1
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Choi H, Yoo S, Song H, Lee E. IZCp and PZCp: Redox Non-innocent Cyclopentadienyl Ligands as Electron Reservoirs for Sandwich Complexes. Inorg Chem 2024; 63:6427-6434. [PMID: 38534011 DOI: 10.1021/acs.inorgchem.4c00259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
A long-sustained effort of systematic steric and electronic modification of cyclopentadienyl (Cp) ligands has enabled them to find wide-ranging, valuable applications. Herein, we present two novel Cp ligands: imidazolium- and pyrrolinium-substituted zwitterionic Cps (IZCp and PZCp), whose key utility is redox non-innocence─the ability to participate cooperatively with the metal center in redox reactions. Through the simple metalation of ZCps, the Cr(0) and Mo(0) half-sandwich complexes (IZCp)Cr(CO)3, (PZCp)Cr(CO)3, (IZCp)Mo(CO)3, and (PZCp)Mo(CO)3, respectively, as well as the Ru(II) sandwich complexes [(IZCp)RuCp]PF6 and [(PZCp)RuCp]PF6 were prepared. The sandwich complexes were fully characterized and showed by cyclic voltammetry reversible one-electron reduction at E1/2 potentials ranging from -1.7 to -2.7 V vs Fc/Fc+. These values are unusually low and have not been observed with other Cp ligands due to the instability of the reduced complexes. Density functional theory (DFT) calculations for the reduced sandwich derivatives with IZCp and PZCp showed their spin densities to be highly delocalized over their ZCp ligand moieties (70-90%). Electron paramagnetic resonance (EPR) analysis of the isolated K[(PZCp)Mo(CO)3] and (PZCp)RuCp also indicated a high degree of ligand-localized radical character. Thus, the IZCp and PZCp ligands act as electron reservoirs to sustain these sandwich complexes in highly reduced states. At the same time, the CO stretching frequencies of K[(PZCp)Mo(CO)3]: νCO 1871, 1748, and 1699 cm-1, rank the [PZCp]- ligand as the strongest electron-donating Cp ligand among the reported CpMo(CO)3 derivatives, whose νCO > 1746 cm-1. In addition, these redox non-innocent Cps were obtained in high yields and found to be practically air- and moisture-stable, unlike typical Cps.
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Affiliation(s)
- Hyeonjeong Choi
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Seunghyuk Yoo
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Hayoung Song
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Eunsung Lee
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
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2
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Montgomery CL, Amtawong J, Jordan AM, Kurtz DA, Dempsey JL. Proton transfer kinetics of transition metal hydride complexes and implications for fuel-forming reactions. Chem Soc Rev 2023; 52:7137-7169. [PMID: 37750006 DOI: 10.1039/d3cs00355h] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Proton transfer reactions involving transition metal hydride complexes are prevalent in a number of catalytic fuel-forming reactions, where the proton transfer kinetics to or from the metal center can have significant impacts on the efficiency, selectivity, and stability associated with the catalytic cycle. This review correlates the often slow proton transfer rate constants of transition metal hydride complexes to their electronic and structural descriptors and provides perspective on how to exploit these parameters to control proton transfer kinetics to and from the metal center. A toolbox of techniques for experimental determination of proton transfer rate constants is discussed, and case studies where proton transfer rate constant determination informs fuel-forming reactions are highlighted. Opportunities for extending proton transfer kinetic measurements to additional systems are presented, and the importance of synergizing the thermodynamics and kinetics of proton transfer involving transition metal hydride complexes is emphasized.
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Affiliation(s)
- Charlotte L Montgomery
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
| | - Jaruwan Amtawong
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
| | - Aldo M Jordan
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
| | - Daniel A Kurtz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
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3
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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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4
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VanderWeide A, Prokopchuk DE. Cyclopentadienyl ring activation in organometallic chemistry and catalysis. Nat Rev Chem 2023:10.1038/s41570-023-00501-1. [PMID: 37258685 DOI: 10.1038/s41570-023-00501-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2023] [Indexed: 06/02/2023]
Abstract
The cyclopentadienyl (Cp) ligand is a cornerstone of modern organometallic chemistry. Since the discovery of ferrocene, the Cp ligand and its various derivatives have become foundational motifs in catalysis, medicine and materials science. Although largely considered an ancillary ligand for altering the stereoelectronic properties of transition metal centres, there is mounting evidence that the core Cp ring structure also serves as a reservoir for reactive protons (H+), hydrides (H-) or radical hydrogen (H•) atoms. This Review chronicles the field of Cp ring activation, highlighting the pivotal role that Cp ligands can have in electrocatalytic H2 production, N2 reduction, hydride transfer reactions and proton-coupled electron transfer.
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5
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Henke W, Peng Y, Meier A, Fujita E, Grills D, Polyansky D, Blakemore J. Mechanistic roles of metal- and ligand-protonated species in hydrogen evolution with [Cp*Rh] complexes. Proc Natl Acad Sci U S A 2023; 120:e2217189120. [PMID: 37186841 PMCID: PMC10214172 DOI: 10.1073/pnas.2217189120] [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: 10/07/2022] [Accepted: 02/17/2023] [Indexed: 05/17/2023] Open
Abstract
Protonation reactions involving organometallic complexes are ubiquitous in redox chemistry and often result in the generation of reactive metal hydrides. However, some organometallic species supported by η5-pentamethylcyclopentadienyl (Cp*) ligands have recently been shown to undergo ligand-centered protonation by direct proton transfer from acids or tautomerization of metal hydrides, resulting in the generation of complexes bearing the uncommon η4-pentamethylcyclopentadiene (Cp*H) ligand. Here, time-resolved pulse radiolysis (PR) and stopped-flow spectroscopic studies have been applied to examine the kinetics and atomistic details involved in the elementary electron- and proton-transfer steps leading to complexes ligated by Cp*H, using Cp*Rh(bpy) as a molecular model (where bpy is 2,2'-bipyridyl). Stopped-flow measurements coupled with infrared and UV-visible detection reveal that the sole product of initial protonation of Cp*Rh(bpy) is [Cp*Rh(H)(bpy)]+, an elusive hydride complex that has been spectroscopically and kinetically characterized here. Tautomerization of the hydride leads to the clean formation of [(Cp*H)Rh(bpy)]+. Variable-temperature and isotopic labeling experiments further confirm this assignment, providing experimental activation parameters and mechanistic insight into metal-mediated hydride-to-proton tautomerism. Spectroscopic monitoring of the second proton transfer event reveals that both the hydride and related Cp*H complex can be involved in further reactivity, showing that [(Cp*H)Rh] is not necessarily an off-cycle intermediate, but, instead, depending on the strength of the acid used to drive catalysis, an active participant in hydrogen evolution. Identification of the mechanistic roles of the protonated intermediates in the catalysis studied here could inform design of optimized catalytic systems supported by noninnocent cyclopentadienyl-type ligands.
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Affiliation(s)
- Wade C. Henke
- Department of Chemistry, University of Kansas, Lawrence, KS66045
| | - Yun Peng
- Department of Chemistry, University of Kansas, Lawrence, KS66045
| | - Alex A. Meier
- Department of Chemistry, University of Kansas, Lawrence, KS66045
| | - Etsuko Fujita
- Chemistry Division, Brookhaven National Laboratory, Upton, NY11973-5000
| | - David C. Grills
- Chemistry Division, Brookhaven National Laboratory, Upton, NY11973-5000
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6
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Boekell NG, Bartulovich CO, Maity S, Flowers RA. Accessing Unusual Reactivity through Chelation-Promoted Bond Weakening. Inorg Chem 2023; 62:5040-5045. [PMID: 36912617 DOI: 10.1021/acs.inorgchem.3c00298] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Highly reducing Sm(II) reductants and protic ligands were used as a platform to ascertain the relationship between low-valent metal-protic ligand affinity and degree of ligand X-H bond weakening with the goal of forming potent proton-coupled electron transfer (PCET) reductants. Among the Sm(II)-protic ligand reductant systems investigated, the samarium dibromide N-methylethanolamine (SmBr2-NMEA) reagent system displayed the best combination of metal-ligand affinity and stability against H2 evolution. The use of SmBr2-NMEA afforded the reduction of a range of substrates that are typically recalcitrant to single-electron reduction including alkynes, lactones, and arenes as stable as biphenyl. Moreover, the unique role of NMEA as a chelating ligand for Sm(II) was demonstrated by the reductive cyclization of unactivated esters bearing pendant olefins in contrast to the SmBr2-water-amine system. Finally, the SmBr2-NMEA reagent system was found to reduce substrates analogous to key intermediates in the nitrogen fixation process. These results reveal SmBr2-NMEA to be a powerful reductant for a wide range of challenging substrates and demonstrate the potential for the rational design of PCET reagents with exceptionally weak X-H bonds.
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Affiliation(s)
- Nicholas G Boekell
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Caroline O Bartulovich
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Sandeepan Maity
- Department of Chemistry, C. V. Raman Global University, Bhubaneswar, Odisha 752054, India
| | - Robert A Flowers
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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7
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Pal S. Cp* non-innocence and the implications of (η 4-Cp*H)Rh intermediates in the hydrogenation of CO 2, NAD +, amino-borane, and the Cp* framework - a computational study. Dalton Trans 2023; 52:1182-1187. [PMID: 36648493 DOI: 10.1039/d2dt03611h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In hydrogenation mediated by half-sandwich complexes of Rh, Cp*Rh(III)-H intermediates are critical hydride-delivery agents. For bipyridine-supported complexes, a unique transformation named 'Cp* non-innocence' leads to the appearance of (Cp*H)Rh(I) intermediates, which are purported to exhibit enhanced hydride-delivery capabilities. In this work, DFT calculations performed to compare the role of these complexes in hydrogenation reveal that (Cp*H)Rh(I) intermediates do not compete with the conventional pathway (involving Cp*Rh(III)-H); instead they can lead to sequential hydrogenation of the Cp* framework, and potentially, catalyst degradation. Thus, caution is warranted when invoking the truly homogeneous nature of hydrogenation catalysis mediated by this popular class of complexes.
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Affiliation(s)
- Shrinwantu Pal
- Coordination Chemistry and Catalysis Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Okinawa, 904-0495, Japan.
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8
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Boyd EA, Peters JC. Sm(II)-Mediated Proton-Coupled Electron Transfer: Quantifying Very Weak N-H and O-H Homolytic Bond Strengths and Factors Controlling Them. J Am Chem Soc 2022; 144:21337-21346. [PMID: 36346706 PMCID: PMC10281198 DOI: 10.1021/jacs.2c09580] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Coordination of alcohols to the single-electron reductant samarium diiodide (SmI2) results in substantial O-H bond weakening, affording potent proton-coupled electron transfer (PCET) reagents. However, poorly defined speciation of SmI2 in tetrahydrofuran (THF)/alcohol mixtures limits reliable thermodynamic analyses of such systems. Rigorous determination of bond dissociation free energy (BDFE) values in such Sm systems, important to evaluating their reactivity profiles, motivates studies of model Sm systems where contributing factors can be teased apart. Here, a bulky and strongly chelating macrocyclic ligand ((tBu2ArOH)2Me2cyclam) maintains solubility, eliminates dimerization pathways, and facilitates clean electrochemical behavior in a well-defined functional model for the PCET reactivity of SmII with coordinating proton sources. Direct measurement of thermodynamic parameters enables reliable experimental estimation of the BDFEs in 2-pyrrolidone and MeOH complexes of ((tBu2ArO)2Me2cyclam)SmII, thereby revealing exceptionally weak N-H and O-H BDFEs of 27.2 and <24.1 kcal mol-1, respectively. Expanded thermochemical cycles reveal that this bond weakening stems from the very strongly reducing SmII center and the formation of strong SmIII-alkoxide (and -pyrrolidonate) interactions in the PCET products. We provide a detailed analysis comparing these BDFE values with those that have been put forward for SmI2 in THF in the presence of related proton donors. We suggest that BDFE values for the latter systems may in fact be appreciably higher than the system described herein. Finally, protonation and electrochemical reduction steps necessary for the regeneration of the PCET donors from SmIII-alkoxides are demonstrated, pointing to future strategies aimed at achieving (electro)catalytic turnover using SmII-based PCET reagents.
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Affiliation(s)
- Emily A Boyd
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
| | - Jonas C Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
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9
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Kim S, Kim J, Zhong H, Panetti GB, Chirik PJ. Catalytic N–H Bond Formation Promoted by a Ruthenium Hydride Complex Bearing a Redox-Active Pyrimidine-Imine Ligand. J Am Chem Soc 2022; 144:20661-20671. [DOI: 10.1021/jacs.2c07800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Sangmin Kim
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Junho Kim
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Hongyu Zhong
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Grace B. Panetti
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J. Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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10
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Abstract
Coordination-induced bond weakening is a phenomenon wherein ligand X-H bond homolysis occurs in concert with the energetically favorable oxidation of a coordinating metal complex. The coupling of these two processes enables thermodynamically favorable proton-coupled electron transfer reductions to form weak bonds upon formal hydrogen atom transfer to substrates. Moreover, systems utilizing coordination-induced bond weakening have been shown to facilitate the dehydrogenation of feedstock molecules including water, ammonia, and primary alcohols under mild conditions. The formation of exceptionally weak substrate X-H bonds via small molecule homolysis is a powerful strategy in synthesis and has been shown to enable nitrogen fixation under mild conditions. Coordination-induced bond weakening has also been identified as an integral process in biophotosynthesis and has promising applications in renewable chemical fuel storage systems. This review presents a discussion of the advances made in the study of coordination-induced bond weakening to date. Because of the broad range of metal and ligand species implicated in coordination-induced bond weakening, each literature report is discussed individually and ordered by the identity of the low-valent metal. We then offer mechanistic insights into the basis of coordination-induced bond weakening and conclude with a discussion of opportunities for further research into the development and applications of coordination-induced bond weakening systems.
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Affiliation(s)
- Nicholas G Boekell
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Robert A Flowers
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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11
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Abstract
Phosphorus mononitride (PN) only has a fleeting existence on Earth, and molecular precursors for the release of this molecule under mild conditions in solution have remained elusive. Here we report the synthesis of an anthracene-based precursor-an anthracene moiety featuring an azidophosphine bridge across its central ring-that dissociates into dinitrogen, anthracene and P≡N in solution with a first-order half-life of roughly 30 min at room temperature. Heated under reduced pressure, this azidophosphine-anthracene precursor decomposes in an explosive fashion at around 42 °C, as demonstrated in a molecular-beam mass spectrometry study. The precursor is also shown to serve as a PN transfer reagent in the synthesis of an Fe-NP coordination complex, through ligand exchange with its Fe-N2 counterpart. The terminal N-bonded complex was found to be energetically preferred, compared to its P-bonded linkage isomer, owing to a significant covalent Fe-pnictogen bond character and an associated less unfavourable Pauli repulsion in the metal-ligand interaction.
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12
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Regenauer NI, Wadepohl H, Roşca DA. Metal-Ligand Cooperativity in Iron Dinitrogen Complexes: Proton-Coupled Electron Transfer Disproportionation and an Anionic Fe(0)N 2 Hydride. Inorg Chem 2022; 61:7426-7435. [PMID: 35508073 DOI: 10.1021/acs.inorgchem.2c00459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Metal-ligand cooperativity and redox-active ligands enable the use of open-shell first-row transition metals in catalysis. However, the fleeting nature of the reactive intermediates prevents direct inspection of the relevant catalytic species. By employing phosphine α-iminopyridine (PNN)-based complexes, we show that chemical and redox metal-ligand cooperativity can be combined in the coordination sphere of iron dinitrogen complexes. These systems show dual activation modes either through deprotonation, which triggers reversible core dearomatization, or through reversibly accepting one electron by reducing the imine functionality. (PNN)Fe(N2) fragments can be obtained under mildly reducing conditions. Deprotonation of such complexes induces dearomatization of the pyridine core while retaining a terminally coordinated N2 ligand. This species is nevertheless stable in solution only below -30 °C and undergoes unusual ligand-assisted redox disproportionation through proton-coupled electron transfer at room temperature. The origin of this phenomenon is the significant lability of the α-imine C-H bonds in the dearomatized species, where the calculated bond dissociation free energy is 48.7 kcal mol-1. The dispropotionation reaction yields an overreduced iron compound, demonstrating that the formation of such species can be triggered by mild bases, and does not require harsh reducing agents. Reaction of the dearomatized species with dihydrogen yields a rare anionic Fe hydride that binds dinitrogen and features a rearomatized core.
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Affiliation(s)
- Nicolas I Regenauer
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
| | - Dragoş-Adrian Roşca
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
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13
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Zurakowski JA, Austen B, Brown KC, Drover MW. Bis(1-Bora-4-phosphorinane) Ring Closure at Cp*M (M = Fe, Co) Complexes. Chem Commun (Camb) 2022; 58:2500-2503. [DOI: 10.1039/d1cc07060f] [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
Bis(1-bora-4-phosphorinane) metal complexes have been synthesized using a Cp*M-protecting (M = Fe, Co, Cp* = C5Me5-) strategy and structurally authenticated by NMR spectroscopy and single crystal X-ray diffraction. Synthesis of...
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14
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Sánchez P, Goel B, Neugebauer H, Lalancette RA, Grimme S, Hansen A, Prokopchuk DE. Ligand Protonation at Carbon, not Nitrogen, during H 2 Production with Amine-Rich Iron Electrocatalysts. Inorg Chem 2021; 60:17407-17413. [PMID: 34735115 DOI: 10.1021/acs.inorgchem.1c03142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We present monometallic H2 production electrocatalysts containing electron-rich triamine-cyclopentadienyl (Cp) ligands coordinated to iron. After selective CO extrusion from the iron tricarbonyl precursors, electrocatalysis is observed via cyclic voltammetry in the presence of an exogenous acid. Contrary to the fact that amines in the secondary coordination sphere are often protonated during electrocatalysis, comprehensive quantum-chemical calculations indicate that the amines likely do not function as proton relays; instead, endo-Cp ring protonation is most favorable after 1e- reduction. This unusual mechanistic pathway emphasizes the need to consider a broad domain of H+/e- addition products by synergistically combining experimental and theoretical resources.
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Affiliation(s)
- Práxedes Sánchez
- Department of Chemistry, Rutgers University─Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Bhumika Goel
- Department of Chemistry, Rutgers University─Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Hagen Neugebauer
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms Universität Bonn, Beringstraße 4, Bonn 53115, Germany
| | - Roger A Lalancette
- Department of Chemistry, Rutgers University─Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms Universität Bonn, Beringstraße 4, Bonn 53115, Germany
| | - Andreas Hansen
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms Universität Bonn, Beringstraße 4, Bonn 53115, Germany
| | - Demyan E Prokopchuk
- Department of Chemistry, Rutgers University─Newark, 73 Warren Street, Newark, New Jersey 07102, United States
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15
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Schneck F, Finger M, Siewert I, Schneider S. Solvent dependent C−H Bond Strength in a Nickel Pincer Complex. Z Anorg Allg Chem 2021. [DOI: 10.1002/zaac.202100077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Felix Schneck
- Universität Göttingen Institut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Markus Finger
- Universität Göttingen Institut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Inke Siewert
- Universität Göttingen Institut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Sven Schneider
- Universität Göttingen Institut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
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16
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Jaiswal K, Malik N, Tumanskii B, Ménard G, Dobrovetsky R. Carborane Stabilized "19-Electron" Molybdenum Metalloradical. J Am Chem Soc 2021; 143:9842-9848. [PMID: 34160218 PMCID: PMC8397321 DOI: 10.1021/jacs.1c03568] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Paramagnetic metal complexes gained
a lot of attention due to their
participation in a number of important chemical reactions. In most
cases, these complexes are dominated by 17-e metalloradicals that
are associatively activated with highly reactive paramagnetic 19-e
species. Molybdenum paramagnetic complexes are among the most investigated
ones. While some examples of persistent 17-e Mo-centered radicals
have been reported, in contrast, 19-e Mo-centered radicals are illusive
species and as such could rarely be detected. In this work, the photodissociation
of the [Cp(CO)3Mo]2 dimer (1) in
the presence of phosphines was revisited. As a result, the first persistent,
formally 19-e Mo radical with significant electron density on the
Mo center (22%), Cp(CO)3Mo•PPh2(o-C2B10H11) (5b), was generated and characterized by EPR
spectroscopy and MS as well as studied by DFT calculations. The stabilization
of 5b was likely achieved due to a unique electron-withdrawing
effect of the o-carboranyl substituent at the phosphorus
center.
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Affiliation(s)
- Kuldeep Jaiswal
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Naveen Malik
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Boris Tumanskii
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Gabriel Ménard
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Roman Dobrovetsky
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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17
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Zurakowski JA, Austen BJH, Drover MW. Wrapping Rhodium in a Borane Canopy: Implications for Hydride Formation and Transfer. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00194] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joseph A. Zurakowski
- Department of Chemistry and Biochemistry, The University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
| | - Brady J. H. Austen
- Department of Chemistry and Biochemistry, The University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
| | - Marcus W. Drover
- Department of Chemistry and Biochemistry, The University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
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18
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Nijamudheen A, Kanega R, Onishi N, Himeda Y, Fujita E, Ertem MZ. Distinct Mechanisms and Hydricities of Cp*Ir-Based CO 2 Hydrogenation Catalysts in Basic Water. ACS Catal 2021. [DOI: 10.1021/acscatal.0c04772] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- A. Nijamudheen
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Ryoichi Kanega
- Research Institute of Energy Conservation, Department of Energy and Environment, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan
| | - Naoya Onishi
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8569, Japan
| | - Yuichiro Himeda
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8569, Japan
| | - Etsuko Fujita
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Mehmed Z. Ertem
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
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Kurtz DA, Dhar D, Elgrishi N, Kandemir B, McWilliams SF, Howland WC, Chen CH, Dempsey JL. Redox-Induced Structural Reorganization Dictates Kinetics of Cobalt(III) Hydride Formation via Proton-Coupled Electron Transfer. J Am Chem Soc 2021; 143:3393-3406. [DOI: 10.1021/jacs.0c11992] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Daniel A. Kurtz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Debanjan Dhar
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Noémie Elgrishi
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
- Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, Louisiana 70803, United States
| | - Banu Kandemir
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Sean F. McWilliams
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - William C. Howland
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Chun-Hsing Chen
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Jillian L. Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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