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Baek SY, Kurogi T, Kang D, Kamitani M, Kwon S, Solowey DP, Chen CH, Pink M, Carroll PJ, Mindiola DJ, Baik MH. Room-Temperature Ring-Opening of Quinoline, Isoquinoline, and Pyridine with Low-Valent Titanium. J Am Chem Soc 2017; 139:12804-12814. [PMID: 28812886 DOI: 10.1021/jacs.7b07433] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The complex (PNP)Ti═CHtBu(CH2tBu) (PNP = N[2-PiPr2-4-methylphenyl]2-) dehydrogenates cyclohexane to cyclohexene by forming a transient low-valent titanium-alkyl species, [(PNP)Ti(CH2tBu)], which reacts with 2 equiv of quinoline (Q) at room temperature to form H3CtBu and a Ti(IV) species where the less hindered C2═N1 bond of Q is ruptured and coupled to another equivalent of Q. The product isolated from this reaction is an imide with a tethered cycloamide group, (PNP)Ti═N[C18H13N] (1). Under photolytic conditions, intramolecular C-H bond activation across the imide moiety in 1 occurs to form 2, and thermolysis reverses this process. The reaction of 2 equiv of isoquinoline (Iq) with intermediate [(PNP)Ti(CH2tBu)] results in regioselective cleavage of the C1═N2 and C1-H bonds, which eventually couple to form complex 3, a constitutional isomer of 1. Akin to 1, the transient [(PNP)Ti(CH2tBu)] complex can ring-open and couple two pyridine molecules, to produce a close analogue of 1, complex (PNP)Ti═N[C10H9N] (4). Multinuclear and multidimensional NMR spectra confirm structures for complexes 1-4, whereas solid-state structural analysis reveals the structures of 2, 3, and 4. DFT calculations suggest an unprecedented mechanism for ring-opening of Q where the reactive intermediate in the low-spin manifold crosses over to the high-spin surface to access a low-energy transition state but returns to the low-spin surface immediately. This double spin-crossover constitutes a rare example of a two-state reactivity, which is key for enabling the reaction at room temperature. The regioselective behavior of Iq ring-opening is found to be due to electronic effects, where the aromatic resonance of the bicycle is maintained during the key C-C coupling event.
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Affiliation(s)
- Seung-Yeol Baek
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Republic of Korea.,Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS) , Daejeon 34141, Republic of Korea
| | - Takashi Kurogi
- Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Dahye Kang
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Republic of Korea.,Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS) , Daejeon 34141, Republic of Korea
| | - Masahiro Kamitani
- Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Seongyeon Kwon
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Republic of Korea.,Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS) , Daejeon 34141, Republic of Korea
| | - Douglas P Solowey
- Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Chun-Hsing Chen
- Department of Chemistry and Molecular Structure Center, Indiana University , Bloomington, Indiana 47405, United States
| | - Maren Pink
- Department of Chemistry and Molecular Structure Center, Indiana University , Bloomington, Indiana 47405, United States
| | - Patrick J Carroll
- Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Daniel J Mindiola
- Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Mu-Hyun Baik
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Republic of Korea.,Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS) , Daejeon 34141, Republic of Korea
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Clough BA, Mellino S, Protchenko AV, Slusarczyk M, Stevenson LC, Blake MP, Xie B, Clot E, Mountford P. New Titanium Borylimido Compounds: Synthesis, Structure, and Bonding. Inorg Chem 2017; 56:10794-10814. [PMID: 28836774 DOI: 10.1021/acs.inorgchem.7b01831] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a combined experimental and computational study of the synthesis and electronic structure of titanium borylimido compounds. Three new synthetic routes to this hitherto almost unknown class of Group 4 imide are presented. The double-deprotonation reaction of the borylamine H2NB(NAr'CH)2 (Ar' = 2,6-C6H3iPr2) with Ti(NMe2)2Cl2 gave Ti{NB(NAr'CH)2}Cl2(NHMe2)2, which was easily converted to Ti{NB(NAr'CH)2}Cl2(py)3. This compound is an entry point to other borylimides, for example, reacting with Li2N2pyrNMe to form Ti(N2pyrNMe){NB(NAr'CH)2}(py)2 and with 2 equiv of NaCp to give Cp2Ti{NB(NAr'CH)2}(py) (23). Borylamine-tert-butylimide exchange between H2NB(NAr'CH)2 and Cp*Ti(NtBu)Cl(py) under forcing conditions afforded Cp*Ti{NB(NAr'CH)2}Cl(py), which could be further substituted with guanidinate or pyrrolide-amine ligands to give Cp*Ti(hpp){NB(NAr'CH)2} (16) and Cp*Ti(NpyrNMe2){NB(NAr'CH)2} (17). The Ti-Nim distances in compounds with the NB(NAr'CH)2 ligand were comparable to those of the corresponding arylimides. Dialkyl- or diaryl-substituted borylamines do not undergo the analogous double-deprotonation or imide-amine exchange reactions. Reaction of (Cp″2Ti)2(μ2:η1,η1-N2) with N3BMes2 gave the base-free, diarylborylimide Cp″2Ti(NBMes2) (26) by an oxidative route; this compound has a relatively long Ti-Nim bond and large Cp″-Ti-Cp″ angle. Reaction of 16 with H2NtBu formed equilibrium mixtures with H2NB(NAr'CH)2 and Cp*Ti(hpp)(NtBu) (ΔrG = -1.0 kcal mol-1). In contrast, the dialkylborylimide Cp*Ti{MeC(NiPr)2}(NBC8H14) (2) reacted quantitatively with H2NtBu to give the corresponding tert-butylimide and borylamine. The electronic structures and imide-amine exchange reactions of half-sandwich and sandwich titanium borylimides have been evaluated using density functional theory (DFT), supported by quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analysis, and placed more generally in context with the well-established alkyl- and arylimides and hydrazides. The calculations find that Ti-Nim bonds for borylimides are stronger and more covalent than in their organoimido or hydrazido analogues, and are strongest for alkyl- and arylborylimides. Borylamine-tert-butylimide exchange reactions fail for H2NBR2 (R = hydrocarbyl) but not for H2NB(NAr'CH)2 because the increased strength of the new Ti-Nim bond for the former is outweighed by the increased net H-N bond strengths in the borylamine. Variation of the Ti-Nim bond length over short distances is dominated by π-interactions with any appropriate orbital on the Nim atom organic substituent. However, over the full range of imides and hydrazides studied, overall bond energies do not correlate with bond length but with the Ti-Nim σ-bond character and the orthogonal π-interaction.
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Affiliation(s)
- Benjamin A Clough
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K
| | - Simona Mellino
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K
| | - Andrey V Protchenko
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K
| | - Martin Slusarczyk
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K
| | - Laura C Stevenson
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K
| | - Matthew P Blake
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K
| | - Bowen Xie
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K
| | - Eric Clot
- Institut Charles Gerhardt Montpellier, UMR 5253, CNRS-UM-ENSCM, Université de Montpellier , cc 1501, Place Eugéne Bataillon, F-34095 Montpellier Cedex 5, France
| | - Philip Mountford
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K
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Mellino S, Stevenson LC, Clot E, Mountford P. Reactions of Titanium Imides and Hydrazides with Boranes. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00477] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Simona Mellino
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Laura C. Stevenson
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Eric Clot
- Institut
Charles Gerhardt Montpellier, UMR 5253 CNRS-UM-ENSCM, Université de Montpellier, cc 1501, Place Eugéne Bataillon, F-34095 Montpellier Cedex 5, France
| | - Philip Mountford
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
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Groom LR, Russell AF, Schwarz AD, Mountford P. Reactions of a Cyclopentadienyl–Amidinate Titanium Benzimidamido Complex. Organometallics 2014. [DOI: 10.1021/om4011752] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Laura R. Groom
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Adam F. Russell
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Andrew D. Schwarz
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Philip Mountford
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
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Groom LR, Schwarz AD, Nova A, Clot E, Mountford P. Synthesis and Reactions of a Cyclopentadienyl-Amidinate Titanium tert-Butoxyimido Compound. Organometallics 2013. [DOI: 10.1021/om401008a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Laura R. Groom
- Chemistry Research
Laboratory, Department of
Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Andrew D. Schwarz
- Chemistry Research
Laboratory, Department of
Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Ainara Nova
- Institut
Charles Gerhardt, Université Montpellier 2, CNRS 5253, cc 1501, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - Eric Clot
- Institut
Charles Gerhardt, Université Montpellier 2, CNRS 5253, cc 1501, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - Philip Mountford
- Chemistry Research
Laboratory, Department of
Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
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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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Unruangsri J, Morgan H, Schwarz AD, Schofield AD, Mountford P. Synthesis and Reactivity of Titanium Hydrazido Complexes Supported by Diamido-Ether Ligands. Organometallics 2013. [DOI: 10.1021/om400311w] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Junjuda Unruangsri
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, Mansfield
Road, Oxford OX1 3TA, U.K
| | - Hannah Morgan
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, Mansfield
Road, Oxford OX1 3TA, U.K
| | - Andrew D. Schwarz
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, Mansfield
Road, Oxford OX1 3TA, U.K
| | - A. Daniel Schofield
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, Mansfield
Road, Oxford OX1 3TA, U.K
| | - Philip Mountford
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, Mansfield
Road, Oxford OX1 3TA, U.K
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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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Tiong PJ, Groom LR, Clot E, Mountford P. Synthesis, Bonding and Reactivity of a Terminal Titanium Alkylidene Hydrazido Compound. Chemistry 2013; 19:4198-216. [DOI: 10.1002/chem.201203905] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Indexed: 11/10/2022]
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Schwarz AD, Onn CS, Mountford P. A Remarkable Switch from a Diamination to a Hydrohydrazination Catalyst and Observation of an Unprecedented Catalyst Resting State. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201206249] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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11
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Schwarz AD, Onn CS, Mountford P. A Remarkable Switch from a Diamination to a Hydrohydrazination Catalyst and Observation of an Unprecedented Catalyst Resting State. Angew Chem Int Ed Engl 2012; 51:12298-302. [DOI: 10.1002/anie.201206249] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/02/2012] [Indexed: 11/07/2022]
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12
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Fuller AM, Hughes DL, Jones GA, Lancaster SJ. The structure and chemistry of tris(pentafluorophenyl)borane protected mononuclear nitridotitanium complexes. Dalton Trans 2012; 41:5599-609. [DOI: 10.1039/c2dt00056c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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