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Zurakowski JA, Durfy CS, Stocek NB, Fanchini G, Drover MW. Oxidatively-induced C(sp 3)-C(sp 3) bond formation at a tucked-in iron(iii) complex. Chem Sci 2024; 15:10359-10365. [PMID: 38994411 PMCID: PMC11234878 DOI: 10.1039/d4sc03292f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Accepted: 06/06/2024] [Indexed: 07/13/2024] Open
Abstract
Carbon-carbon (C-C) bond formation is a cornerstone of synthetic chemistry, relying on routes such as transition-metal mediated cross-coupling for the introduction of new carbon-based functionality. For {[M] n+-C} (M = metal) structural units, studies that offer well-defined relationships between metal oxidation state, hydrocarbon strain, and {[M] n+-C} bond thermochemistry are thus informative, providing a means to reliably access new product classes. Here, we show that one-electron oxidation of the iron tucked-in complex [(η6-C5Me4[double bond, length as m-dash]CH2)Fe(dnppe)] (dnppe = 1,2-bis(di-n-propylphosphino)ethane) results in C(sp3)-C(sp3) bond formation giving unique {Fe2} dimers. Freeze-quenched CW X-band EPR spectroscopy allowed for spectroscopic identification of the reactive [(η6-C5Me4[double bond, length as m-dash]CH2)Fe(dnppe)]+ intermediate. Density functional theory (DFT) calculations reveal a primarily Fe-centered radical and a weak {[Fe]-C} bond (BDE[Fe]-C = 24.5 kcal mol-1, c.f. BDEC-C(ethane) = 90 kcal mol-1). For comparison, a structurally analogous Fe(iii) methyl complex was prepared, [Cp*Fe(dnppe)(CH3)]+ (Cp* = C5Me5 -), where C(sp3)-C(sp3) coupling was not observed, consistent with a larger calculated BDE[Fe]-C value of 47.8 kcal mol-1. These data are analogized to the simple hydrocarbons ethane and cyclopropane, where a strain-induced BDEC-C decrease of 33 kcal mol-1 is witnessed on cyclization.
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Affiliation(s)
- Joseph A Zurakowski
- Department of Chemistry, Western University 1151 Richmond Street London ON N8K 3G6 Canada
- Department of Chemistry and Biochemistry, University of Windsor 401 Sunset Avenue Windsor ON N9B 3P4 Canada
| | - Connor S Durfy
- Department of Chemistry, Western University 1151 Richmond Street London ON N8K 3G6 Canada
| | - Noah B Stocek
- Department of Physics and Astronomy, Western University 1151 Richmond Street London ON N6A 3K7 Canada
| | - Giovanni Fanchini
- Department of Chemistry, Western University 1151 Richmond Street London ON N8K 3G6 Canada
- Department of Physics and Astronomy, Western University 1151 Richmond Street London ON N6A 3K7 Canada
| | - Marcus W Drover
- Department of Chemistry, Western University 1151 Richmond Street London ON N8K 3G6 Canada
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Cruz TFC, Loupy V, Veiros LF. Zinc-Catalyzed Hydroboration of Carbon Dioxide Amplified by Borane-Tethered Heteroscorpionate Bis(Pyrazolyl)methane Ligands. Inorg Chem 2024; 63:8244-8256. [PMID: 38656156 PMCID: PMC11080050 DOI: 10.1021/acs.inorgchem.4c00500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 04/09/2024] [Accepted: 04/11/2024] [Indexed: 04/26/2024]
Abstract
The borane-functionalized (BR2) bis(3,5-dimethylpyrazolyl)methane (LH) ligands 1a (BR2: 9-borabicyclo[3.3.1]nonane or 9-BBN), 1b (BR2: BCy2), and 1c (BR2: B(C6F5)2) were synthesized by the allylation-hydroboration of LH. Metalation of 1a,b with ZnCl2 yielded the heteroscorpionate dichloride complexes [(1a,b)ZnCl2] 3a,b. The reaction of 1a with ZnEt2 led to the formation of the zwitterionic complex [Et(1a)ZnEt(THF)] 5. The reaction of complex 3a with two equivalents of KHBEt3 under a carbon dioxide (CO2) atmosphere gave rise to the formation of the dimeric bis(formate) complex [(1a)Zn(OCHO)2]2 8, in which its borane moieties intermolecularly stabilize the formate ligands of opposite metal centers. The allylated precursor Lallyl and its zinc dichloride, diethyl and bis(formate) complexes [(Lallyl)ZnCl2] 2, [(Lallyl)ZnEt2] 4, and [(Lallyl)Zn(OCHO)2] 7 were also isolated. The catalyst systems composed of 1 mol % of 3a or 3b and two equivalents of KHBEt3 hydroborated CO2 at 1 bar with pinacolborane (HBPin) to the methanol-level product H3COBPin (and PinBOBPin) in yields of 42 or 86%, respectively. The catalyst systems using the unfunctionalized complex [(LH)ZnCl2] 6 and KHBEt3 or KHBEt3/nOctBR2 (BR2: 9-BBN or BCy2) hydroborated CO2 to H3COBPin but in 2.5- to 6-fold lower activities than those exhibited by 3a,b/KHBEt3. The hydroboration of CO2 using 8 as a catalyst led to yields of 39-43%, comparable to those obtained with 3a/KHBEt3. The results confirmed that the catalytic intermediates benefit from the incorporated boranes' intra- or intermolecular stabilizations.
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Affiliation(s)
- Tiago F. C. Cruz
- Centro de Química
Estrutural, Institute of Molecular Sciences, Departamento de Engenharia
Química, Instituto Superior Técnico,
Universidade de Lisboa, Av. Rovisco Pais, 1049 001 Lisboa, Portugal
| | - Valentin Loupy
- Centro de Química
Estrutural, Institute of Molecular Sciences, Departamento de Engenharia
Química, Instituto Superior Técnico,
Universidade de Lisboa, Av. Rovisco Pais, 1049 001 Lisboa, Portugal
| | - Luís F. Veiros
- Centro de Química
Estrutural, Institute of Molecular Sciences, Departamento de Engenharia
Química, Instituto Superior Técnico,
Universidade de Lisboa, Av. Rovisco Pais, 1049 001 Lisboa, Portugal
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Clapson ML, Dilinaer AD, Lanaque TCQ, Zurakowski JA, Austen BJH, Drover MW. Ynone Co-Coordination at a Nickel Borane Complex: An Assessment of Secondary Coordination Sphere Effects. Inorg Chem 2024; 63:6184-6191. [PMID: 38546051 DOI: 10.1021/acs.inorgchem.3c04264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Secondary coordination sphere ligand effects can be used to direct or organize small molecule substrates at a metal center. Herein, we assess the bifunctional ambiphilic diphosphine, tri-tert-butylboranyldiphosphinoethane (ttbbpe) and its ability to influence stereoselective substrate coordination, while appended to nickel. This report takes a synthetic/computational approach to test the impacts and limitations associated with ligand-directed substrate coordination using [Ni(ttbbpe)(η2:η2-COD)] (COD = 1,5-cyclooctadiene) and ynones (alkynes having an α-carbonyl group at the propargylic position) as model substrates.
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Affiliation(s)
- Marissa L Clapson
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
| | - A Dina Dilinaer
- Department of Chemistry, Western University, 1151 Richmond Street, London, Ontario N8K 3G6, Canada
| | - Trisha C Q Lanaque
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
| | - Joseph A Zurakowski
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
- Department of Chemistry, Western University, 1151 Richmond Street, London, Ontario N8K 3G6, Canada
| | - Brady J H Austen
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
- Department of Chemistry, Western University, 1151 Richmond Street, London, Ontario N8K 3G6, Canada
| | - Marcus W Drover
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
- Department of Chemistry, Western University, 1151 Richmond Street, London, Ontario N8K 3G6, Canada
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Durfy CS, Zurakowski JA, Jobin G, Drover MW. An Investigation of Allyl-Substituted Bis(Diphosphine) Iron Complexes: Towards Precursors for Cooperative CO 2 Activation. Chemistry 2024; 30:e202302721. [PMID: 37724786 DOI: 10.1002/chem.202302721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 09/18/2023] [Accepted: 09/19/2023] [Indexed: 09/21/2023]
Abstract
In developing homogenous catalysts capable of CO2 activation, interaction with a metal center is often imperative. This work provides primary efforts towards the cooperative activation of CO2 using a Lewis acidic secondary coordination sphere (SCS) and iron via a paired theoretical/experimental approach. Specifically, this study reports efforts towards [Fe(diphosphine)2 (N2 )] as a CO2 -coordinated synthon where diphosphine=1,2-bis(di(3-cyclohexylboranyl)propylphosphino)ethane) (P2 BCy 4 ) or its precursor, 1,2-bis(diallylphosphino)ethane (tape). Initial efforts toward the {Fe(0)-N2 } complex were focused on deprotonation reactions of [Fe(diphosphine)2 (H)(NCCH3 )]+ and reduction of [Fe(tape)2 Cl2 ]. In the latter case, a mixture of intramolecularly π-bonded alkene and associated metallacyclic Fe(II)-H species were produced - heating this mixture provided the hydride as the major product. Notably, the interconversion of this pair counters that of related intermolecular reactions between [Fe(depe)2 ] (depe=1,2-bis(diethylphosphino)ethane) and ethylene, where hydride formation occurs subsequent to π-coordination; this has been probed by theoretical calculations. Finally, reactivity of the metallacyclic {Fe(II)-H} complex with CO2 was probed, resulting in a pair of isomeric ferra(II)lactones.
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Affiliation(s)
- Connor S Durfy
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
- Department of Chemistry, Western University, 1151 Richmond Street, London, ON, N6A 3K7, Canada
| | - Joseph A Zurakowski
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
- Department of Chemistry, Western University, 1151 Richmond Street, London, ON, N6A 3K7, Canada
| | - Gabriel Jobin
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
- Department of Chemistry, Western University, 1151 Richmond Street, London, ON, N6A 3K7, Canada
| | - Marcus W Drover
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
- Department of Chemistry, Western University, 1151 Richmond Street, London, ON, N6A 3K7, Canada
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Zurakowski JA, Drover MW. Cooperative bond activations by a tucked-in iron complex. Chem Commun (Camb) 2023; 59:11349-11352. [PMID: 37656426 DOI: 10.1039/d3cc03325b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Herein, we report the first example of a 'tucked-in' iron diphosphine complex, formed through deprotonation of a Cp*-(CH̲3) (Cp* = C5Me5-) group by n-butyllithium. The reactivity of this complex was demonstrated by activation of organic and metal-containing substates, including CO2, benzaldehyde, Br-AuI-PPh3, B(C6F5)3, and HBCy2 (Cy = cyclohexyl).
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Affiliation(s)
- Joseph A Zurakowski
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, ON, N9B 3P4, Canada.
| | - Marcus W Drover
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, ON, N9B 3P4, Canada.
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