexes with μ-η6:η6-Arene Ligands: Synthesis, Kinetics of Formation, and Electronic Structure. J Am Chem Soc 2013; 135:3224-36. [DOI: 10.1021/ja311966h] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Thomas L. Gianetti
- Department of Chemistry, University of California, Berkeley, California 94720,
United States
| | - Grégory Nocton
- Department of Chemistry, University of California, Berkeley, California 94720,
United States
- Laboratoire
Hétéroéléments
et Coordination, UMR CNRS 7653, Ecole Polytechnique, 91128 Palaiseau, France
| | - Stefan G. Minasian
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico
87545, United States
| | - Neil C. Tomson
- Department of Chemistry, University of California, Berkeley, California 94720,
United States
| | | | - Stosh A. Kozimor
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico
87545, United States
| | | | | | - Robert G. Bergman
- Department of Chemistry, University of California, Berkeley, California 94720,
United States
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720,
United States
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22
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Phillips AD, Thommes K, Scopelliti R, Gandolfi C, Albrecht M, Severin K, Schreiber DF, Dyson PJ. Modulating the Steric, Electronic, and Catalytic Properties of Cp* Ruthenium Half-Sandwich Complexes with β-Diketiminato Ligands. Organometallics 2011. [DOI: 10.1021/om2006479] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrew D. Phillips
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- School
of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Katrin Thommes
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Rosario Scopelliti
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Claudio Gandolfi
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg,
Switzerland
| | - Martin Albrecht
- School
of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg,
Switzerland
| | - Kay Severin
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Dominique F. Schreiber
- School
of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Paul J. Dyson
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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23
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Gianetti TL, Tomson NC, Arnold J, Bergman RG. Z-selective, catalytic internal alkyne semihydrogenation under H2/CO mixtures by a niobium(III) imido complex. J Am Chem Soc 2011; 133:14904-7. [PMID: 21854008 DOI: 10.1021/ja206016s] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The discovery of a Nb(III)-mediated catalytic hydrogenation of internal alkynes to (Z)-alkenes that proceeds through an unprecedented mechanism is reported. The mechanistic proposal involves initial reduction of the alkyne by the Nb(III) complex (BDI)Nb(N(t)Bu)(CO)(2) to provide a Nb(V) metallacyclopropene, itself capable of σ-bond metathesis reactivity with H(2). The resulting alkenyl hydride species then undergoes reductive elimination to provide the (Z)-alkene product and regenerate a metal complex in the Nb(III) oxidation state. Support for the proposed mechanism is derived from (i) the dependence of the product selectivity on the relative concentrations of CO and H(2), (ii) the isolation of complexes closely related to those proposed to be part of the catalytic cycle, (iii) H/D crossover experiments, and (iv) DFT studies of multiple possible reaction pathways.
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Affiliation(s)
- Thomas L Gianetti
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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24
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Reactivity studies of a pseudo three-coordinate vanadium(II) complex: Synthesis of terminal oxo and sulfido complexes of vanadium(IV) and S–S and Se–Se reductive bond cleavage reactions. Inorganica Chim Acta 2011. [DOI: 10.1016/j.ica.2010.11.040] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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25
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Pizzetti M, Russo A, Petricci E. Microwave‐Assisted Aminocarbonylation of Ynamides by Using Catalytic [Fe
3
(CO)
12
] at Low Pressures of Carbon Monoxide. Chemistry 2011; 17:4523-8. [DOI: 10.1002/chem.201100447] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Indexed: 11/07/2022]
Affiliation(s)
- Marianna Pizzetti
- Dipartimento Farmaco Chimico Tecnologico, Università degli Studi di Siena, Via A. Moro, 53100 Siena (Italy), Fax: (+39) 0577‐2343‐33
| | - Adele Russo
- Dipartimento Farmaco Chimico Tecnologico, Università degli Studi di Siena, Via A. Moro, 53100 Siena (Italy), Fax: (+39) 0577‐2343‐33
| | - Elena Petricci
- Dipartimento Farmaco Chimico Tecnologico, Università degli Studi di Siena, Via A. Moro, 53100 Siena (Italy), Fax: (+39) 0577‐2343‐33
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26
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Tomson NC, Arnold J, Bergman RG. Synthesis and reactivity of cationic niobium and tantalum methyl complexes supported by imido and β-diketiminato ligands. Dalton Trans 2011; 40:7718-29. [DOI: 10.1039/c1dt10202h] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Tomson NC, Arnold J, Bergman RG. Synthesis, Characterization, and Reactions of Isolable (β-Diketiminato)Nb(III) Imido Complexes. Organometallics 2010; 29:5010-5025. [PMID: 21116450 PMCID: PMC2992439 DOI: 10.1021/om1002528] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have investigated both the chemical reduction of (BDI)Nb(V) imido complexes (BDI = HC[C(Me)NAr](2); Ar = 2,6-(i)Pr(2)-C(6)H(3)) to the formal Nb(III) oxidation state and the ability of these Nb(III) complexes to behave as two-electron reductants. The reduction of the Nb(V) species was found to depend heavily on the nature of available supporting ligands, but the chemistry of the reduced compounds proceeded cleanly with a number of unsaturated organic reagents. Accordingly, the novel Nb(V) bis(imido) complexes supported by the monoazabutadiene (mad) ligand (mad)Nb(N(t)Bu)(NAr)(L') (L' = py, thf) were formed by either KC(8) reduction of (BDI)Nb(N(t)Bu)Cl(2)(py) in the absence of strong π-acids or by H(2) reduction of the Nb(V) dimethyl complex (BDI)Nb(N(t)Bu)Me(2) in THF. These products are likely formed though an intramolecular, 2 e(-) reductive C-N bond cleavage, as has been observed previously for related Group 4 systems, suggesting that transient Nb(III) intermediates were present in both cases. In the presence of 1,2-bis(dimethylphosphino)ethane (dmpe), KC(8) reduction of (BDI)Nb(N(t)Bu)Cl(2)(py) was arrested at the Nb(IV) oxidation state to give (BDI)Nb(N(t)Bu)Cl(dmpe), which was characterized by solution-state EPR spectroscopy as a Nb-centered paramagnet with strong coupling to the two equivalent phosphorus nuclei (A(iso){(93)Nb} = 120.5×10(-4) cm(-1), A(iso){(31)P} = 31.0×10(-4) cm(-1), g(iso) = 1.9815). When strong π-acids were used to intercept the thermally unstable Nb(III) complex (BDI)Nb(N(t)Bu)(py) prior to reductive cleavage of the ligand C-N bond, the thermally stable Nb(III) species (BDI)Nb(N(t)Bu)(CX)(2)(L″) (X = O, L″ = py; X = NXyl, L″ = CNXyl; Xyl = 2,6-Me(2)-C(6)H(3)) were obtained in good yields. The Nb(III) complexes (BDI)Nb(N(t)Bu)py, (BDI)Nb(N(t)Bu)(CO)(2)(py) and (BDI)Nb(N(t)Bu)(CO)(2) were subsequently investigated for their ability to serve as two-electron reducing reagents for both metal-ligand multiple bond formation and for the reduction of organic π-systems. The reduction of mesityl azide by (BDI)Nb(N(t)Bu)(py) and diphenylsulfoxide by (BDI)Nb(N(t)Bu)(CO)(2) led to the monomeric bis(imido) and dimeric oxo complexes (BDI)Nb(N(t)Bu)(NMes)(py) and [(BDI)Nb(N(t)Bu)](2)(μ2-O)(2), respectively. MeLi addition to (BDI)Nb(N(t)Bu)(CO)(2)(py) resulted in the formation of a Nb-acylate via methide addition to one of the carbonyl carbons. The acylate product was revealed to have a short Nb-C(acylate) bond distance (2.059(4) Å), consistent with multiple Nb-C bond character resulting from Nb(III) back-bonding into the acylate carbon. The interaction of (BDI)Nb(N(t)Bu)(CO)(2) with two equivalents of 4,4'-dichlorobenzophenone resulted in the clean, quantitative formation of the corresponding pinacol coupling product, but introduction of the ketone in 1: 1 molar ratios resulted in mixtures of the pinacol product and the starting material, suggesting that ketone coordination to the Nb(III) complex may be reversible. Relatedly, addition of 1-phenyl-1-propyne to (BDI)Nb(N(t)Bu)(CO)(2) formed a thermally unstable 1: 1 Nb/alkyne complex, as characterized by NMR and IR spectroscopies; reaction of this species with HCl/MeOH yielded a 2: 1 mixture of 1-phenyl-1-propene and the free alkyne, suggesting a high degree of covalency in the Nb-C bonds.
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Affiliation(s)
| | - John Arnold
- University of California, Berkeley, California 94720
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28
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Neshat A, Schmidt JAR. Derivatization of Niobium Complexes Bearing Imido and Acetophenone Imine Ligands. Organometallics 2010. [DOI: 10.1021/om100657r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Abdollah Neshat
- Department of Chemistry, The University of Toledo, 2801 W. Bancroft Street, MS 602, Toledo, Ohio 43606-3390, United States
| | - Joseph A. R. Schmidt
- Department of Chemistry, The University of Toledo, 2801 W. Bancroft Street, MS 602, Toledo, Ohio 43606-3390, United States
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29
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Tomson NC, Arnold J, Bergman RG. Halo, Alkyl, Aryl, and Bis(imido) Complexes of Niobium Supported by the beta-Diketiminato Ligand. Organometallics 2010; 29:2926-2942. [PMID: 20671985 DOI: 10.1021/om1001827] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Synthesis of the complex (BDI)Nb(N(t)Bu)Cl(2)py (BDI = HC[C(Me)N(2,6-iPr(2)-C(6)H(3))](2)) was achieved in high yield following the treatment of Nb(N(t)Bu)Cl(3)py(2) with Li(BDI)(OEt(2)). Substitution of the chlorides for fluorides was effected by introducing 2.0 equiv of Me(3)SnF in toluene, providing the pyridine-coordinated difluoride complex (BDI)Nb(N(t)Bu)F(2)py in modest yield. The pyridine ligands from both halide compounds were removed by treatment of the pyridine adducts with B(C(6)F(5))(3), affording the Lewis base-free complexes (BDI)Nb(NtBu)X(2) (X = Cl, F). Additionally, the Lewis base-free dichlorides of the (t)Bu-imido and Ar-imido (Ar = 2,6-(i)Pr(2)-C(6)H(3)) complexes were obtained following treatment of Nb(NR)Cl(3)(dme) (R = tBu, Ar) with Li(BDI)(OEt(2)). The pyridine-coordinated dichloride was alkylated and arylated to form the dimethyl complex (BDI)Nb(N(t)Bu)Me(2) (described previously, see text) and the mono(p-tolyl) complex (BDI)Nb(N(t)Bu)Cl(p-tol), the latter of which was methylated with MeMgBr to yield the mixed alkyl/aryl complex (BDI)Nb(N(t)Bu)Me(p-tol) in good yield. A rare example of a Group 5 bis((t)Bu-imido) species was synthesized in good yield via treatment of (BDI)Nb(N(t)Bu)Cl(2)py with 2.0 equiv of LiNHtBu to form (BDI)Nb(NtBu)(2)py. Exchange of the coordinated pyridine ligand for either pyridine-d(5) or dmap (p-(dimethylamino)pyridine) was shown to occur through a dissociative mechanism, allowing for removal of the coordinated Lewis base by treatment with B(C(6)F(5))(3). The resulting average C(2v)-symmetric tetracoordinate bis(imido) complex (BDI)Nb(N(t)Bu)(2) was characterized in solution by NMR spectroscopy and observed to undergo clean thermal decomposition to yield (BDI(#))Nb(N(t)Bu)(NH(t)Bu) (BDI(#) = H(2)C=C(NAr)CH=C(NAr)Me) over several hours at room temperature. Treatment of the four-coordinate bis(imido) with (t)BuNCO resulted in clean [2 + 2] cycloaddition to yield an oxaazametallacyclobutane complex, which was further observed to extrude (t)BuN=C=N(t)Bu over 12 h at room temperature. The molecular structures of (BDI)Nb(N(t)Bu)Cl(2)py, (BDI)Nb(NAr)Cl(2), (BDI)Nb(N(t)Bu)Me(2), (BDI)Nb(N(t)Bu)Cl(p-tol), (BDI)Nb(N(t)Bu)(2)py, and (BDI)Nb(NtBu)(2)(dmap) were determined crystallographically. Finally, DFT (BP86) geometry optimization calculations on a model complex of the thermally unstable four-coordinate bis(imido) species allowed for identification of the orbital interactions leading to activation of the imido groups through mixing with the BDI frontier orbitals.
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Affiliation(s)
- Neil C Tomson
- Department of Chemistry, University of California, Berkeley, California 94720
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30
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Adhikari D, Basuli F, Orlando JH, Gao X, Huffman JC, Pink M, Mindiola DJ. Zwitterionic and Cationic Titanium and Vanadium Complexes Having Terminal M−C Multiple Bonds. The Role of the β-Diketiminate Ligand in Formation of Charge-Separated Species. Organometallics 2009. [DOI: 10.1021/om900115v] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Debashis Adhikari
- Molecular Structure Center and the Department of Chemistry, Indiana University, Bloomington, Indiana 47405
| | | | - Justin H. Orlando
- Molecular Structure Center and the Department of Chemistry, Indiana University, Bloomington, Indiana 47405
| | - Xinfeng Gao
- Molecular Structure Center and the Department of Chemistry, Indiana University, Bloomington, Indiana 47405
| | - John C. Huffman
- Molecular Structure Center and the Department of Chemistry, Indiana University, Bloomington, Indiana 47405
| | - Maren Pink
- Molecular Structure Center and the Department of Chemistry, Indiana University, Bloomington, Indiana 47405
| | - Daniel J. Mindiola
- Molecular Structure Center and the Department of Chemistry, Indiana University, Bloomington, Indiana 47405
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