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Song H, Szymczak NK. Lewis Acid-Tethered (cAAC)-Copper Complexes: Reactivity for Hydride Transfer and Catalytic CO 2 Hydrogenation. Angew Chem Int Ed Engl 2024; 63:e202411099. [PMID: 38967599 DOI: 10.1002/anie.202411099] [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: 06/12/2024] [Revised: 07/04/2024] [Accepted: 07/05/2024] [Indexed: 07/06/2024]
Abstract
We present a series of borane-tethered cyclic (alkyl)(amino)carbene (cAAC)-copper complexes, including a borane-capped Cu(I) hydride. This hydride is unusually hydridic and reacts rapidly with both CO2 and 2,6-dimethylphenol at room temperature. Its reactivity is distinct from variants without a tethered borane, and the underlying principles governing the enhanced hydricity were evaluated experimentally and theoretically. These stoichiometric results were extended to catalytic CO2 hydrogenation, and the borane-tethered (intramolecular) system exhibits ~3-fold enhancement relative to an intermolecular system.
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Affiliation(s)
- Hayoung Song
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109, United States
| | - Nathaniel K Szymczak
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109, United States
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Bharti J, Chen L, Guo Z, Cheng L, Wellauer J, Wenger OS, von Wolff N, Lau KC, Lau TC, Chen G, Robert M. Visible-Light-Driven CO 2 Reduction with Homobimetallic Complexes. Cooperativity between Metals and Activation of Different Pathways. J Am Chem Soc 2023; 145:25195-25202. [PMID: 37947126 DOI: 10.1021/jacs.3c07799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Visible-light-driven reduction of CO2 to both CO and formate (HCOO-) was achieved in acetonitrile solutions using a homobimetallic Cu bisquaterpyridine complex. In the presence of a weak acid (water) as coreactant, the reaction rate was enhanced, and a total of ca. 766 TON (turnover number) was reached for the CO2 reduction, with 60% selectivity for formate and 28% selectivity for CO, using Ru(phen)32+ as a sensitizer and amines as sacrificial electron donors. Mechanistic studies revealed that with the help of cooperativity between two Cu centers, a bridging hydride is generated in the presence of a proton source (water) and further reacts with CO2 to give HCOO-. A second product, CO, was also produced in a parallel competitive pathway upon direct coordination of CO2 to the reduced complex. Mechanistic studies further allowed comparison of the observed reactivity to the monometallic Cu quaterpyridine complex, which only produced CO, and to the related homobimetallic Co bisquaterpyridine complex, that has been previously shown to generate formate following a mechanism not involving the formation of an intermediate hydride species.
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Affiliation(s)
- Jaya Bharti
- Université Paris Cité, Laboratoire d'Electrochimie Moléculaire, CNRS, F-75013, Paris, France
| | - Lingjing Chen
- School of Environment and Civil Engineering, Research Center for Eco-environmental Engineering, Dongguan University of Technology, Dongguan, Guangdong 523808, P. R. China
| | - Zhenguo Guo
- Department of Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong 999077, P. R. China
| | - Lin Cheng
- Department of Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong 999077, P. R. China
| | - Joël Wellauer
- Department of Chemistry, Universität Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, Universität Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Niklas von Wolff
- Université Paris Cité, Laboratoire d'Electrochimie Moléculaire, CNRS, F-75013, Paris, France
| | - Kai-Chung Lau
- Department of Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong 999077, P. R. China
| | - Tai-Chu Lau
- School of Environment and Civil Engineering, Research Center for Eco-environmental Engineering, Dongguan University of Technology, Dongguan, Guangdong 523808, P. R. China
- Department of Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong 999077, P. R. China
| | - Gui Chen
- School of Environment and Civil Engineering, Research Center for Eco-environmental Engineering, Dongguan University of Technology, Dongguan, Guangdong 523808, P. R. China
| | - Marc Robert
- School of Environment and Civil Engineering, Research Center for Eco-environmental Engineering, Dongguan University of Technology, Dongguan, Guangdong 523808, P. R. China
- Institut Universitaire de France (IUF), F-75005, Paris, France
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Ali E, Sayah MA, Dawood AAAS, Hamoody AHM, Hamoodah ZJ, Ramadan MF, Abbas HA, Alawadi A, Alsalamy A, Abbass R. CO 2 reduction reaction on Sc-doped nanocages as catalysts. J Mol Model 2023; 29:381. [PMID: 37985487 DOI: 10.1007/s00894-023-05776-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 10/31/2023] [Indexed: 11/22/2023]
Abstract
CONTEXT The catalytic ability of Sc-doped C46 and Sc-doped Al23P23 as catalysts of CO2-RR to create the CH4 and CH3OH is investigated. The mechanisms of CO2-RR are examined by theoretical methods and ΔGreaction of reaction steps of CO2-RR mechanisms are calculated. The overpotential of CH4 and CH3OH production on Sc-doped C46 and Sc-doped Al23P23 is calculated. The Sc atoms of Sc-doped C46 and Sc-doped Al23P23 can adsorb the CO2 molecule as the first step of CO2-RR. The CH4 is produced from hydrogenation of *CH3O and the *CO → *CHO reaction step is the rate limiting step for CH4 production. The CH3OH can be formed on Sc-doped C46 and Sc-doped Al23P23 by *CO → *CHO → *CH2O → *CH3O → CH3OH mechanism and HCOOH → *CHO → *CH2O → *CH3O → CH3OH mechanism. The Sc-C46 and Sc-Al23P23 can catalyze the CO2-RR to produce the CH4 and CH3OH by acceptable mechanisms. METHODS Here, the structures are optimized by PW91PW91/6-311+G (2d, 2p) and M06-2X/cc-pVQZ methods in GAMESS software. The frequencies of nanocages and their complexes with species of CO2-RR are investigated by mentioned methods. The transition state of each reaction step of CO2-RR is searched by Berny method to find the CO2-RR intermediates. The ∆Eadsorption of intermediates of CO2-RR on surfaces of nanocages is calculated and the ∆Greaction of reaction steps of CO2-RR is calculated.
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Affiliation(s)
- Eyhab Ali
- Al-Zahraa University for Women, Karbala, Iraq
| | | | | | | | | | | | - Hussein Abdullah Abbas
- College of Technical Engineering, National University of Science and Technology, Nasiriyah, Dhi Qar, Iraq
| | - Ahmed Alawadi
- College of Technical Engineering, The Islamic University, Najaf, Iraq
- College of Medical Technique, The Islamic University of Al Diwaniyah, Al Diwaniyah, Iraq
| | - Ali Alsalamy
- College of Technical Engineering, Imam Ja'afar Al-Sadiq University, Baghdad, Al-Muthanna, 66002, Iraq.
| | - Rathab Abbass
- Medical Technical College, Al-Farahidi University, Baghdad, Iraq
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4
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Palmese M, Pérez-Torrente JJ, Passarelli V. Reactivity of Ir(I)-aminophosphane platforms towards oxidants. Dalton Trans 2023; 52:13689-13703. [PMID: 37706349 DOI: 10.1039/d3dt02361c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
The iridium(I)-aminophosphane complex [Ir{κ3C,P,P'-(SiNP-H)}(cod)] has been prepared by reaction of [IrCl(cod)(SiNP)] with KCH3COO. DFT calculations show that this reaction takes place through an unexpected outer sphere mechanism (SiNP = SiMe2{N(4-C6H4Me)PPh2}2; SiNP-H = CH2SiMe{N(4-C6H4Me)PPh2}2). The reaction of [IrCl(cod)(SiNP)] or [Ir{κ3C,P,P'-(SiNP-H)}(cod)] with diverse oxidants has been explored, yielding a range of iridium(III) derivatives. On one hand, [IrCl(cod)(SiNP)] reacts with allyl chloride rendering the octahedral iridium(III) derivative [IrCl2(η3-C3H5)(SiNP)], which, in turn, reacts with tert-butyl isocyanide yielding the substitution product [IrCl(η3-C3H5)(CNtBu)(SiNP)]Cl via the observed intermediate [IrCl2(η1-C3H5)(CNtBu)(SiNP)]. On the other hand, the reaction of [Ir{κ3C,P,P'-(SiNP-H)}(cod)] with [FeCp2]X (X = PF6, CF3SO3), I2 or CF3SO3CH3 results in the metal-centered two-electron oxidation rendering a varied assortment of iridium(III) compounds. [Ir{κ3C,P,P'-(SiNP-H)}(cod)] reacts with [FeCp2]+ (1 : 2) in acetonitrile affording [Ir{κ3C,P,P'-(SiNP-H)}(CH3CN)3]2+ isolated as both the triflato and the hexafluorophosphato derivatives. Also, the reaction of [Ir{κ3C,P,P'-(SiNP-H)}(cod)] with I2 (1 : 1) yields a mixture of iridium(III) derivatives, namely the mononuclear compound [IrI(κ2P,P'-SiNP)(η2,η3-C8H11)]I, containing the η2,η3-cycloocta-2,6-dien-1-yl ligand, and two isomers of the dinuclear derivative [Ir2{κ3C,P,P'-(SiNP-H)}2(μ-I)3]I, the first species being isolated in low yield. DFT calculations indicate that [IrI(κ2P,P'-SiNP)(η2,η3-C8H11)]I forms as the result of a bielectronic oxidation of iridium(I) followed by the deprotonation of the cod ligand by iodide and the protonation of the methylene moiety of the [Ir{κ3C,P,P'-(SiNP-H)}] platform by the newly formed HI. Finally, the oxidation of [Ir{κ3C,P,P'-(SiNP-H)}(cod)] by methyl triflate proceeds via a hydride abstraction from the cod ligand, with the elimination of methane and the formation of the η2,η3-cycloocta-2,6-dien-1-yl ligand with the concomitant two-electron oxidation of the iridium centre. The crystal structures of selected compounds have been determined.
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Affiliation(s)
- Marco Palmese
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, ES-50009 Zaragoza, Spain.
| | - Jesús J Pérez-Torrente
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, ES-50009 Zaragoza, Spain.
| | - Vincenzo Passarelli
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, ES-50009 Zaragoza, Spain.
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5
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Smith MB. The Backbone of Success of P,N-Hybrid Ligands: Some Recent Developments. Molecules 2022; 27:6293. [PMID: 36234830 PMCID: PMC9614609 DOI: 10.3390/molecules27196293] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 09/21/2022] [Accepted: 09/21/2022] [Indexed: 12/03/2022] Open
Abstract
Organophosphorus ligands are an invaluable family of compounds that continue to underpin important roles in disciplines such as coordination chemistry and catalysis. Their success can routinely be traced back to facile tuneability thus enabling a high degree of control over, for example, electronic and steric properties. Diphosphines, phosphorus compounds bearing two separated PIII donor atoms, are also highly valued and impart their own unique features, for example excellent chelating properties upon metal complexation. In many classical ligands of this type, the backbone connectivity has been based on all carbon spacers only but there is growing interest in embedding other donor atoms such as additional nitrogen (-NH-, -NR-) sites. This review will collate some important examples of ligands in this field, illustrate their role as ligands in coordination chemistry and highlight some of their reactivities and applications. It will be shown that incorporation of a nitrogen-based group can impart unusual reactivities and important catalytic applications.
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Affiliation(s)
- Martin B Smith
- Department of Chemistry, Loughborough University, Loughborough, Leics LE11 3TU, UK
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6
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López-Estrada O, Torres-Moreno JL, Zuniga-Gutierrez B, Calaminici P, Malola S, Köster AM, Häkkinen H. 1H NMR global diatropicity in copper hydride complexes. NANOSCALE 2022; 14:12668-12676. [PMID: 35947047 DOI: 10.1039/d2nr02415b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Understanding the magnetic response of electrons in nanoclusters is essential to interpret their NMR spectra thereby providing guidelines for their synthesis towards various target applications. Here, we consider two copper hydride clusters that have applications in hydrogen storage and release under standard temperature and pressure. Through Born-Oppenheimer molecular dynamics simulations, we study dynamics effects and their contributions to the NMR peaks. Finally, we examine the electrons' magnetic response to an applied external magnetic field using the gauge-including magnetically induced currents theory. Local diatropic currents are generated in both clusters but an interesting global diatropic current also appears. This diatropic current has contributions from three μ3-H hydrides and six Cu atoms that form a chain together with three S atoms from the closest ligands resulting in a higher shielding of these hydrides' 1H NMR response. This explains the unusual upfield chemical shift compared to the common downfield shift in similarly coordinated hydrides both observed in previous experimental reports.
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Affiliation(s)
- Omar López-Estrada
- Department of Physics, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä, Finland
- Departamento de Química, Cinvestav, Av. Instituto Politécnico Nacional, 2508, A.P. 14740, Ciudad de México 07000, Mexico
| | - Jorge L Torres-Moreno
- Departamento de Química, Cinvestav, Av. Instituto Politécnico Nacional, 2508, A.P. 14740, Ciudad de México 07000, Mexico
| | - Bernardo Zuniga-Gutierrez
- Departamento de Química, Universidad de Guadalajara, CUCEI, Blvd. Marcelino García Barragán 1421, C. P. 44430 Guadalajara, Jalisco, Mexico
| | - Patrizia Calaminici
- Departamento de Química, Cinvestav, Av. Instituto Politécnico Nacional, 2508, A.P. 14740, Ciudad de México 07000, Mexico
| | - Sami Malola
- Department of Physics, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä, Finland
| | - Andreas M Köster
- Departamento de Química, Cinvestav, Av. Instituto Politécnico Nacional, 2508, A.P. 14740, Ciudad de México 07000, Mexico
| | - Hannu Häkkinen
- Department of Physics, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä, Finland
- Department of Chemistry, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä, Finland.
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Norwine EE, Kiernicki JJ, Zeller M, Szymczak NK. Distinct Reactivity Modes of a Copper Hydride Enabled by an Intramolecular Lewis Acid. J Am Chem Soc 2022; 144:15038-15046. [PMID: 35960993 PMCID: PMC10291504 DOI: 10.1021/jacs.2c02937] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We disclose a 1,4,7-triazacyclononane (TACN) ligand featuring an appended boron Lewis acid. Metalation with Cu(I) affords a series of tetrahedral complexes including a boron-capped cuprous hydride. We demonstrate distinct reactivity modes as a function of chemical oxidation: hydride transfer to CO2 in the copper(I) state and oxidant-induced H2 evolution as well as alkyne reduction.
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Affiliation(s)
- Emily E. Norwine
- University of Michigan, 930 N. University, Ann Arbor, MI 48109 (USA)
| | - John J. Kiernicki
- University of Michigan, 930 N. University, Ann Arbor, MI 48109 (USA)
| | - Matthias Zeller
- H. C. Brown Laboratory, Purdue University, 560 Oval Dr., West Lafayette, IN 47907 (USA)
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8
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Palmese M, Pérez-Torrente JJ, Passarelli V. Cyclometalated iridium complexes based on monodentate aminophosphanes. Dalton Trans 2022; 51:12334-12351. [PMID: 35904083 DOI: 10.1039/d2dt02081e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Monodentate aminophosphanes HNP [NH(4-tolyl)PPh2] and SiMe3NP [SiMe3N(4-tolyl)PPh2] react with [Ir(μ-Cl)(cod)]2 affording tetra- or pentacoordinate complexes of formula [IrCl(L)n(cod)] (L = HNP, n = 1, 2; L = SiMe3NP, n = 1). The reaction of [IrCl(SiMe3NP)(cod)] with carbon monoxide smoothly renders [Ir(CO)3(SiMe3NP)2][IrCl2(CO)2]. The reaction of HNP or SiMe3NP with [Ir(CH3CN)2(cod)][PF6] yields the cyclometalated iridium(III)-hydride derivatives [IrH{κ2C,P-NR(4-C6H3CH3)PPh2}(cod)(CH3CN)][PF6] (R = H, SiMe3) as a result of the intramolecular oxidative addition of the tolyl C2-H bond to iridium. The straighforward formation of [IrH{κ2C,P-SiMe3N(4-C6H3CH3)PPh2}(cod)(CH3CN)]+ was observed when the reaction was monitored by NMR spectroscopy at 233 K, whereas a more complex reaction sequence was observed in the formation of [IrH{κ2C,P-NH(4-C6H3CH3)PPh2}(cod)(CH3CN)]+, including the formation of [IrH{κ2C,P-NH(4-C6H3CH3)PPh2}(HNP)(cod)]+ and [Ir(cod)(HNP)2]+. The "mixed" complex [IrH{κ2C,P-SiMe3N(4-C6H3CH3)PPh2}(HNP)(cod)]+ was obtained upon reaction of [IrH{κ2C,P-NH(4-C6H3CH3)PPh2}(cod)(CH3CN)][PF6] with SiMe3NP at 233 K. Finally, the reaction of [Ir(CH3CN)2(coe)2][PF6] with SiMe3NP or HNP resulted in the formation of [Ir(CH3CN)2(SiMe3NP)2][PF6] and [IrH{κ2C,P-NH(4-C6H3CH3)PPh2}(HNP)2(CH3CN)][PF6], respectively. Both the OC-6-35 and the OC-6-52 isomers of [IrH{κ2C,P-NH(4-C6H3CH3)PPh2}(HNP)2(CH3CN)]+ - featuring facial and meridional dispositions of the phosphorus atoms, respectively - were isolated depending on the reaction solvent. Several compounds described herein catalyse the dehydrogenation of formic acid in DMF, [IrCl(HNP)2(cod)] being the most active, with TOF1 min of about 2300 h-1 (5 mol% catalyst, 50 mol% sodium formate, DMF, 80 °C).
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Affiliation(s)
- Marco Palmese
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, ES-50009 Zaragoza, Spain.
| | - Jesús J Pérez-Torrente
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, ES-50009 Zaragoza, Spain.
| | - Vincenzo Passarelli
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, ES-50009 Zaragoza, Spain.
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Pandey B, Krause JA, Guan H. Iron Dihydride Complex Stabilized by an All-Phosphorus-Based Pincer Ligand and Carbon Monoxide. Inorg Chem 2022; 61:11143-11155. [PMID: 35816559 DOI: 10.1021/acs.inorgchem.2c01027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PNP-pincer-stabilized iron carbonyl dihydride complexes are key intermediates in catalytic hydrogenation and dehydrogenation reactions; however, decomposition through these intermediates has been observed. This inspires the development of a PPP-pincer system that may show improved catalyst stability. In this work, bis[2-(diisopropylphosphino)phenyl]phosphine (or iPrPPHP) is used to react with FeCl2 under a carbon monoxide (CO) atmosphere to yield trans-(iPrPPHP)Fe(CO)Cl2. A subsequent reaction with NaBH4 produces syn/anti-(iPrPPHP)FeH(CO)Cl or cis,anti-(iPrPPHP)Fe(CO)H2, depending on the amount of NaBH4 employed. The cis-dihydride complex shows catalytic activity for the conversion of PhCHO to PhCH2OH (under H2) or PhCO2CH2Ph (under Ar). It also catalyzes the dehydrogenation of PhCH2OH to PhCHO and PhCO2CH2Ph, albeit with limited turnover numbers. A more efficient catalytic process is the dehydrogenation of formic acid to carbon dioxide (CO2), which can operate under additive-free conditions. Mechanistic investigation suggests that the cis-dihydride complex undergoes protonation with formic acid to release H2 while forming anti-(iPrPPHP)FeH(CO)(OCHO)·HCO2H, in which the CO ligand has shifted and the formate is hydrogen-bonded to formic acid. The hydrido formate complex loses CO2 under ambient conditions, completing the catalytic cycle by reforming the cis-dihydride complex.
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Affiliation(s)
- Bedraj Pandey
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
| | - Jeanette A Krause
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
| | - Hairong Guan
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
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10
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Palmese M, Pérez-Torrente JJ, Passarelli V. Synthesis and reactivity of an iridium complex based on a tridentate aminophosphano ligand. Dalton Trans 2022; 51:7142-7153. [PMID: 35466986 DOI: 10.1039/d2dt00794k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The iridium(III) hydride compound [IrH{κ3C,P,P'-(SiNP-H)}(CNtBu)2][PF6] (1PF6) was obtained by reaction of [Ir(SiNP)(cod)][PF6] with CNtBu as the result of the intramolecular oxidative addition of the SiCH2-H bond to iridium(I) [SiNP = Si(CH3)2{N(4-tolyl)PPh2}2, SiNP-H = CH2Si(CH3){N(4-tolyl)PPh2}2]. The mechanism of the reaction was investigated by NMR spectroscopy and DFT calculations showing that the pentacoordinated intermediate [Ir(SiNP)(cod)(CNtBu)][PF6] (2PF6) forms in the first place and that further reacts with CNtBu, affording the square planar intermediate [Ir(SiNP)(CNtBu)2][PF6] (3PF6) that finally undergoes the intramolecular oxidative addition of the SiCH2-H bond. The reactivity of 1PF6 was investigated. On one hand, the reaction of 1PF6 with N-chlorosuccinimide or N-bromosuccinimide provides the haloderivatives [IrX{κ3C,P,P'-(SiNP-H)}(CNtBu)2][PF6] (X = Cl, 4PF6; Br, 5PF6), and the reaction of 5PF6 with AgPF6 in the presence of acetonitrile affords the solvato species [Ir{κ3C,P,P'-(SiNP-H)}(CH3CN)(CNtBu)2]2+ (62+) isolated as the hexafluorophosphate salt. On the other hand, the reaction of 1PF6 with HBF4 gives the iridium(III) compound [IrH(CH2SiF2CH3)(HNP)2(CNtBu)2][BF4] (7BF4) as the result of the formal addition of hydrogen fluoride to the Si-N bonds of 1+ [HNP = HN(4-tolyl)PPh2]. A similar outcome was observed in the reaction of 1PF6 with CF3COOH rendering 7PO2F2. In this case the intermediate [IrH{κ2C,P-CH2SiMeFN(4-tolyl)PPh2}(HNP)(CNtBu)2]+ (8+) was observed and characterised in situ by NMR spectroscopy. DFT calculations suggests that the reaction goes through the sequential protonation of the nitrogen atom of the Si-N-P moiety followed by the formal addition of fluoride ion to silicon. Also, the crystal structures of SiNP, 1PF6, 4PF6 and 7BF4 have been determined by X-ray diffraction measurements.
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Affiliation(s)
- Marco Palmese
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catalisis Homogenea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, ES-50007 Zaragoza, Spain.
| | - Jesús J Pérez-Torrente
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catalisis Homogenea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, ES-50007 Zaragoza, Spain.
| | - Vincenzo Passarelli
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catalisis Homogenea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, ES-50007 Zaragoza, Spain.
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