Cp* Noninnocence Leads to a Remarkably Weak C–H Bond via Metallocene Protonation

Chalkley, Matthew J.; Oyala, Paul H.; Peters, Jonas C.

doi:10.1021/jacs.9b00193

Title: Cp* Noninnocence Leads to a Remarkably Weak C–H Bond via Metallocene Protonation

Journal Article · Thu Feb 21 00:00:00 EST 2019 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/jacs.9b00193· OSTI ID:1698028

^[1];

^[1]

California Institute of Technology (CalTech), Pasadena, CA (United States)

Metallocenes, including their permethylated variants, are extremely important in organometallic chemistry. In particular, many are synthetically useful either as oxidants (e.g., Cp₂Fe⁺) or as reductants (e.g., Cp₂Co, Cp*₂Co, and Cp*₂Cr). The latter have proven to be useful reagents in the reductive protonation of small-molecule substrates, including N₂. As such, understanding the behavior of these metallocenes in the presence of acids is paramount. In the present study, we undertake the rigorous characterization of the protonation products of Cp*₂Co using pulse electron paramagnetic resonance (EPR) techniques at low temperature. We provide unequivocal evidence for the formation of the ring-protonated isomers Cp*(exo/endo-η⁴-C₅Me₅H)Co⁺. Variable temperature Q-band (34 GHz) pulse EPR spectroscopy, in conjunction with density functional theory (DFT) predictions, are key to reliably assigning the Cp*(exo/endo-η⁴-C₅Me₅H)Co⁺ species. We also demonstrate that exo-protonation selectivity can be favored by using a bulkier acid and suggest this species is thus likely a relevant intermediate during catalytic nitrogen fixation given the bulky anilinium acids employed. Of further interest, we provide physical data to experimentally assess the C–H bond dissociation free energy (BDFE_C–H) for Cp*(exo-η⁴-C₅Me₅H)Co⁺. These experimental data support our prior DFT predictions of an exceptionally weak C–H bond (<29 kcal mol^–1), making this system among the most reactive (with respect to C–H bond strength) to be thoroughly characterized. Furthermore, these data also point to the propensity of Cp*(exo-η⁴-C₅Me₅H)Co to mediate hydride (H^–) transfer. Our findings are not limited to the present protonated metallocene system. Accordingly, we outline an approach to rationalizing the reactivity of arene-protonated metal species, using decamethylnickelocene as an additional example.

View Accepted Manuscript (DOE)

Cite

Export

Save

Research Organization:: California Institute of Technology (CalTech), Pasadena, CA (United States)

Sponsoring Organization:: USDOE Office of Science (SC)

Grant/Contract Number:: SC0019136

OSTI ID:: 1698028

Journal Information:: Journal of the American Chemical Society, Vol. 141, Issue 11; ISSN 0002-7863

Publisher:: American Chemical Society (ACS)Copyright Statement

Country of Publication:: United States

Language:: English

References (47)

The Structure of iron Bis-Cyclopentadienyl Wilkinson, Geoffrey; Rosenblum, M.; Whiting, M. C. Journal of the American Chemical Society, Vol. 74, Issue 8 https://doi.org/10.1021/ja01128a527	journal	April 1952
Organometallic Electrochemistry: Origins, Development, and Future Geiger, William E. Organometallics, Vol. 26, Issue 24 https://doi.org/10.1021/om700558k	journal	October 2007
Catalytic Reduction of Dinitrogen to Ammonia at a Single Molybdenum Center Yandulov, D. V. Science, Vol. 301, Issue 5629 https://doi.org/10.1126/science.1085326	journal	July 2003
A molybdenum complex bearing PNP-type pincer ligands leads to the catalytic reduction of dinitrogen into ammonia Arashiba, Kazuya; Miyake, Yoshihiro; Nishibayashi, Yoshiaki Nature Chemistry, Vol. 3, Issue 2 https://doi.org/10.1038/nchem.906	journal	December 2010
Selective Catalytic Reduction of N ₂ to N ₂ H ₄ by a Simple Fe Complex Hill, Peter J.; Doyle, Laurence R.; Crawford, Andrew D. Journal of the American Chemical Society, Vol. 138, Issue 41 https://doi.org/10.1021/jacs.6b08802	journal	October 2016
Catalytic Nitrogen Fixation via Direct Cleavage of Nitrogen–Nitrogen Triple Bond of Molecular Dinitrogen under Ambient Reaction Conditions Arashiba, Kazuya; Eizawa, Aya; Tanaka, Hiromasa Bulletin of the Chemical Society of Japan, Vol. 90, Issue 10 https://doi.org/10.1246/bcsj.20170197	journal	October 2017
Catalytic N ₂ -to-NH ₃ Conversion by Fe at Lower Driving Force: A Proposed Role for Metallocene-Mediated PCET Chalkley, Matthew J.; Del Castillo, Trevor J.; Matson, Benjamin D. ACS Central Science, Vol. 3, Issue 3 https://doi.org/10.1021/acscentsci.7b00014	journal	February 2017
Fe-Mediated Nitrogen Fixation with a Metallocene Mediator: Exploring p K _a Effects and Demonstrating Electrocatalysis Chalkley, Matthew J.; Del Castillo, Trevor J.; Matson, Benjamin D. Journal of the American Chemical Society, Vol. 140, Issue 19 https://doi.org/10.1021/jacs.8b02335	journal	April 2018
Protonation of Metallocenes by Strong Acids. Structure of the Cation Curphey, T. J.; Santer, J. O.; Rosenblum, M. Journal of the American Chemical Society, Vol. 82, Issue 19 https://doi.org/10.1021/ja01504a062	journal	October 1960
New high yield syntheses of ruthenocene and osmocene and their decamethyl derivatives. The crystal structure of [Ru(η5-C5Me5)2] Liles, David C.; Shaver, Alan; Singleton, Eric Journal of Organometallic Chemistry, Vol. 288, Issue 2 https://doi.org/10.1016/0022-328X(85)87286-7	journal	June 1985
Studies on the reactivity of metal π-complexes Court, T. L.; Werner, H. Journal of Organometallic Chemistry, Vol. 65, Issue 2 https://doi.org/10.1016/S0022-328X(00)91276-2	journal	January 1974
Permethylated Electron-Excess Metallocenes Koelle, Ulrich; Khouzami, Fouad Angewandte Chemie International Edition in English, Vol. 19, Issue 8 https://doi.org/10.1002/anie.198006401	journal	August 1980
Kinetics and mechanism of the reduction of protons to hydrogen by cobaltocene Koelle, Ulrich; Infelta, Pierre P.; Graetzel, Michael Inorganic Chemistry, Vol. 27, Issue 5 https://doi.org/10.1021/ic00278a026	journal	March 1988
Catalytic Formation of Ammonia from Molecular Dinitrogen by Use of Dinitrogen-Bridged Dimolybdenum–Dinitrogen Complexes Bearing PNP-Pincer Ligands: Remarkable Effect of Substituent at PNP-Pincer Ligand Kuriyama, Shogo; Arashiba, Kazuya; Nakajima, Kazunari Journal of the American Chemical Society, Vol. 136, Issue 27 https://doi.org/10.1021/ja5044243	journal	June 2014
Catalytic conversion of nitrogen to ammonia by an iron model complex Anderson, John S.; Rittle, Jonathan; Peters, Jonas C. Nature, Vol. 501, Issue 7465 https://doi.org/10.1038/nature12435	journal	September 2013
A Synthetic Single-Site Fe Nitrogenase: High Turnover, Freeze-Quench ⁵⁷ Fe Mössbauer Data, and a Hydride Resting State Del Castillo, Trevor J.; Thompson, Niklas B.; Peters, Jonas C. Journal of the American Chemical Society, Vol. 138, Issue 16 https://doi.org/10.1021/jacs.6b01706	journal	January 2016
Characterization of an Fe≡N–NH ₂ Intermediate Relevant to Catalytic N ₂ Reduction to NH ₃ Anderson, John S.; Cutsail, George E.; Rittle, Jonathan Journal of the American Chemical Society, Vol. 137, Issue 24 https://doi.org/10.1021/jacs.5b03432	journal	June 2015
Nitrogen Fixation via a Terminal Fe(IV) Nitride Thompson, Niklas B.; Green, Michael T.; Peters, Jonas C. Journal of the American Chemical Society, Vol. 139, Issue 43 https://doi.org/10.1021/jacs.7b09364	journal	October 2017
Studies Relevant to Catalytic Reduction of Dinitrogen to Ammonia by Molybdenum Triamidoamine Complexes Yandulov, Dmitry V.; Schrock, Richard R. Inorganic Chemistry, Vol. 44, Issue 4 https://doi.org/10.1021/ic040095w	journal	February 2005
Molybdenum Complexes that Contain a Calix[6]azacryptand Ligand as Catalysts for Reduction of N ₂ to Ammonia Wickramasinghe, Lasantha A.; Schrock, Richard R.; Tsay, Charlene Inorganic Chemistry, Vol. 57, Issue 24 https://doi.org/10.1021/acs.inorgchem.8b02903	journal	December 2018
Protonation of Ferrocene: A Low-Temperature X-ray Diffraction Study of [Cp ₂ FeH](PF ₆ ) Reveals an Iron-Bound Hydrido Ligand Malischewski, Moritz; Seppelt, Konrad; Sutter, Jörg Angewandte Chemie International Edition, Vol. 56, Issue 43 https://doi.org/10.1002/anie.201704854	journal	September 2017
Pseudo field modulation in EPR spectroscopy Hyde, J. S.; Pasenkiewicz-Gierula, M.; Jesmanowicz, A. Applied Magnetic Resonance, Vol. 1, Issue 3 https://doi.org/10.1007/BF03166028	journal	December 1990
Redetermination of the Hyperfine Splitting in the Ground State of Atomic Hydrogen Wittke, J. P.; Dicke, R. H. Physical Review, Vol. 103, Issue 3 https://doi.org/10.1103/PhysRev.103.620	journal	August 1956
Transition-Metal Hydride Radical Cations Hu, Yue; Shaw, Anthony P.; Estes, Deven P. Chemical Reviews, Vol. 116, Issue 15 https://doi.org/10.1021/acs.chemrev.5b00532	journal	February 2016
Cobalt-59 nuclear quadrupole resonance spectroscopy Brown, Theodore L. Accounts of Chemical Research, Vol. 7, Issue 12 https://doi.org/10.1021/ar50084a003	journal	December 1974
A Nickel Hydride Complex in the Active Site of Methyl-Coenzyme M Reductase: Implications for the Catalytic Cycle Harmer, Jeffrey; Finazzo, Cinzia; Piskorski, Rafal Journal of the American Chemical Society, Vol. 130, Issue 33 https://doi.org/10.1021/ja710949e	journal	August 2008
Modeling the Signatures of Hydrides in Metalloenzymes: ENDOR Analysis of a Di-iron Fe(μ-NH)(μ-H)Fe Core Kinney, R. Adam; Saouma, Caroline T.; Peters, Jonas C. Journal of the American Chemical Society, Vol. 134, Issue 30 https://doi.org/10.1021/ja303739g	journal	July 2012
760. A new type of transition metal–cyclopentadiene compound Green, M. L. H.; Pratt, L.; Wilkinson, G. J. Chem. Soc., Vol. 0, Issue 0 https://doi.org/10.1039/JR9590003753	journal	January 1959
Electrochemistry of transition metal π-complexes. IV. Oxidation of cyclopentadienyl diolefine and cyclobutadiene cobalt complexes Koelle, Ulrich Inorganica Chimica Acta, Vol. 47 https://doi.org/10.1016/S0020-1693(00)89300-7	journal	January 1981
Thermodynamic Hydricity of Transition Metal Hydrides Wiedner, Eric S.; Chambers, Matthew B.; Pitman, Catherine L. Chemical Reviews, Vol. 116, Issue 15 https://doi.org/10.1021/acs.chemrev.6b00168	journal	June 2016
Thermodynamic and kinetic hydricities of metal-free hydrides Ilic, Stefan; Alherz, Abdulaziz; Musgrave, Charles B. Chemical Society Reviews, Vol. 47, Issue 8 https://doi.org/10.1039/C7CS00171A	journal	January 2018
C−H Bond Activation of Decamethylcobaltocene Mediated by a Nitrogenase Fe ₈ S ₇ P-Cluster Model Ohki, Yasuhiro; Murata, Ayuro; Imada, Motosuke Inorganic Chemistry, Vol. 48, Issue 10 https://doi.org/10.1021/ic900284f	journal	May 2009
Molecular Dynamics of Neutral and Protonated Ferrocene Bühl, Michael; Grigoleit, Sonja Organometallics, Vol. 24, Issue 7 https://doi.org/10.1021/om049243g	journal	February 2005
Mechanisms and dynamics of protonation and lithiation of ferrocene Sharma, Nishant; Ajay, Jayanth K.; Venkatasubbaiah, Krishnan Physical Chemistry Chemical Physics, Vol. 17, Issue 34 https://doi.org/10.1039/C5CP03735B	journal	January 2015
An electrochemical study of the protonation site of the cobaltocene anion and of cyclopentadienylcobalt(I) dicarbollides Geiger, William E.; Bowden, William L.; El Murr, Nabil Inorganic Chemistry, Vol. 18, Issue 9 https://doi.org/10.1021/ic50199a006	journal	September 1979
Untersuchungen zur reaktivität von metall-π-komplexen Werner, H.; Dernberger, Th. Journal of Organometallic Chemistry, Vol. 198, Issue 1 https://doi.org/10.1016/S0022-328X(00)84668-9	journal	September 1980
Cyclopentadiene-mediated hydride transfer from rhodium complexes Pitman, C. L.; Finster, O. N. L.; Miller, A. J. M. Chemical Communications, Vol. 52, Issue 58 https://doi.org/10.1039/C6CC00575F	journal	January 2016
Proton–hydride tautomerism in hydrogen evolution catalysis Quintana, Luis M. Aguirre; Johnson, Samantha I.; Corona, Sydney L. Proceedings of the National Academy of Sciences, Vol. 113, Issue 23 https://doi.org/10.1073/pnas.1606018113	journal	May 2016
Role of Ligand Protonation in Dihydrogen Evolution from a Pentamethylcyclopentadienyl Rhodium Catalyst Johnson, Samantha I.; Gray, Harry B.; Blakemore, James D. Inorganic Chemistry, Vol. 56, Issue 18 https://doi.org/10.1021/acs.inorgchem.7b01698	journal	September 2017
Mn-, Fe-, and Co-Catalyzed Radical Hydrofunctionalizations of Olefins Crossley, Steven W. M.; Obradors, Carla; Martinez, Ruben M. Chemical Reviews, Vol. 116, Issue 15 https://doi.org/10.1021/acs.chemrev.6b00334	journal	June 2016
Synthetic Applications of Proton-Coupled Electron Transfer Gentry, Emily C.; Knowles, Robert R. Accounts of Chemical Research, Vol. 49, Issue 8 https://doi.org/10.1021/acs.accounts.6b00272	journal	July 2016
Water: The Ideal Hydrogen-Atom Source in Free-Radical Chemistry Mediated by TiIII and Other Single-Electron-Transfer Metals? Cuerva, Juan M.; Campaña, Araceli G.; Justicia, José Angewandte Chemie International Edition, Vol. 45, Issue 33 https://doi.org/10.1002/anie.200600831	journal	August 2006
Proton-Coupled Electron Transfer in the Reduction of Arenes by SmI ₂ –Water Complexes Chciuk, Tesia V.; Flowers, Robert A. Journal of the American Chemical Society, Vol. 137, Issue 35 https://doi.org/10.1021/jacs.5b07518	journal	August 2015
Proton-Coupled Electron Transfer in the Reduction of Carbonyls by Samarium Diiodide–Water Complexes Chciuk, Tesia V.; Anderson, William R.; Flowers, Robert A. Journal of the American Chemical Society, Vol. 138, Issue 28 https://doi.org/10.1021/jacs.6b05879	journal	July 2016
Interplay between Substrate and Proton Donor Coordination in Reductions of Carbonyls by SmI ₂ –Water Through Proton-Coupled Electron-Transfer Chciuk, Tesia V.; Anderson, William R.; Flowers, Robert A. Journal of the American Chemical Society, Vol. 140, Issue 45 https://doi.org/10.1021/jacs.8b08890	journal	October 2018
SmI ₂ (H ₂ O) _n Reduction of Electron Rich Enamines by Proton-Coupled Electron Transfer Kolmar, Scott S.; Mayer, James M. Journal of the American Chemical Society, Vol. 139, Issue 31 https://doi.org/10.1021/jacs.7b03667	journal	July 2017
Permethylmetallocene, III. Decamethylnickelocen: der Neutralkomplex, das Monokation, das Dikation und ihre Additionsreaktionen Kölle, Ulrich; Khouzami, Fouad; Lueken, Heiko Chemische Berichte, Vol. 115, Issue 3 https://doi.org/10.1002/cber.19821150334	journal	March 1982

Cited By (7)

Isolation of a Perfectly Linear Uranium(II) Metallocene Guo, Fu‐Sheng; Tsoureas, Nikolaos; Huang, Guo‐Zhang Angewandte Chemie, Vol. 132, Issue 6 https://doi.org/10.1002/ange.201912663	journal	December 2019
Coordination-induced O–H bond weakening in Sm( ii )-water complexes Bartulovich, C. O.; Flowers, R. A. Dalton Transactions, Vol. 48, Issue 43 https://doi.org/10.1039/c9dt03352a	journal	January 2019
Electron acceptors promote proton–hydride tautomerism in low valent rhenium β-diketiminates Lohrey, Trevor D.; Fostvedt, Jade I.; Bergman, Robert G. Chemical Communications, Vol. 56, Issue 26 https://doi.org/10.1039/c9cc09475j	journal	January 2020
Snapshots of a Migrating H-Atom: Characterization of a Reactive Iron(III) Indenide Hydride and its Nearly Isoenergetic Ring-Protonated Iron(I) Isomer Drover, Marcus W.; Schild, Dirk J.; Oyala, Paul H. Angewandte Chemie International Edition, Vol. 58, Issue 43 https://doi.org/10.1002/anie.201909050	journal	September 2019
A hemilabile manganese( i )–phenol complex and its coordination induced O–H bond weakening Kadassery, Karthika J.; Crawley, Matthew R.; MacMillan, Samantha N. Dalton Transactions https://doi.org/10.1039/d0dt00973c	journal	January 2020
Snapshots of a Migrating H‐Atom: Characterization of a Reactive Iron(III) Indenide Hydride and its Nearly Isoenergetic Ring‐Protonated Iron(I) Isomer Drover, Marcus W.; Schild, Dirk J.; Oyala, Paul H. Angewandte Chemie, Vol. 131, Issue 43 https://doi.org/10.1002/ange.201909050	journal	September 2019
Isolation of a Perfectly Linear Uranium(II) Metallocene Guo, Fu‐Sheng; Tsoureas, Nikolaos; Huang, Guo‐Zhang Angewandte Chemie International Edition, Vol. 59, Issue 6 https://doi.org/10.1002/anie.201912663	journal	February 2020

Similar Records

Generating Potent C–H PCET Donors: Ligand-Induced Fe-to-Ring Proton Migration from a Cp*Fe^III–H Complex Demonstrates a Promising Strategy

Journal Article · Mon Oct 26 00:00:00 EDT 2020 · Journal of the American Chemical Society · OSTI ID:1698028

Schild, Dirk J.; Drover, Marcus W.; Oyala, Paul H.; +1 more

Hydrido methylidene, hydrido vinylidene, hydrido oxo, and hydrido formaldehyde derivatives of bis(pentamethylcyclopentadienyl)tantalum

Journal Article · Wed Aug 20 00:00:00 EDT 1986 · J. Am. Chem. Soc.; (United States) · OSTI ID:1698028

van Asselt, A; Burger, B J; Gibson, V C; +1 more

Cooperative Activation of CO₂ and Epoxide by a Heterobinuclear Al–Fe Complex via Radical Pair Mechanisms

Journal Article · Mon Feb 14 00:00:00 EST 2022 · Journal of the American Chemical Society · OSTI ID:1698028

Sinhababu, Soumen; Radzhabov, Maxim R.; Telser, Joshua; +1 more

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Bond dissociation free energy
Reaction mechanisms
Proton coupled electron transfer
Sandwich compounds
Electron paramagnetic resonance spectroscopy

CCDC 1902775: Experimental Crystal Structure Determination Chalkley, Matthew J.; Oyala, Paul H.; Peters, Jonas C. https://doi.org/10.5517/ccdc.csd.cc21vzvr The current record is supplemented by this dataset	dataset	January 2019
CCDC 1902776: Experimental Crystal Structure Determination Chalkley, Matthew J.; Oyala, Paul H.; Peters, Jonas C. https://doi.org/10.5517/ccdc.csd.cc21vzws The current record is supplemented by this dataset	dataset	January 2019

Title: Cp* Noninnocence Leads to a Remarkably Weak C–H Bond via Metallocene Protonation

Citation Formats

References (47)

Cited By (7)

Linked Research (2)

Similar Records

Related Subjects