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Imperato M, Nicolini A, Boniburini M, Sartini D, Benassi E, Chiesa M, Gigli L, Liao YK, Raza A, Salvadori E, Sorace L, Cornia A. Dual Structure of a Vanadyl-Based Molecular Qubit Containing a Bis(β-diketonato) Ligand. Inorg Chem 2024; 63:7912-7925. [PMID: 38620046 DOI: 10.1021/acs.inorgchem.4c00834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
We designed [VO(bdhb)] (1') as a new electronic qubit containing an oxovanadium(IV) ion (S = 1/2) embraced by a single bis(β-diketonato) ligand [H2bdhb = 1,3-bis(3,5-dioxo-1-hexyl)benzene]. The synthesis afforded three different crystal phases, all of which unexpectedly contain dimers with formula [(VO)2(bdhb)2] (1). A trigonal form (1h) with a honeycomb structure and 46% of solvent-accessible voids quantitatively transforms over time into a monoclinic solvatomorph 1m and minor amounts of a triclinic solventless phase (1a). In a static magnetic field, 1h and 1m have detectably slow magnetic relaxation at low temperatures through quantum tunneling and Raman mechanisms. Angle-resolved electron paramagnetic resonance (EPR) spectra on single crystals revealed signatures of low-dimensional magnetic behavior, which is solvatomorph-dependent, being the closest interdimer V···V separations (6.7-7.5 Å) much shorter than intramolecular V···V distances (11.9-12.1 Å). According to 1H diffusion ordered spectroscopy (DOSY) and EPR experiments, the complex adopts the desired monomeric structure in organic solution and its geometry was inferred from density functional theory (DFT) calculations. Spin relaxation measurements in a frozen toluene-d8/CD2Cl2 matrix yielded Tm values reaching 13 μs at 10 K, and coherent spin manipulations were demonstrated by Rabi nutation experiments at 70 K. The neutral quasi-macrocyclic structure, featuring nuclear spin-free donors and additional possibilities for chemical functionalization, makes 1' a new convenient spin-coherent building block in quantum technologies.
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Affiliation(s)
- Manuel Imperato
- Dipartimento di Scienze Chimiche e Geologiche e UdR INSTM, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 213/A, 41125 Modena, Italy
| | - Alessio Nicolini
- Dipartimento di Scienze Chimiche e Geologiche e UdR INSTM, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
| | - Matteo Boniburini
- Dipartimento di Scienze Chimiche e Geologiche e UdR INSTM, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
| | - Daniele Sartini
- Dipartimento di Chimica "Ugo Schiff" e UdR INSTM, Università degli Studi di Firenze, via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy
| | - Enrico Benassi
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 213/A, 41125 Modena, Italy
| | - Mario Chiesa
- Dipartimento di Chimica e NIS Centre, Università degli Studi di Torino, via P. Giuria 7, 10125 Torino, Italy
| | - Lara Gigli
- Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14 - km 163.5 in AREA Science Park, 34149 Basovizza (TS), Italy
| | - Yu-Kai Liao
- Dipartimento di Chimica e NIS Centre, Università degli Studi di Torino, via P. Giuria 7, 10125 Torino, Italy
| | - Arsen Raza
- Dipartimento di Chimica "Ugo Schiff" e UdR INSTM, Università degli Studi di Firenze, via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy
| | - Enrico Salvadori
- Dipartimento di Chimica e NIS Centre, Università degli Studi di Torino, via P. Giuria 7, 10125 Torino, Italy
| | - Lorenzo Sorace
- Dipartimento di Chimica "Ugo Schiff" e UdR INSTM, Università degli Studi di Firenze, via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy
| | - Andrea Cornia
- Dipartimento di Scienze Chimiche e Geologiche e UdR INSTM, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
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Mills LR, Simmons EM, Lee H, Nester E, Kim J, Wisniewski SR, Pecoraro MV, Chirik PJ. (Phenoxyimine)nickel-Catalyzed C(sp 2)-C(sp 3) Suzuki-Miyaura Cross-Coupling: Evidence for a Recovering Radical Chain Mechanism. J Am Chem Soc 2024; 146:10124-10141. [PMID: 38557045 DOI: 10.1021/jacs.4c01474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Phenoxyimine (FI)-nickel(II)(2-tolyl)(DMAP) compounds were synthesized and evaluated as precatalysts for the C(sp2)-C(sp3) Suzuki-Miyaura cross coupling of (hetero)arylboronic acids with alkyl bromides. With 5 mol % of the optimal (MeOMeFI)Ni(Aryl)(DMAP) precatalyst, the scope of the cross-coupling reaction was established and included a variety of (hetero)arylboronic acids and alkyl bromides (>50 examples, 33-97% yield). A β-hydride elimination-reductive elimination sequence from reaction with potassium isopropoxide base, yielding a potassium (FI)nickel(0)ate, was identified as a catalyst activation pathway that is responsible for halogen atom abstraction from the alkyl bromide. A combination of NMR and EPR spectroscopies identified (FI)nickel(II)-aryl complexes as the resting state during catalysis with no evidence for long-lived organic radical or odd-electron nickel intermediates. These data establish that the radical chain is short-lived and undergoes facile termination and also support a "recovering radical chain" process whereby the (FI)nickel(II)-aryl compound continually (re)initiates the radical chain. Kinetic studies established that the rate of C(sp2)-C(sp3) product formation was proportional to the concentration of the (FI)nickel(II)-aryl resting state that captures the alkyl radical for chain propagation. The proposed mechanism involves two key and concurrently operating catalytic cycles; the first involving a nickel(I/II/III) radical propagation cycle consisting of radical capture at (FI)nickel(II)-aryl, C(sp2)-C(sp3) reductive elimination, bromine atom abstraction from C(sp3)-Br, and transmetalation; and the second involving an off-cycle catalyst recovery process by slow (FI)nickel(II)-aryl → (FI)nickel(0)ate conversion for nickel(I) regeneration.
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Affiliation(s)
- L Reginald Mills
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Eric M Simmons
- Chemical Process Development, Bristol Myers Squibb Company, New Brunswick, New Jersey 08903, United States
| | - Heejun Lee
- Chemical Process Development, Bristol Myers Squibb Company, New Brunswick, New Jersey 08903, United States
| | - Eva Nester
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Junho Kim
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Steven R Wisniewski
- Chemical Process Development, Bristol Myers Squibb Company, New Brunswick, New Jersey 08903, United States
| | - Matthew V Pecoraro
- 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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3
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Imperato M, Nicolini A, Borsari M, Briganti M, Chiesa M, Liao YK, Ranieri A, Raza A, Salvadori E, Sorace L, Cornia A. Quantum spin coherence and electron spin distribution channels in vanadyl-containing lantern complexes. Inorg Chem Front 2023; 11:186-195. [PMID: 38221947 PMCID: PMC10782212 DOI: 10.1039/d3qi01806g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/02/2023] [Indexed: 01/16/2024]
Abstract
We herein investigate the heterobimetallic lantern complexes [PtVO(SOCR)4] as charge neutral electronic qubits based on vanadyl complexes (S = 1/2) with nuclear spin-free donor atoms. The derivatives with R = Me (1) and Ph (2) give highly resolved X-band EPR spectra in frozen CH2Cl2/toluene solution, which evidence the usual hyperfine coupling with the 51V nucleus (I = 7/2) and an additional superhyperfine interaction with the I = 1/2 nucleus of the 195Pt isotope (natural abundance ca. 34%). DFT calculations ascribe the spin density delocalization on the Pt2+ ion to a combination of π and δ pathways, with the former representing the predominant channel. Spin relaxation measurements in frozen CD2Cl2/toluene-d8 solution between 90 and 10 K yield Tm values (1-6 μs in 1 and 2-11 μs in 2) which compare favorably with those of known vanadyl-based qubits in similar matrices. Coherent spin manipulations indeed prove possible at 70 K, as shown by the observation of Rabi oscillations in nutation experiments. The results indicate that the heavy Group 10 metal ion is not detrimental to the coherence properties of the vanadyl moiety and that Pt-VO lanterns can be used as robust spin-coherent building blocks in materials science and quantum technologies.
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Affiliation(s)
- Manuel Imperato
- Dipartimento di Scienze Chimiche e Geologiche e UdR INSTM, Università degli Studi di Modena e Reggio Emilia via G. Campi 103 41125 Modena Italy
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia via G. Campi 213/A 41125 Modena Italy
| | - Alessio Nicolini
- Dipartimento di Scienze Chimiche e Geologiche e UdR INSTM, Università degli Studi di Modena e Reggio Emilia via G. Campi 103 41125 Modena Italy
| | - Marco Borsari
- Dipartimento di Scienze Chimiche e Geologiche e UdR INSTM, Università degli Studi di Modena e Reggio Emilia via G. Campi 103 41125 Modena Italy
| | - Matteo Briganti
- Dipartimento di Chimica "Ugo Schiff" e UdR INSTM, Università degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino FI Italy
| | - Mario Chiesa
- Dipartimento di Chimica e NIS Centre, Università degli Studi di Torino via P. Giuria 7 10125 Torino Italy
| | - Yu-Kai Liao
- Dipartimento di Chimica e NIS Centre, Università degli Studi di Torino via P. Giuria 7 10125 Torino Italy
| | - Antonio Ranieri
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia via G. Campi 103 41125 Modena Italy
| | - Arsen Raza
- Dipartimento di Chimica "Ugo Schiff" e UdR INSTM, Università degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino FI Italy
| | - Enrico Salvadori
- Dipartimento di Chimica e NIS Centre, Università degli Studi di Torino via P. Giuria 7 10125 Torino Italy
| | - Lorenzo Sorace
- Dipartimento di Chimica "Ugo Schiff" e UdR INSTM, Università degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino FI Italy
| | - Andrea Cornia
- Dipartimento di Scienze Chimiche e Geologiche e UdR INSTM, Università degli Studi di Modena e Reggio Emilia via G. Campi 103 41125 Modena Italy
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Mills LR, Gygi D, Simmons EM, Wisniewski SR, Kim J, Chirik PJ. Mechanistic Investigations of Phenoxyimine-Cobalt(II)-Catalyzed C(sp 2)-C(sp 3) Suzuki-Miyaura Cross-Coupling. J Am Chem Soc 2023; 145:17029-17041. [PMID: 37490763 DOI: 10.1021/jacs.3c02103] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
The mechanism of phenoxyimine (FI)-cobalt-catalyzed C(sp2)-C(sp3) Suzuki-Miyaura cross-coupling was studied using a combination of kinetic measurements and catalytic and stoichiometric experiments. A series of dimeric (FI)cobalt(II) bromide complexes, [(4-CF3PhFI)CoBr]2, [(4-OMePhFI)CoBr]2, and [(2,6-diiPrPhFI)CoBr]2, were isolated and characterized by 1H and 19F NMR spectroscopies, solution and solid-state magnetic susceptibility, electron paramagnetic resonance (EPR) spectroscopy, X-ray crystallography, and diffusion-ordered NMR spectroscopy (DOSY). One complex, [(4-CF3PhFI)CoBr]2, was explored as a single-component precatalyst for C(sp2)-C(sp3) Suzuki-Miyaura cross-coupling. Addition of potassium methoxide to [(4-CF3PhFI)CoBr]2 generated the corresponding (FI)cobalt(II) methoxide complex as determined by 1H and 19F NMR and EPR spectroscopies. These spectroscopic signatures were used to identify this compound as the resting state during catalytic C(sp2)-C(sp3) coupling. Variable time normalization analysis (VTNA) of in situ catalytic 19F NMR spectroscopic data was used to establish an experimental rate law that was first-order in a (FI)cobalt(II) precatalyst, zeroth-order in the alkyl halide, and first-order in an activated potassium methoxide-aryl boronate complex. These findings are consistent with turnover-limiting transmetalation that occurs prior to activation of the alkyl bromide electrophile. The involvement of boronate intermediates in transmetalation was corroborated by Hammett studies of electronically differentiated aryl boronic esters. Together, a cobalt(II)/cobalt(III) catalytic cycle was proposed that proceeds through a "boronate"-type mechanism.
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Affiliation(s)
- L Reginald Mills
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - David Gygi
- Chemical Process Development, Bristol Myers Squibb Company, New Brunswick, New Jersey 08903, United States
| | - Eric M Simmons
- Chemical Process Development, Bristol Myers Squibb Company, New Brunswick, New Jersey 08903, United States
| | - Steven R Wisniewski
- Chemical Process Development, Bristol Myers Squibb Company, New Brunswick, New Jersey 08903, United States
| | - Junho Kim
- 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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5
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Lv H, Xing F, Zhu S. Synthesis, structure, and properties of catechol functionalized tripodal chelate and its radical complex of strontium. INORG CHEM COMMUN 2022. [DOI: 10.1016/j.inoche.2022.109280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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6
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Swartjes A, White PB, Bruekers JPJ, Elemans JAAW, Nolte RJM. Paramagnetic relaxation enhancement NMR as a tool to probe guest binding and exchange in metallohosts. Nat Commun 2022; 13:1846. [PMID: 35388004 PMCID: PMC8986849 DOI: 10.1038/s41467-022-29406-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 02/21/2022] [Indexed: 11/11/2022] Open
Abstract
Paramagnetic metallohost systems can bind guest molecules and find application as biomimetic catalysts. Due to the presence of the paramagnetic metal center, rigorous characterization of these systems by NMR spectroscopy can be very difficult. We report here that metallohost-guest systems can be studied by using the paramagnetic relaxation enhancement (PRE) effect. Manganese(III) porphyrin cage compounds are shown through their PRE to thread and bind viologen guests, including a polymeric one. The binding constants and dethreading activation parameters are lower than those of the metal-free porphyrin cage compounds, which is proposed to be a result of charge repulsion of the trivalent metal center and dicationic viologen guest. The threading rate of the manganese(III) porphyrin cage onto the polymer is more than 10 times faster than that of the non-metallated one, which is ascribed to initial binding of the cage to the polymer chain prior to threading, and to an entron effect. Paramagnetic metallohost systems are difficult to characterize. Here the authors report that the paramagnetic relaxation enhancement effect can be used to prove by nuclear magnetic resonance experiments that Mn(III) porphyrin cage compounds can bind and thread low molecular weight and polymeric guests.
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Affiliation(s)
- Anne Swartjes
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Paul B White
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
| | - Jeroen P J Bruekers
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Johannes A A W Elemans
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
| | - Roeland J M Nolte
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
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McConnell AJ. Metallosupramolecular cages: from design principles and characterisation techniques to applications. Chem Soc Rev 2022; 51:2957-2971. [PMID: 35356956 DOI: 10.1039/d1cs01143j] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Although metallosupramolecular cages are self-assembled from seemingly simple building blocks, metal ions and organic ligands, architectures of increasingly large size and complexity are accessible and exploited in applications from catalysis to the stabilisation of reactive species. This Tutorial Review gives an introduction to the principles for designing metallosupramolecular cages and highlights advances in the design of large and lower symmetry cages. The characterisation and identification of cages relies on a number of complementary techniques with NMR spectroscopy, mass spectrometry, X-ray crystallography and computational methods being the focus of this review. Finally, examples of cages are discussed where these design principles and characterisation techniques are put into practice for an application or function of the cage.
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Affiliation(s)
- Anna J McConnell
- Otto Diels Institute of Organic Chemistry, Christian-Albrechts-Universität zu Kiel, Kiel 24098, Germany.
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Lüert D, Kreyenschmidt AK, Legendre CM, Herbst-Irmer R, Stalke D. A Sodium Sodate as Precursor for Lanthanide Bis(4- R-benzoxazol-2-yl)methanide Single-Molecule Magnets. Inorg Chem 2022; 61:5234-5244. [PMID: 35316598 DOI: 10.1021/acs.inorgchem.1c03714] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
From the sodium sodate precursor [(Na(thf)6][Na{(4-Me-NCOC6H3)2CH}2] (1) three isostructural dinuclear lanthanide complexes [(μ-Cl)LnIII{(4-MeNCOC6H3)2CH}2]2 with Ln = Gd (2), Dy (3), and Er (4) based on the N,N'-chelating monoanionic bis(4-methylbenzoxazol-2-yl)methanide ligand (titled "Mebox") were synthesized and characterized by X-ray diffraction and magnetic measurements. The sodium precursor 1 was analyzed via X-ray diffraction and diffusion-ordered NMR spectroscopy experiments (DOSY-NMR) in order to investigate its aggregation in solution and the solid state. The sodium analog [(thf)3Na(NCOC6H4)2CH] (1') based on the bis(benzoxazol-2-yl)-methanide ligand (titled "box") was prepared and analyzed for comparison reasons. From the lanthanide derivatives 2-4, the DyIII complex 3 displays slow relaxation of magnetization at zero field, with a relaxation barrier of U = 315.7 cm-1. The coupling strength between the two lanthanide centers was estimated with the GdIII equivalent 2, giving a weak antiferromagnetic coupling of J = -0.035 cm-1.
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Affiliation(s)
- Daniel Lüert
- Department of Inorganic Chemistry, University of Goettingen, Tammannstrasse 4, 37077 Goettingen, Germany
| | - Anne-Kathrin Kreyenschmidt
- Department of Inorganic Chemistry, University of Goettingen, Tammannstrasse 4, 37077 Goettingen, Germany
| | - Christina M Legendre
- Department of Inorganic Chemistry, University of Goettingen, Tammannstrasse 4, 37077 Goettingen, Germany
| | - Regine Herbst-Irmer
- Department of Inorganic Chemistry, University of Goettingen, Tammannstrasse 4, 37077 Goettingen, Germany
| | - Dietmar Stalke
- Department of Inorganic Chemistry, University of Goettingen, Tammannstrasse 4, 37077 Goettingen, Germany
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Takebayashi S, Fayzullin RR, Bansal R. Direct observation of reversible bond homolysis by 2D EXSY NMR. Chem Sci 2022; 13:9202-9209. [PMID: 36093009 PMCID: PMC9383717 DOI: 10.1039/d2sc03028d] [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: 05/31/2022] [Accepted: 07/07/2022] [Indexed: 11/21/2022] Open
Abstract
Bond homolysis is one of the most fundamental bond cleavage mechanisms. Thus, understanding of bond homolysis influences the development of a wide range of chemistry. Photolytic bond homolysis and its reverse process have been observed directly using time-resolved spectroscopy. However, direct observation of reversible bond homolysis remains elusive. Here, we report the direct observation of reversible Co–Co bond homolysis using two-dimensional nuclear magnetic resonance exchange spectroscopy (2D EXSY NMR). The characterization of species involved in this homolysis is firmly supported by diffusion ordered NMR spectroscopy (DOSY NMR). The unambiguous characterization of the Co–Co bond homolysis process enabled us to study ligand steric and electronic factors that influence the strength of the Co–Co bond. Understanding of these factors will contribute to rational design of multimetallic complexes with desired physical properties or catalytic activity. We report the first direct observation of reversible bond homolysis using EXSY NMR. This study revealed that electron donating groups weaken the Co–Co bond.![]()
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Affiliation(s)
- Satoshi Takebayashi
- Science and Technology Group Okinawa Institute of Science and Technology Graduate University 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
| | - Robert R. Fayzullin
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, 8 Arbuzov Street, Kazan 420088, Russian Federation
| | - Richa Bansal
- Science and Technology Group Okinawa Institute of Science and Technology Graduate University 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
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Singh S, Brooker S. Correlations between ligand field Δ o, spin crossover T 1/2 and redox potential E pa in a family of five dinuclear helicates. Chem Sci 2021; 12:10919-10929. [PMID: 34447566 PMCID: PMC8372313 DOI: 10.1039/d1sc01458g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/26/2021] [Indexed: 11/21/2022] Open
Abstract
A family of five new bis-bidentate azole-triazole Rat ligands (1,3-bis(5-(azole)-4-isobutyl-4H-1,2,4-triazol-3-yl)benzene), varying in choice of azole (2-imidazole, 4-imidazole, 1-methyl-4-imidazole, 4-oxazole and 4-thiazole), and the corresponding family of spin-crossover (SCO) and redox active triply bridged dinuclear helicates, [FeII 2L3]4+, has been prepared and characterised. X-ray crystal structures show all five Fe(ii) helicates are low spin at 100 K. Importantly, DOSY NMR confirms the intactness of these SCO-active dinuclear helicates in D3-MeCN solution, regardless of HS fraction: γ HS(298 K) = 0-0.81. Variable temperature 1H NMR Evans and UV-vis studies reveal that the helicates are SCO-active in MeCN solution. Indeed, the choice of azole in the Rat ligand used in [Fe2L3]4+ tunes: (a) solution SCO T 1/2 from 247 to 471 K, and (b) reversible redox potential, E m(FeII/III), from 0.25 to 0.67 V for four helicates, whilst one has an irreversible redox process, E pa = 0.78 V, vs. 0.01 M AgNO3/Ag. For the four reversible redox systems, a strong correlation (R 2 = 0.99) is observed between T 1/2 and E pa. Finally, the analogous Ni(ii) helicates have been prepared to obtain Δ o, establishing: (a) the ligand field strength order of the ligands: 4-imidazole (11 420) ∼ 1-methyl-4-imidazole (11 430) < 2-imidazole (11 505) ∼ 4-oxazole (11 516) < 4-thiazole (11 804 cm-1), (b) that Δ o ([NiII 2L3]4+) strongly correlates (R 2 = 0.87) with T 1/2 ([FeII 2L3]4+), and (c) interestingly that Δ o strongly correlates (R 2 = 0.98) with E pa for the four helicates with reversible redox, so the stronger the ligand field strength, the harder it is to oxidise the Fe(ii) to Fe(iii).
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Affiliation(s)
- Sandhya Singh
- Department of Chemistry, The MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago PO Box 56 Dunedin 9054 New Zealand
| | - Sally Brooker
- Department of Chemistry, The MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago PO Box 56 Dunedin 9054 New Zealand
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11
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Clauss R, Kazimir A, Straube A, Hey-Hawkins E. Palladium Goes First: A Neutral Asymmetric Heteroditopic N, P Ligand Forming Pd-3d Heterobimetallic Complexes. Inorg Chem 2021; 60:8722-8733. [PMID: 34060826 DOI: 10.1021/acs.inorgchem.1c00694] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
A facile two-step synthesis of bis(1-methylhydrazinyl)pyrimidine from pyridine-2-carbaldehyde and 2-diphenylphosphanylbenzaldehyde gave access to the new asymmetric ligand 1. The phosphane selectively guides PdII into the softer tridentate N,N,P pocket, yielding monometallic complex 2. A second reaction with a 3d transition metal complex precursor (groups 7 to 12) fills the vacant N,N,N pocket and thus provides a variety of heterobimetallic complexes of the type PdII/MII (M = Mn (3), Fe (4), Co (5), Ni (6), Cu (7), Zn (8)). Single-crystal X-ray diffraction studies were performed for all complexes. The assembly of μ2-chlorido-bridged dimers was observed for complexes 5-7 in the solid state, while DOSY NMR experiments have shown that 5-7 are unbridged monomers in solution. As an exception, FeII prefers to form the homoleptic meridional complex [Fe{PdCl(1)}2](OTf)4 (4). The electrochemical behavior and the effective magnetic moment in solution were investigated for all complexes by cyclic voltammetry and Evans method, respectively. Experimental UV/vis results were interpreted by performing TD-DFT calculations on 1, 2, and 3.
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Affiliation(s)
- Reike Clauss
- Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, D-04103 Leipzig, Germany
| | - Aleksandr Kazimir
- Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, D-04103 Leipzig, Germany
| | - Axel Straube
- Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, D-04103 Leipzig, Germany
| | - Evamarie Hey-Hawkins
- Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, D-04103 Leipzig, Germany
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12
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Yang X, DeLaney CR, Burns KT, Elrod LC, Mo W, Naumann H, Bhuvanesh N, Hall MB, Darensbourg MY. Self-Assembled Nickel-4 Supramolecular Squares and Assays for HER Electrocatalysts Derived Therefrom. Inorg Chem 2021; 60:7051-7061. [PMID: 33891813 DOI: 10.1021/acs.inorgchem.0c03613] [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
Solid-state structures find a self-assembled tetrameric nickel cage with carboxylate linkages, [Ni(N2S'O)I(CH3CN)]4 ([Ni-I]40), resulting from sulfur acetylation by sodium iodoacetate of an [NiN2S]22+ dimer in acetonitrile. Various synthetic routes to the tetramer, best described from XRD as a molecular square, were discovered to generate the hexacoordinate nickel units ligated by N2Sthioether, iodide, and two carboxylate oxygens, one of which is the bridge from the adjacent nickel unit in [Ni-I]40. Removal of the four iodides by silver ion precipitation yields an analogous species but with an additional vacant coordination site, [Ni-Solv]+, a cation but with coordinated solvent molecules. This also recrystallizes as the tetramer [Ni-Solv]44+. In solution, dissociation into the (presumed) monomer occurs, with coordinating solvents occupying the vacant site [Ni(N2S'O)I(solv)]0, ([Ni-I]0). Hydrodynamic radii determined from 1H DOSY NMR data suggest that monomeric units are present as well in CD2Cl2. Evans method magnetism values are consistent with triplet spin states in polar solvents; however, in CD2Cl2 solutions no paramagnetism is evident. The abilities of [Ni-I]40 and [Ni-Solv]44+ to serve as sources of electrocatalysts, or precatalysts, for the hydrogen evolution reaction (HER) were explored. Cyclic voltammetry responses and bulk coulometry with gas chromatographic analysis demonstrated that a stronger acid, trifluoroacetic acid, as a proton source resulted in H2 production from both electroprecatalysts; however, electrocatalysis developed primarily from uncharacterized deposits on the electrode. With acetic acid as a proton source, the major contribution to the HER is from homogeneous electrocatalysis. Overpotentials of 490 mV were obtained for both the solution-phase [Ni-I]0 and [Ni-Solv]+. While the electrocatalyst derived from [Ni-Solv]+ has a substantially higher TOF (102 s-1) than [Ni-I]0 (19 s-1), it has a shorter catalytically active lifespan (4 h) in comparison to [Ni-I]0 (>18 h).
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Affiliation(s)
- Xuemei Yang
- Texas A&M University, Department of Chemistry, College Station, Texas 77843, United States
| | - Christopher R DeLaney
- Texas A&M University, Department of Chemistry, College Station, Texas 77843, United States
| | - Kyle T Burns
- Texas A&M University, Department of Chemistry, College Station, Texas 77843, United States
| | - Lindy C Elrod
- Texas A&M University, Department of Chemistry, College Station, Texas 77843, United States
| | - Wenting Mo
- Texas A&M University, Department of Chemistry, College Station, Texas 77843, United States
| | - Haley Naumann
- Texas A&M University, Department of Chemistry, College Station, Texas 77843, United States
| | - Nattamai Bhuvanesh
- Texas A&M University, Department of Chemistry, College Station, Texas 77843, United States
| | - Michael B Hall
- Texas A&M University, Department of Chemistry, College Station, Texas 77843, United States
| | - Marcetta Y Darensbourg
- Texas A&M University, Department of Chemistry, College Station, Texas 77843, United States
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13
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Deng S, Diaconescu PL. A switchable dimeric yttrium complex and its three catalytic states in ring opening polymerization. Inorg Chem Front 2021. [DOI: 10.1039/d0qi01479f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A dimeric yttrium phenoxide complex can be oxidized in a stepwise fashion to access three oxidation states. The three states show different activity in the ring opening polymerization of cyclic esters and epoxides.
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Affiliation(s)
- Shijie Deng
- University of California
- Los Angeles
- Department of Chemistry and Biochemistry
- Los Angeles
- USA
| | - Paula L. Diaconescu
- University of California
- Los Angeles
- Department of Chemistry and Biochemistry
- Los Angeles
- USA
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14
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Lehr M, Paschelke T, Trumpf E, Vogt A, Näther C, Sönnichsen FD, McConnell AJ. A Paramagnetic NMR Spectroscopy Toolbox for the Characterisation of Paramagnetic/Spin-Crossover Coordination Complexes and Metal-Organic Cages. Angew Chem Int Ed Engl 2020; 59:19344-19351. [PMID: 33448544 PMCID: PMC7590057 DOI: 10.1002/anie.202008439] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Indexed: 12/14/2022]
Abstract
The large paramagnetic shifts and short relaxation times resulting from the presence of a paramagnetic centre complicate NMR data acquisition and interpretation in solution. As a result, NMR analysis of paramagnetic complexes is limited in comparison to diamagnetic compounds and often relies on theoretical models. We report a toolbox of 1D (1H, proton-coupled 13C, selective 1H-decoupling 13C, steady-state NOE) and 2D (COSY, NOESY, HMQC) paramagnetic NMR methods that enables unprecedented structural characterisation and in some cases, provides more structural information than would be observable for a diamagnetic analogue. We demonstrate the toolbox's broad versatility for fields from coordination chemistry and spin-crossover complexes to supramolecular chemistry through the characterisation of CoII and high-spin FeII mononuclear complexes as well as a Co4L6 cage.
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Affiliation(s)
- Marc Lehr
- Otto Diels Institute of Organic ChemistryChristian-Albrechts-Universität zu KielOtto-Hahn-Platz 4Kiel24098Germany
| | - Tobias Paschelke
- Otto Diels Institute of Organic ChemistryChristian-Albrechts-Universität zu KielOtto-Hahn-Platz 4Kiel24098Germany
| | - Eicke Trumpf
- Otto Diels Institute of Organic ChemistryChristian-Albrechts-Universität zu KielOtto-Hahn-Platz 4Kiel24098Germany
| | - Anna‐Marlene Vogt
- Otto Diels Institute of Organic ChemistryChristian-Albrechts-Universität zu KielOtto-Hahn-Platz 4Kiel24098Germany
| | - Christian Näther
- Institute of Inorganic ChemistryChristian-Albrechts-Universität zu KielMax-Eyth-Straße 2Kiel24118Germany
| | - Frank D. Sönnichsen
- Otto Diels Institute of Organic ChemistryChristian-Albrechts-Universität zu KielOtto-Hahn-Platz 4Kiel24098Germany
| | - Anna J. McConnell
- Otto Diels Institute of Organic ChemistryChristian-Albrechts-Universität zu KielOtto-Hahn-Platz 4Kiel24098Germany
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15
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Lehr M, Paschelke T, Trumpf E, Vogt A, Näther C, Sönnichsen FD, McConnell AJ. Ein Methodenrepertoire für die paramagnetische NMR‐Spektroskopie zur Charakterisierung von paramagnetischen/Spin‐Crossover‐ Komplexen und Metall‐organischen Käfigverbindungen. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008439] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Marc Lehr
- Otto-Diels-Institut für Organische Chemie Christian-Albrechts-Universität zu Kiel Otto-Hahn-Platz 4 Kiel 24098 Deutschland
| | - Tobias Paschelke
- Otto-Diels-Institut für Organische Chemie Christian-Albrechts-Universität zu Kiel Otto-Hahn-Platz 4 Kiel 24098 Deutschland
| | - Eicke Trumpf
- Otto-Diels-Institut für Organische Chemie Christian-Albrechts-Universität zu Kiel Otto-Hahn-Platz 4 Kiel 24098 Deutschland
| | - Anna‐Marlene Vogt
- Otto-Diels-Institut für Organische Chemie Christian-Albrechts-Universität zu Kiel Otto-Hahn-Platz 4 Kiel 24098 Deutschland
| | - Christian Näther
- Institut für Anorganische Chemie Christian-Albrechts-Universität zu Kiel Max-Eyth-Straße 2 Kiel 24118 Deutschland
| | - Frank D. Sönnichsen
- Otto-Diels-Institut für Organische Chemie Christian-Albrechts-Universität zu Kiel Otto-Hahn-Platz 4 Kiel 24098 Deutschland
| | - Anna J. McConnell
- Otto-Diels-Institut für Organische Chemie Christian-Albrechts-Universität zu Kiel Otto-Hahn-Platz 4 Kiel 24098 Deutschland
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16
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Bullock RM, Chen JG, Gagliardi L, Chirik PJ, Farha OK, Hendon CH, Jones CW, Keith JA, Klosin J, Minteer SD, Morris RH, Radosevich AT, Rauchfuss TB, Strotman NA, Vojvodic A, Ward TR, Yang JY, Surendranath Y. Using nature's blueprint to expand catalysis with Earth-abundant metals. Science 2020; 369:eabc3183. [PMID: 32792370 PMCID: PMC7875315 DOI: 10.1126/science.abc3183] [Citation(s) in RCA: 188] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Numerous redox transformations that are essential to life are catalyzed by metalloenzymes that feature Earth-abundant metals. In contrast, platinum-group metals have been the cornerstone of many industrial catalytic reactions for decades, providing high activity, thermal stability, and tolerance to chemical poisons. We assert that nature's blueprint provides the fundamental principles for vastly expanding the use of abundant metals in catalysis. We highlight the key physical properties of abundant metals that distinguish them from precious metals, and we look to nature to understand how the inherent attributes of abundant metals can be embraced to produce highly efficient catalysts for reactions crucial to the sustainable production and transformation of fuels and chemicals.
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Affiliation(s)
- R Morris Bullock
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
| | - Jingguang G Chen
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA.
- Chemistry Division, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Laura Gagliardi
- Department of Chemistry, Minnesota Supercomputing Institute, and Chemical Theory Center, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Paul J Chirik
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Omar K Farha
- Department of Chemistry and Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Christopher H Hendon
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR 97403, USA
| | - Christopher W Jones
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - John A Keith
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Jerzy Klosin
- Core R&D, Dow Chemical Co., Midland, MI 48674, USA
| | - Shelley D Minteer
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Robert H Morris
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Alexander T Radosevich
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Thomas B Rauchfuss
- School of Chemical Sciences, University of Illinois, Urbana, IL 61801, USA
| | - Neil A Strotman
- Process Research and Development, Merck & Co. Inc., Rahway, NJ 07065, USA
| | - Aleksandra Vojvodic
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Thomas R Ward
- Department of Chemistry, University of Basel, CH-4058 Basel, Switzerland
| | - Jenny Y Yang
- Department of Chemistry, University of California, Irvine, CA 92697, USA
| | - Yogesh Surendranath
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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17
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Maskeri MA, Brueckner AC, Feoktistova T, O'Connor MJ, Walden DM, Cheong PHY, Scheidt KA. Mechanism and origins of selectivity in the enantioselective oxa-Pictet-Spengler reaction: a cooperative catalytic complex from a hydrogen bond donor and chiral phosphoric acid. Chem Sci 2020; 11:8736-8743. [PMID: 34123127 PMCID: PMC8163393 DOI: 10.1039/d0sc03250f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 07/21/2020] [Indexed: 11/29/2022] Open
Abstract
Enantioselective additions to oxocarbenium ions are high-value synthetic transformations but have proven challenging to achieve. In particular, the oxa-Pictet-Spengler reaction has only recently been rendered enantioselective. We report experimental and computational studies on the mechanism of this unusual transformation. Herein we reveal that this reaction is hypothesized to proceed through a self-assembled ternary hydrogen bonding complex involving the substrate, chiral phosphate ion, and a urea hydrogen-bond donor. The computed transition state reveals C2-symmetric grooves in the chiral phosphate that are occupied by the urea and substrate. Occupation of one of these grooves by the urea co-catalyst tunes the available reactive volume and enhances the stereoselectivity of the chiral phosphate catalyst.
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Affiliation(s)
- Mark A Maskeri
- Department of Chemistry, Center for Molecular Innovation and Drug Discovery, Northwestern University Evanston IL 60208 USA
| | | | | | - Matthew J O'Connor
- Department of Chemistry, Center for Molecular Innovation and Drug Discovery, Northwestern University Evanston IL 60208 USA
| | - Daniel M Walden
- Department of Chemistry, Oregon State University Corvallis OR 97331 USA
| | | | - Karl A Scheidt
- Department of Chemistry, Center for Molecular Innovation and Drug Discovery, Northwestern University Evanston IL 60208 USA
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18
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Crockett MP, Wong AS, Li B, Byers JA. Rational Design of an Iron‐Based Catalyst for Suzuki–Miyaura Cross‐Couplings Involving Heteroaromatic Boronic Esters and Tertiary Alkyl Electrophiles. Angew Chem Int Ed Engl 2020; 59:5392-5397. [DOI: 10.1002/anie.201914315] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Michael P. Crockett
- Department of ChemistryBoston College Merkert Chemistry Center, 2609 Beacon St. Chestnut Hill MA 02467 USA
| | - Alexander S. Wong
- Department of ChemistryBoston College Merkert Chemistry Center, 2609 Beacon St. Chestnut Hill MA 02467 USA
| | - Bo Li
- Department of ChemistryBoston College Merkert Chemistry Center, 2609 Beacon St. Chestnut Hill MA 02467 USA
| | - Jeffery A. Byers
- Department of ChemistryBoston College Merkert Chemistry Center, 2609 Beacon St. Chestnut Hill MA 02467 USA
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19
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Crockett MP, Wong AS, Li B, Byers JA. Rational Design of an Iron‐Based Catalyst for Suzuki–Miyaura Cross‐Couplings Involving Heteroaromatic Boronic Esters and Tertiary Alkyl Electrophiles. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201914315] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Michael P. Crockett
- Department of ChemistryBoston College Merkert Chemistry Center, 2609 Beacon St. Chestnut Hill MA 02467 USA
| | - Alexander S. Wong
- Department of ChemistryBoston College Merkert Chemistry Center, 2609 Beacon St. Chestnut Hill MA 02467 USA
| | - Bo Li
- Department of ChemistryBoston College Merkert Chemistry Center, 2609 Beacon St. Chestnut Hill MA 02467 USA
| | - Jeffery A. Byers
- Department of ChemistryBoston College Merkert Chemistry Center, 2609 Beacon St. Chestnut Hill MA 02467 USA
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