1
|
Wilson CV, Holland PL. Mechanism of Alkene Hydrofunctionalization by Oxidative Cobalt(salen) Catalyzed Hydrogen Atom Transfer. J Am Chem Soc 2024; 146:2685-2700. [PMID: 38227206 PMCID: PMC10872242 DOI: 10.1021/jacs.3c12329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
Oxidative MHAT hydrofunctionalization of alkenes provides a mild cobalt-catalyzed route to forming C-N and C-O bonds. Here, we characterize relevant salen-supported cobalt complexes and their reactions with alkenes, silanes, oxidant, and solvent. These stoichiometric investigations are complemented by kinetic studies of the catalytic reaction and catalyst speciation. We describe the solution characterization of an elusive cobalt(III) fluoride complex, which surprisingly is not the species that reacts with silane under catalytic conditions; rather, a cobalt(III) aquo complex is more active. Accordingly, the addition of water (0.15 M) speeds the catalytic reaction, and kinetic studies show that water addition enables catalytic product formation in 2 h at -50 °C in acetone. Under these conditions, cobalt(III) resting states can be observed by UV-vis spectrophotometry, including a cobalt(III)-alkyl complex. It comes from a transient cobalt(III) hydride complex that is formed in the turnover-limiting step of the catalytic cycle. This hydride readily degrades but not to H2; it releases H+ through a bimetallic pathway that explains the [Co]2 dependence of the off-cycle reaction. In contrast, the rate of the catalytic reaction follows the power law kobs[Co]1[silane]1. Because of the different [Co] dependence of the catalytic reaction and the degradation reaction, lower catalyst loading improves the yield of the catalytic reaction by reducing the relative rate of unproductive silane/oxidant consumption. These studies illuminate mechanistic details of oxidative MHAT hydrofunctionalization of alkenes and lay the groundwork for understanding other catalytic reactions mediated by cobalt hydride and cobalt alkyl complexes.
Collapse
Affiliation(s)
- Conner V. Wilson
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, CT 06520, USA
| | - Patrick L. Holland
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, CT 06520, USA
| |
Collapse
|
2
|
Gupta A, Rahaman A, Bhadra S. Bioinspired Functionalization of Carbonyl Compounds Enabled by Metal Chelated Bifunctional Ligands. Chemistry 2024; 30:e202302812. [PMID: 37807759 DOI: 10.1002/chem.202302812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 09/29/2023] [Accepted: 10/04/2023] [Indexed: 10/10/2023]
Abstract
In Nature, enzymatic reactions proceed through exceptionally ordered transition states giving rise to extraordinary levels of stereoselection. In those reactions, the active site of the enzyme plays crucial roles - through one position, it holds the substrate in the proximity to the reaction epicentre that facilitates both the reactivity and stereoselectivity of the chemical process. Inspired by this natural phenomenon, synthetic chemists have designed bifunctional ligands that not only coordinate to a metal centre but also preassociate with an organic substrate, for example aldehyde and ketone, and exerts stereodirecting influence to accelerate the attack of the incoming reacting partner from a particular enantiotopic face. The chief goal of the current review is to give an overview of the recently developed approaches enabled by privileged bio-inspired bifunctional ligands that not only bind to the metal catalyst but also activates carbonyl substrates via organocatalysis, thereby easing in the new bond forming step. As carbonyl α-functionalizations are dominated by enamine and enolate chemistry, the current review primarily focusses on enamine- and enolate-metal catalysis by bifunctional ligands. Thus, developments based on traditional cooperative catalysis occurring through two directly coupled but independent catalytic cycles of an organocatalyst and a metal catalyst are not covered.
Collapse
Affiliation(s)
- Aniket Gupta
- Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemicals Research Institute, GB Marg, 364002, Bhavnagar, India
- Academy of Scientific and Innovative Research (AcSIR), 201002, Ghaziabad, India
- Current address: School of Chemistry, The University of Birmingham, B15 2TT, Birmingham, UK
| | - Ajijur Rahaman
- Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemicals Research Institute, GB Marg, 364002, Bhavnagar, India
- Academy of Scientific and Innovative Research (AcSIR), 201002, Ghaziabad, India
| | - Sukalyan Bhadra
- Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemicals Research Institute, GB Marg, 364002, Bhavnagar, India
- Academy of Scientific and Innovative Research (AcSIR), 201002, Ghaziabad, India
| |
Collapse
|
3
|
Sandvoß A, Maag H, Daniliuc CG, Schollmeyer D, Wahl JM. Dynamic kinetic resolution of transient hemiketals: a strategy for the desymmetrisation of prochiral oxetanols. Chem Sci 2022; 13:6297-6302. [PMID: 35733901 PMCID: PMC9159106 DOI: 10.1039/d2sc01547a] [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: 03/16/2022] [Accepted: 05/03/2022] [Indexed: 11/21/2022] Open
Abstract
Identification of an electron poor trifluoroacetophenone allows the formation of uniquely stable hemiketals from prochiral oxetanols. When exposed to a cobalt(ii) catalyst, efficient ring-opening to densely functionalized dioxolanes is observed. Mechanistic studies suggest an unprecedented redox process between the cobalt(ii) catalyst and the hemiketal that initiates the oxetane-opening. Based on this observation, a dynamic kinetic resolution of the transient hemiketals is explored that uses a Katsuki-type ligand for stereoinduction (up to 99 : 1 dr and 96 : 4 er) and allows a variety of 1,3-dioxolanes to be accessed (20 examples up to 98% yield). Desymmetrization of prochiral oxetanols via an electron-deficient hemiketal intermediate is achieved. Key to this process is the catalyst's chiral recognition of one of the two hemiketal enantiomers enabling an efficient dynamic kinetic resolution.![]()
Collapse
Affiliation(s)
- Alexander Sandvoß
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Corrensstraße 36 48149 Münster Germany.,Department Chemie, Johannes Gutenberg-Universität Duesbergweg 10-14 55128 Mainz Germany
| | - Henning Maag
- Department Chemie, Johannes Gutenberg-Universität Duesbergweg 10-14 55128 Mainz Germany
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Corrensstraße 36 48149 Münster Germany
| | - Dieter Schollmeyer
- Department Chemie, Johannes Gutenberg-Universität Duesbergweg 10-14 55128 Mainz Germany
| | - Johannes M Wahl
- Department Chemie, Johannes Gutenberg-Universität Duesbergweg 10-14 55128 Mainz Germany
| |
Collapse
|
4
|
Fischer D, Balkenhohl M, Carreira EM. Cobalt-Catalyzed Cyclization of Unsaturated N-Acyl Sulfonamides: a Diverted Mukaiyama Hydration Reaction. JACS AU 2022; 2:1071-1077. [PMID: 35647594 PMCID: PMC9131372 DOI: 10.1021/jacsau.2c00186] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/26/2022] [Accepted: 04/28/2022] [Indexed: 06/15/2023]
Abstract
The cycloisomerization of β-, γ-, and δ-unsaturated N-acyl sulfonamides to N-sulfonyl lactams and imidates is reported. This transformation is effected in the presence of a CoIII(salen) catalyst using t-BuOOH or air as the oxidant. The method shows good functional group tolerance (alkyl, aryl, heteroaryl, ether, N-Boc) and furnishes an underexplored class of cyclic building blocks. The strong solvent dependence of the transformation is investigated, and the synthetic versatility of the N-sulfonyl imidate product class is highlighted.
Collapse
|
5
|
Yang HQ, Chen ZX. Exploring the mechanism and counterion activity regulation in the Co III(salen)-catalyzed hydration of propylene oxide. Phys Chem Chem Phys 2020; 22:22417-22425. [PMID: 32996507 DOI: 10.1039/d0cp03996a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
CoIII(salen)-X (X = Cl-, OAc-, and OTs-) mediated hydration of propylene oxide (PO) to propylene glycol has been investigated in detail using density functional theory (DFT) calculations. Two kinds of reaction mechanisms, the concerted and stepwise pathways, were scrutinized. For the eight concerted routes, the cooperative bimetallic route in which the middle carbon atom is attacked by the nucleophilic oxygen atom (route VI-m) was calculated to be the most favorable, and among the three catalysts examined H2O-CoIII-OTs was found to be the most active, due to the strong hydrogen bonding between the nucleophilic H2O and the ring oxygen atom in the epoxides as well as the extra π-π stacking interaction. For the stepwise mechanism which consists of the formation of H2O-CoIII-OH, the ring-opening of PO and propylene glycol formation, our studies reveal that different H2O-CoIII-Xs behave kinetically very similarly in the course of propylene glycol formation, but show a notable difference in the rate of H2O-CoIII-OH formation with Cl- > OAc- > OTs-. The rate ordering with which we rationalize the experimental phenomena well is disclosed to be consistent with the nucleophilicity of the counterions by molecular electrostatic potential, condensed Fukui function and condensed local softness. We show that the nucleophilicity of the counterion determines the favorable mechanism that PO hydration follows.
Collapse
Affiliation(s)
- Hui-Qing Yang
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China.
| | | |
Collapse
|
6
|
NNN‐
Cobalt(II) Pincer Complexes: Paramagnetic NMR Spectroscopy in Solution and Application as Hydrosilylation Catalysts. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000378] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
|
7
|
Jin C, Chen L, Yang H, Chen Z. A Computational Study of Solvent and Electric Field Effects on Propylene Oxide Ring‐Opening Reaction. ChemistrySelect 2020. [DOI: 10.1002/slct.201903710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Cheng‐Yu Jin
- Institute of Theoretical and Computational ChemistryKey Laboratory of Mesoscopic Chemistry of MOESchool of Chemistry and Chemical EngineeringNanjing University Nanjing 210093 China
| | - Lei Chen
- Institute of Theoretical and Computational ChemistryKey Laboratory of Mesoscopic Chemistry of MOESchool of Chemistry and Chemical EngineeringNanjing University Nanjing 210093 China
| | - Hui‐Qing Yang
- Institute of Theoretical and Computational ChemistryKey Laboratory of Mesoscopic Chemistry of MOESchool of Chemistry and Chemical EngineeringNanjing University Nanjing 210093 China
| | - Zhao‐Xu Chen
- Institute of Theoretical and Computational ChemistryKey Laboratory of Mesoscopic Chemistry of MOESchool of Chemistry and Chemical EngineeringNanjing University Nanjing 210093 China
| |
Collapse
|
8
|
Abstract
Chiral salen-metal complexes are among the most versatile asymmetric catalysts and have found utility in fields ranging from materials chemistry to organic synthesis. These complexes are capable of inducing chirality in products formed from a wide variety of chemical processes, often with close to perfect stereoinduction. Salen ligands are tunable for steric as well as electronic properties, and their ability to coordinate a large number of metals gives the derived chiral salen-metal complex very broad utility in asymmetric catalysis. This review primarily summarizes developments in chiral salen-metal catalysis over the last two decades with particular emphasis on those applications of importance in asymmetric synthesis.
Collapse
Affiliation(s)
- Subrata Shaw
- Center for the Development of Therapeutics , Broad Institute of MIT and Harvard , 415 Main Street , Cambridge , Massachusetts 02142 , United States
| | - James D White
- Department of Chemistry , Oregon State University , Corvallis , Oregon 97331 , United States
| |
Collapse
|
9
|
Abstract
A catalytic ring-opening reaction of epoxides by nucleophilic trifluoromethoxylation of trifluoromethyl arylsulfonate has been developed based on the use of a cobalt catalyst. This reaction provides an efficient, simple route for directly construction of a wide range of vicinal trifluoromethoxyhydrins under mild conditions. In addition, this method can convert terminal epoxides into target products with good chemo- and regioselectivity.
Collapse
Affiliation(s)
- Jie Liu
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry , Nankai University , Tianjin 300071 , China
| | - Yongliang Wei
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry , Nankai University , Tianjin 300071 , China
| | - Pingping Tang
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry , Nankai University , Tianjin 300071 , China.,Collaborative Innovation Center of Chemical Science and Engineering , Tianjin 300071 , China
| |
Collapse
|
10
|
Bandara GC, Heist CA, Remcho VT. Chromatographic Separation and Visual Detection on Wicking Microfluidic Devices: Quantitation of Cu 2+ in Surface, Ground, and Drinking Water. Anal Chem 2018; 90:2594-2600. [PMID: 29333859 DOI: 10.1021/acs.analchem.7b04087] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Copper is widely applied in industrial and technological applications and is an essential micronutrient for humans and animals. However, exposure to high environmental levels of copper, especially through drinking water, can lead to copper toxicity, resulting in severe acute and chronic health effects. Therefore, regular monitoring of aqueous copper ions has become necessary as recent anthropogenic activities have led to elevated environmental concentrations of copper. On-site monitoring processes require an inexpensive, simple, and portable analytical approach capable of generating reliable qualitative and quantitative data efficiently. Membrane-based lateral flow microfluidic devices are ideal candidates as they facilitate rapid, inexpensive, and portable measurements. Here we present a simple, chromatographic separation approach in combination with a visual detection method for Cu2+ quantitation, performed in a lateral flow microfluidic channel. This method appreciably minimizes interferences by incorporating a nonspecific polymer inclusion membrane (PIM) based assay with a "dot-counting" approach to quantification. In this study, hydrophobic polycaprolactone (PCL)-filled glass microfiber (GMF) membranes were used as the base substrate onto which the PIM was evenly dispensed as an array of dots. The devices thus prepared were then selectively exposed to oxygen radicals through a mask to generate a hydrophilic surface path along which the sample was wicked. Using this approach, copper concentrations from 1 to 20 ppm were quantified from 5 μL samples using only visual observation of the assay device.
Collapse
Affiliation(s)
- Gayan C Bandara
- Department of Chemistry, Oregon State University , Corvallis, Oregon 97331, United States
| | - Christopher A Heist
- Department of Chemistry, Oregon State University , Corvallis, Oregon 97331, United States
| | - Vincent T Remcho
- Department of Chemistry, Oregon State University , Corvallis, Oregon 97331, United States
| |
Collapse
|
11
|
|
12
|
Kumar P, Tripathi D, Sharma BM, Dwivedi N. Transition metal catalysis—a unique road map in the stereoselective synthesis of 1,3-polyols. Org Biomol Chem 2017; 15:733-761. [DOI: 10.1039/c6ob01925k] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The present review summarizes recent diverse reactions employed in the formation of 1,3-polyols providing an overview of the mechanistic pathway and the enantioselectivity obtained, in terms of the properties of transition metals directly involved in the catalytic transformations and their interaction with various ligands.
Collapse
Affiliation(s)
- Pradeep Kumar
- Organic Chemistry Division
- CSIR-National Chemical Laboratory
- Pune 411008
- India
| | - Divya Tripathi
- Organic Chemistry Division
- CSIR-National Chemical Laboratory
- Pune 411008
- India
| | - Brijesh M. Sharma
- Organic Chemistry Division
- CSIR-National Chemical Laboratory
- Pune 411008
- India
| | - Namrata Dwivedi
- Organic Chemistry Division
- CSIR-National Chemical Laboratory
- Pune 411008
- India
| |
Collapse
|
13
|
Buchwald JR, Kal S, Civic MR, deJoode IM, Filatov AS, Dinolfo PH. Spin modulation and electrochemical behavior of a five-coordinate cobalt(III) salen complex. J COORD CHEM 2016. [DOI: 10.1080/00958972.2016.1175001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- James R. Buchwald
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Subhadeep Kal
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Marissa R. Civic
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Ian M. deJoode
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Alexander S. Filatov
- Department of Chemistry, University at Albany, State University of New York, Albany, NY, USA
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | - Peter H. Dinolfo
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, USA
| |
Collapse
|
14
|
Clarke RM, Hazin K, Thompson JR, Savard D, Prosser KE, Storr T. Electronic Structure Description of a Doubly Oxidized Bimetallic Cobalt Complex with Proradical Ligands. Inorg Chem 2015; 55:762-74. [DOI: 10.1021/acs.inorgchem.5b02231] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Ryan M. Clarke
- Department
of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Khatera Hazin
- Department
of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - John R. Thompson
- Department
of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Didier Savard
- Department
of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Kathleen E. Prosser
- Department
of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Tim Storr
- Department
of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| |
Collapse
|
15
|
Bhadra S, Akakura M, Yamamoto H. Design of a New Bimetallic Catalyst for Asymmetric Epoxidation and Sulfoxidation. J Am Chem Soc 2015; 137:15612-5. [DOI: 10.1021/jacs.5b11429] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sukalyan Bhadra
- Molecular
Catalyst Research Center, Chubu University, 1200, Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
| | - Matsujiro Akakura
- Department
of Chemistry, Aichi University of Education, Igaya-cho, Kariya, Aichi 448-8542, Japan
| | - Hisashi Yamamoto
- Molecular
Catalyst Research Center, Chubu University, 1200, Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
| |
Collapse
|
16
|
Offermans WK, Bizzarri C, Leitner W, Müller TE. Surprisingly facile CO2 insertion into cobalt alkoxide bonds: A theoretical investigation. Beilstein J Org Chem 2015; 11:1340-51. [PMID: 26425188 PMCID: PMC4578342 DOI: 10.3762/bjoc.11.144] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Accepted: 07/10/2015] [Indexed: 01/26/2023] Open
Abstract
Exploiting carbon dioxide as co-monomer with epoxides in the production of polycarbonates is economically highly attractive. More effective catalysts for this reaction are intensively being sought. To promote better understanding of the catalytic pathways, this study uses density functional theory calculations to elucidate the reaction step of CO2 insertion into cobalt(III)-alkoxide bonds, which is also the central step of metal catalysed carboxylation reactions. It was found that CO2 insertion into the cobalt(III)-alkoxide bond of [(2-hydroxyethoxy)Co(III)(salen)(L)] complexes (salen = N,N"-bis(salicyliden-1,6-diaminophenyl)) is exothermic, whereby the exothermicity depends on the trans-ligand L. The more electron-donating this ligand is, the more exothermic the insertion step is. Interestingly, we found that the activation barrier decreases with increasing exothermicity of the CO2 insertion. Hereby, a linear Brønsted-Evans-Polanyi relationship was found between the activation energy and the reaction energy.
Collapse
Affiliation(s)
- Willem K Offermans
- CAT Catalytic Center, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany
| | - Claudia Bizzarri
- CAT Catalytic Center, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany
| | - Walter Leitner
- Lehrstuhl für Technische Chemie und Petrolchemie, ITMC, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany
| | - Thomas E Müller
- CAT Catalytic Center, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany
| |
Collapse
|
17
|
Santiago-Rodríguez Y, Curet-Arana MC. Quantum mechanical study of the reaction of CO2 and ethylene oxide catalyzed by metal–salen complexes: effect of the metal center and the axial ligand. REACTION KINETICS MECHANISMS AND CATALYSIS 2015. [DOI: 10.1007/s11144-015-0904-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
18
|
Chiang L, Herasymchuk K, Thomas F, Storr T. Influence of Electron-Withdrawing Substituents on the Electronic Structure of Oxidized Ni and Cu Salen Complexes. Inorg Chem 2015; 54:5970-80. [DOI: 10.1021/acs.inorgchem.5b00783] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Linus Chiang
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Khrystyna Herasymchuk
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Fabrice Thomas
- Département de Chimie Moléculaire,
Chimie Inorganique Redox (CIRE), UMR-5250, Université Grenoble Alpes, BP 53, 38041 Grenoble
Cedex 9, France
| | - Tim Storr
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| |
Collapse
|
19
|
Co(III) complexes of tetradentate X3L type ligands: Synthesis, electronic structure, and reactivity. Inorganica Chim Acta 2015. [DOI: 10.1016/j.ica.2015.01.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
20
|
Kochem A, Gellon G, Jarjayes O, Philouze C, Leconte N, van Gastel M, Bill E, Thomas F. A singlet ground state for a cobalt(II)-anilinosalen radical complex. Chem Commun (Camb) 2015; 50:4924-6. [PMID: 24700242 DOI: 10.1039/c4cc00952e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The cobalt(II) anilinosalen complex [Co(II)(L)] was prepared and subsequently oxidized by one electron. The resulting cation comprises a square planar low spin Co(II) ion anti-ferromagnetically exchange coupled to an anilinyl radical.
Collapse
Affiliation(s)
- Amélie Kochem
- Département de Chimie Moléculaire - Chimie Inorganique Redox Biomimétique (CIRE) - UMR CNRS 5250, Université J. Fourier, B. P. 53, 38041 Grenoble cedex 9, France.
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Njiojob CN, Rhinehart JL, Bozell JJ, Long BK. Synthesis of Enantiomerically Pure Lignin Dimer Models for Catalytic Selectivity Studies. J Org Chem 2015; 80:1771-80. [DOI: 10.1021/jo502685k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Costyl N. Njiojob
- Department
of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
- Center
for Renewable
Carbon, University of Tennessee, Knoxville, Tennessee 37917, United States
| | - Jennifer L. Rhinehart
- Department
of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Joseph J. Bozell
- Center
for Renewable
Carbon, University of Tennessee, Knoxville, Tennessee 37917, United States
| | - Brian K. Long
- Department
of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| |
Collapse
|
22
|
Xi X, Shao J, Hu X, Wu Y. Structure and asymmetric epoxidation reactivity of chiral Mn(iii) salen catalysts modified by different axial anions. RSC Adv 2015. [DOI: 10.1039/c5ra13178b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The axial anions influence the electronic structure, steric configuration, and enantioselectivity of the chiral Mn(iii) salen complexes.
Collapse
Affiliation(s)
- Xiuxing Xi
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
| | - Jing Shao
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
| | - Xingbang Hu
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
| | - Youting Wu
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
| |
Collapse
|
23
|
Roy T, Barik S, Kumar M, Kureshy RI, Ganguly B, Khan NUH, Abdi SHR, Bajaj HC. Asymmetric hydrolytic kinetic resolution with recyclable polymeric Co(iii)–salen complexes: a practical strategy in the preparation of (S)-metoprolol, (S)-toliprolol and (S)-alprenolol: computational rationale for enantioselectivity. Catal Sci Technol 2014. [DOI: 10.1039/c4cy00594e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Role of chiral/achiral linker in asymmetric HKR of terminal epoxides using recyclable polymeric Co(iii) salen complexes.
Collapse
Affiliation(s)
- Tamal Roy
- Discipline of Inorganic Materials and Catalysis
- CSIR
- Central Salt and Marine Chemicals Research Institute (CSMCRI)
- Bhavnagar 364 021, India
| | - Sunirmal Barik
- Academy of Scientific and Innovative Research
- CSIR-CSMCRI
- Bhavnagar, India
- Analytical Discipline and Centralised Instrumental Facility
- CSIR
| | - Manish Kumar
- Discipline of Inorganic Materials and Catalysis
- CSIR
- Central Salt and Marine Chemicals Research Institute (CSMCRI)
- Bhavnagar 364 021, India
- Academy of Scientific and Innovative Research
| | - Rukhsana I. Kureshy
- Discipline of Inorganic Materials and Catalysis
- CSIR
- Central Salt and Marine Chemicals Research Institute (CSMCRI)
- Bhavnagar 364 021, India
- Academy of Scientific and Innovative Research
| | - Bishwajit Ganguly
- Academy of Scientific and Innovative Research
- CSIR-CSMCRI
- Bhavnagar, India
- Analytical Discipline and Centralised Instrumental Facility
- CSIR
| | - Noor-ul H. Khan
- Discipline of Inorganic Materials and Catalysis
- CSIR
- Central Salt and Marine Chemicals Research Institute (CSMCRI)
- Bhavnagar 364 021, India
- Academy of Scientific and Innovative Research
| | - Sayed H. R. Abdi
- Discipline of Inorganic Materials and Catalysis
- CSIR
- Central Salt and Marine Chemicals Research Institute (CSMCRI)
- Bhavnagar 364 021, India
- Academy of Scientific and Innovative Research
| | - Hari C. Bajaj
- Discipline of Inorganic Materials and Catalysis
- CSIR
- Central Salt and Marine Chemicals Research Institute (CSMCRI)
- Bhavnagar 364 021, India
- Academy of Scientific and Innovative Research
| |
Collapse
|
24
|
Ahmed SM, Poater A, Childers MI, Widger PCB, LaPointe AM, Lobkovsky EB, Coates GW, Cavallo L. Enantioselective polymerization of epoxides using biaryl-linked bimetallic cobalt catalysts: a mechanistic study. J Am Chem Soc 2013; 135:18901-11. [PMID: 24199614 DOI: 10.1021/ja409521z] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The enantioselective polymerization of propylene oxide (PO) using biaryl-linked bimetallic salen Co catalysts was investigated experimentally and theoretically. Five key aspects of this catalytic system were examined: (1) the structural features of the catalyst, (2) the regio- and stereoselectivity of the chain-growth step, (3) the probable oxidation and electronic state of Co during the polymerization, (4) the role of the cocatalyst, and (5) the mechanism of monomer enchainment. Several important insights were revealed. First, density functional theory (DFT) calculations provided detailed structural information regarding the regio- and stereoselective chain-growth step. Specifically, the absolute stereochemistry of the binaphthol linker determines the enantiomer preference in the polymerization, and the interaction between the salen ligand and the growing polymer chain is a fundamental aspect of enantioselectivity. Second, a new bimetallic catalyst with a conformationally flexible biphenol linker was synthesized and found to enantioselectively polymerize PO, though with lower enantioselectivity than the binaphthol linked catalysts. Third, DFT calculations revealed that the active form of the catalyst has two active exo anionic ligands (chloride or carboxylate) and an endo polymer alkoxide which can ring-open an adjacent cobalt-coordinated epoxide. Fourth, calculations showed that initiation is favored by an endo chloride ligand, while propagation is favored by the presence of two exo carboxylate ligands.
Collapse
Affiliation(s)
- Syud M Ahmed
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853-1301, United States
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Ford DD, Nielsen LPC, Zuend SJ, Musgrave CB, Jacobsen EN. Mechanistic basis for high stereoselectivity and broad substrate scope in the (salen)Co(III)-catalyzed hydrolytic kinetic resolution. J Am Chem Soc 2013; 135:15595-608. [PMID: 24041239 PMCID: PMC3875305 DOI: 10.1021/ja408027p] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In the (salen)Co(III)-catalyzed hydrolytic kinetic resolution (HKR) of terminal epoxides, the rate- and stereoselectivity-determining epoxide ring-opening step occurs by a cooperative bimetallic mechanism with one Co(III) complex acting as a Lewis acid and another serving to deliver the hydroxide nucleophile. In this paper, we analyze the basis for the extraordinarily high stereoselectivity and broad substrate scope observed in the HKR. We demonstrate that the stereochemistry of each of the two (salen)Co(III) complexes in the rate-determining transition structure is important for productive catalysis: a measurable rate of hydrolysis occurs only if the absolute stereochemistry of each of these (salen)Co(III) complexes is the same. Experimental and computational studies provide strong evidence that stereochemical communication in the HKR is mediated by the stepped conformation of the salen ligand, and not the shape of the chiral diamine backbone of the ligand. A detailed computational analysis reveals that the epoxide binds the Lewis acidic Co(III) complex in a well-defined geometry imposed by stereoelectronic rather than steric effects. This insight serves as the basis of a complete stereochemical and transition structure model that sheds light on the reasons for the broad substrate generality of the HKR.
Collapse
Affiliation(s)
- David D Ford
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | | | | | | | | |
Collapse
|
26
|
Kalow JA, Doyle AG. Enantioselective fluoride ring opening of aziridines enabled by cooperative Lewis acid catalysis. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.01.062] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
27
|
Ren WM, Wang YM, Zhang R, Jiang JY, Lu XB. Mechanistic Aspects of Metal Valence Change in SalenCo(III)OAc-Catalyzed Hydrolytic Kinetic Resolution of Racemic Epoxides. J Org Chem 2013; 78:4801-10. [DOI: 10.1021/jo400325f] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Wei-Min Ren
- State Key Laboratory of
Fine Chemicals, College of
Chemistry, Dalian University of Technology, 2 linggong road, Dalian 116024, China
| | - Yi-Ming Wang
- State Key Laboratory of
Fine Chemicals, College of
Chemistry, Dalian University of Technology, 2 linggong road, Dalian 116024, China
| | - Rong Zhang
- State Key Laboratory of
Fine Chemicals, College of
Chemistry, Dalian University of Technology, 2 linggong road, Dalian 116024, China
| | - Jing-Yang Jiang
- State Key Laboratory of
Fine Chemicals, College of
Chemistry, Dalian University of Technology, 2 linggong road, Dalian 116024, China
| | - Xiao-Bing Lu
- State Key Laboratory of
Fine Chemicals, College of
Chemistry, Dalian University of Technology, 2 linggong road, Dalian 116024, China
| |
Collapse
|
28
|
Kurahashi T, Fujii H. Unique Ligand-Radical Character of an Activated Cobalt Salen Catalyst That Is Generated by Aerobic Oxidation of a Cobalt(II) Salen Complex. Inorg Chem 2013; 52:3908-19. [DOI: 10.1021/ic302677f] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Takuya Kurahashi
- Institute for Molecular Science & Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Hiroshi Fujii
- Institute for Molecular Science & Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8787, Japan
| |
Collapse
|
29
|
Sauer DC, Kruck M, Wadepohl H, Enders M, Gade LH. Spin Density Distribution in Iron(II) and Cobalt(II) Alkyl Complexes Containing 1,3-Bis(2-pyridylimino)isoindolate Ligands. Organometallics 2013. [DOI: 10.1021/om301198b] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Désirée C. Sauer
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg,
Germany
| | - Matthias Kruck
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg,
Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg,
Germany
| | - Markus Enders
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg,
Germany
| | - Lutz H. Gade
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg,
Germany
| |
Collapse
|
30
|
Evaluation of enantiopure and non-enantiopure Co(III)-salen catalysts and their counter-ion effects in the hydrolytic kinetic resolution (HKR) of racemic epichlorohydrin. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.molcata.2012.08.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
31
|
Chemical Shift in Paramagnetic Systems. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-444-59411-2.00003-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
32
|
Jeon JY, Lee JJ, Varghese JK, Na SJ, Sujith S, Go MJ, Lee J, Ok MA, Lee BY. CO2/ethylene oxide copolymerization and ligand variation for a highly active salen–cobalt(iii) complex tethering 4 quaternary ammonium salts. Dalton Trans 2013; 42:9245-54. [DOI: 10.1039/c2dt31854g] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
33
|
Kochem A, Kanso H, Baptiste B, Arora H, Philouze C, Jarjayes O, Vezin H, Luneau D, Orio M, Thomas F. Ligand contributions to the electronic structures of the oxidized cobalt(II) salen complexes. Inorg Chem 2012; 51:10557-71. [PMID: 23013360 DOI: 10.1021/ic300763t] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Square planar cobalt(II) complexes of salen ligands N,N'-bis(3-tert-butyl-5R-salicylidene)-1,2-cyclohexanediamine), where R = OMe (1) and tert-butyl (2), were prepared. 1 and 2 were electrochemically reversibly oxidized into cations [1-H(2)O](+) and [2-H(2)O](+) in CH(2)Cl(2). The chemically generated [1-H(2)O](SbF(6))·0.68 H(2)O·0.82CH(2)Cl(2) and [2-H(2)O](SbF(6))·0.3H(2)O·0.85CH(2)Cl(2) were characterized by X-ray diffraction and NIR spectroscopy. Both complexes are paramagnetic species containing a square pyramidal cobalt ion coordinated at the apical position by an exogenous water molecule. They exhibit remarkable NIR bands at 1220 (7370 M(-1) cm(-1)) and 1060 nm (5560 M(-1) cm(-1)), respectively, assigned to a CT transition. DFT calculations and magnetic measurements confirm the paramagnetic (S = 1) ground spin state of the cations. They show that more than 70% of the total spin density in [1-H(2)O](+) and [2-H(2)O](+) is localized on the metal, the remaining spin density being distributed over the aromatic rings (30% phenoxyl character). In the presence of N-methylimidazole 1 and 2 are irreversibly oxidized by air into the genuine octahedral cobalt(III) bis(phenolate) complexes [1-im(2)](+) and [2-im(2)](+), the former being structurally characterized. Neither [1-im(2)](+) nor [2-im(2)](+) exhibits a NIR feature in its electronic spectrum. 1 and 2 were electrochemically two-electron oxidized into [1](2+) and [2](2+). The cations were identified as Co(III)-phenoxyl species by their characteristic absorption band at ca. 400 nm in the UV-vis spectrum. Coordination of the phenoxyl radical to the cobalt(III) metal ion is evidenced by the EPR signal centered at g = 2.00.
Collapse
Affiliation(s)
- Amélie Kochem
- Equipe de Chimie Inorganique Redox Biomimétique, Département de Chimie Moléculaire, Université Joseph Fourier, 38041 Grenoble Cedex 9, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Vinck E, Carter E, Murphy DM, Van Doorslaer S. Observation of an Organic Acid Mediated Spin State Transition in a Co(II)–Schiff Base Complex: An EPR, HYSCORE, and DFT Study. Inorg Chem 2012; 51:8014-24. [DOI: 10.1021/ic300058p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Evi Vinck
- Department of Physics, University of Antwerp, B-2610 Antwerp, Belgium
| | - Emma Carter
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff
CF10 3AT, United Kingdom
| | - Damien M. Murphy
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff
CF10 3AT, United Kingdom
| | | |
Collapse
|
35
|
Cyriac A, Jeon JY, Varghese JK, Park JH, Choi SY, Chung YK, Lee BY. Unusual coordination mode of tetradentate Schiff base cobalt(iii) complexes. Dalton Trans 2012; 41:1444-7. [DOI: 10.1039/c2dt11871h] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
36
|
Kalow JA, Doyle AG. Mechanistic investigations of cooperative catalysis in the enantioselective fluorination of epoxides. J Am Chem Soc 2011; 133:16001-12. [PMID: 21863842 DOI: 10.1021/ja207256s] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This report describes mechanistic studies of the (salen)Co- and amine-cocatalyzed enantioselective ring opening of epoxides by fluoride. The kinetics of the reaction, as determined by in situ (19)F NMR analysis, are characterized by apparent first-order dependence on (salen)Co. Substituent effects, nonlinear effects, and reactivity with a linked (salen)Co catalyst provide evidence for a rate-limiting, bimetallic ring-opening step. To account for these divergent data, we propose a mechanism wherein the active nucleophilic fluorine species is a cobalt fluoride that forms a resting-state dimer. Axial ligation of the amine cocatalyst to (salen)Co facilitates dimer dissociation and is the origin of the observed cooperativity. On the basis of these studies, we show that significant improvements in the rates, turnover numbers, and substrate scope of the fluoride ring-opening reactions can be realized through the use of a linked salen framework. Application of this catalyst system to a rapid (5 min) fluorination to generate the unlabeled analog of a known PET tracer, F-MISO, is reported.
Collapse
Affiliation(s)
- Julia A Kalow
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | | |
Collapse
|
37
|
Chavez SA, Martinko AJ, Lau C, Pham MN, Cheng K, Bevan DE, Mollnes TE, Yin H. Development of β-amino alcohol derivatives that inhibit Toll-like receptor 4 mediated inflammatory response as potential antiseptics. J Med Chem 2011; 54:4659-69. [PMID: 21591694 PMCID: PMC3131463 DOI: 10.1021/jm2003365] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Toll-like receptor 4 (TLR4) induced proinflammatory signaling has been directly implicated in severe sepsis and represents an attractive therapeutic target. Herein, we report our investigations into the structure-activity relationship and preliminary drug metabolism/pharmacokinetics study of β-amino alcohol derivatives that inhibit the TLR4 signaling pathway. Lead compounds were identified from in vitro cellular examination with micromolar potency for their inhibitory effects on TLR4 signaling and subsequently assessed for their ability to suppress the TLR4-induced inflammatory response in an ex vivo whole blood model. In addition, the toxicology, specificity, solubility, brain-blood barrier permeability, and drug metabolism of several compounds were evaluated. Although further optimizations are needed, our findings lay the groundwork for the future drug development of this class of small molecule agents for the treatment of severe sepsis.
Collapse
Affiliation(s)
- Sherry A. Chavez
- Department of Chemistry and Biochemistry University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Alexander J. Martinko
- Department of Chemistry and Biochemistry University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Corinna Lau
- Research Laboratory, Nordland Hospital, Bodø, Norway NO-8092
| | - Michael N. Pham
- Department of Chemistry and Biochemistry University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Kui Cheng
- Department of Chemistry and Biochemistry University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Douglas E. Bevan
- Department of Chemistry and Biochemistry University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Tom E. Mollnes
- Research Laboratory, Nordland Hospital, Bodø, Norway NO-8092
- University of Tromsø, Tromsø, Norway NO-9037
| | - Hang Yin
- Department of Chemistry and Biochemistry University of Colorado at Boulder, Boulder, CO 80309, USA
| |
Collapse
|
38
|
Roquette P, Maronna A, Reinmuth M, Kaifer E, Enders M, Himmel HJ. Combining NMR of Dynamic and Paramagnetic Molecules: Fluxional High-Spin Nickel(II) Complexes Bearing Bisguanidine Ligands. Inorg Chem 2011; 50:1942-55. [DOI: 10.1021/ic102420x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Pascal Roquette
- Contribution from the Department of Inorganic Chemistry, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Astrid Maronna
- Contribution from the Department of Inorganic Chemistry, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Matthias Reinmuth
- Contribution from the Department of Inorganic Chemistry, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Elisabeth Kaifer
- Contribution from the Department of Inorganic Chemistry, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Markus Enders
- Contribution from the Department of Inorganic Chemistry, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Hans-Jörg Himmel
- Contribution from the Department of Inorganic Chemistry, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| |
Collapse
|
39
|
Liu Y, Rawlston J, Swann AT, Takatani T, Sherrill CD, Ludovice PJ, Weck M. The bigger, the better: Ring-size effects of macrocyclic oligomeric Co(iii)-salen catalysts. Chem Sci 2011. [DOI: 10.1039/c0sc00517g] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
40
|
Carter E, Fallis IA, Kariuki BM, Morgan IR, Murphy DM, Tatchell T, Van Doorslaer S, Vinck E. Structure and pulsed EPR characterization of N,N′-bis(5-tert-butylsalicylidene)-1,2-cyclohexanediamino-vanadium(iv) oxide and its adducts with propylene oxide. Dalton Trans 2011; 40:7454-62. [DOI: 10.1039/c1dt10378d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
41
|
Vinck E, Murphy DM, Fallis IA, Strevens RR, Van Doorslaer S. Formation of a cobalt(III)-phenoxyl radical complex by acetic acid promoted aerobic oxidation of a Co(II)salen complex. Inorg Chem 2010; 49:2083-92. [PMID: 20121216 DOI: 10.1021/ic901849e] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The activation of N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamino Co(II), [Co(II)(1)], by the addition of acetic acid under aerobic conditions has been investigated by a range of spectroscopic techniques including continuous-wave EPR, HYSCORE, pulsed ENDOR, and resonance Raman. These measurements have revealed for the first time the formation of a coordinated cobalt(III)-bound phenoxyl radical labeled [Co(III)(1(*))(OAc)(n)](OAc)(m) (n = m = 1 or n = 2, m = 0). This cobalt(III)-bound phenoxyl radical is characterized by the following spin Hamiltonian parameters: g(x) = 2.0060, g(y) = 2.0031, g(z) = 1.9943, A(x) = 17 MHz, A(y) = 55 MHz, and A(z) = 14 MHz. Although the radical contains coordinated acetate(s), the experiments unambiguously proved that the phenoxyl radical is situated on ligand (1) as opposed to a phenoxyl radical ligated to cobalt in the axial position. Density functional theory computations on different models corroborate the stability of such a phenoxyl radical species and suggest the ligation of one or two acetate molecules to the complex. A mechanism is proposed, which accounts for the formation of this unusual and extremely robust phenoxyl radical, never previously observed for [Co(1)].
Collapse
Affiliation(s)
- Evi Vinck
- Department of Physics, University of Antwerp, B-2610 Antwerp, Belgium
| | | | | | | | | |
Collapse
|
42
|
Na SJ, S S, Cyriac A, Kim BE, Yoo J, Kang YK, Han SJ, Lee C, Lee BY. Elucidation of the structure of a highly active catalytic system for CO2/epoxide copolymerization: a salen-cobaltate complex of an unusual binding mode. Inorg Chem 2010; 48:10455-65. [PMID: 19780527 DOI: 10.1021/ic901584u] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Salen-type ligands comprised of ethylenediamine or 1,2-cyclohexenediamine, along with an salicylaldehyde bearing a methyl substituent on its 3-position and a -[CR(CH(2)CH(2)CH(2)N(+)Bu(3))(2)] (R = H or Me) on its 5-position, unexpectedly afford cobalt(III) complexes with uncoordinated imines. In these complexes, two salen-phenoxys and two 2,4-dinitrophenolates (DNPs), which counter the quaternary ammonium cations, coordinate persistently with cobalt, while two other DNPs are fluxional between a coordinated and an uncoordinated state in THF at room temperature. The complexes of this binding mode show excellent activities in carbon dioxide/propylene oxide copolymerization (TOF, 8300-13,000 h(-1)) but with some fluctuation in induction times (1-10 h), depending on how dry the system is. The induction time is shortened (<1.0 h) and activity is increased approximately 1.5 times upon the replacement of the two fluxional DNPs with 2,4-dinitrophenol-2,4-dinitrophenolate homoconjugation ([DNP...H...DNP](-)). Imposing steric congestion either by replacing the methyl substituent on the salicylaldehyde with tert-butyl or by employing H(2)NCMe(2)CMe(2)NH(2) instead of ethylenediamine or 1,2-cyclohexenediamine results in conventional imine-coordinating complexes, which show lower activities than uncoordinated imine complexes.
Collapse
Affiliation(s)
- Sung Jae Na
- Department of Molecular Science and Technology, Ajou University, Suwon 443-749 Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Wezenberg S, Kleij A. Cooperative Activation in the Hydrolytic Kinetic Resolution of Epoxides by a Bis-Cobalt(III)salen-Calix[4]arene Hybrid. Adv Synth Catal 2010. [DOI: 10.1002/adsc.200900673] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
44
|
Yoo J, Na SJ, Park HC, Cyriac A, Lee BY. Anion variation on a cobalt(iii) complex of salen-type ligand tethered by four quaternary ammonium salts for CO2/epoxide copolymerization. Dalton Trans 2010; 39:2622-30. [DOI: 10.1039/b920992a] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
45
|
Haak RM, Wezenberg SJ, Kleij AW. Cooperative multimetallic catalysis using metallosalens. Chem Commun (Camb) 2010; 46:2713-23. [DOI: 10.1039/c001392g] [Citation(s) in RCA: 196] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
46
|
Kurahashi T, Hada M, Fujii H. Critical role of external axial ligands in chirality amplification of trans-cyclohexane-1,2-diamine in salen complexes. J Am Chem Soc 2009; 131:12394-405. [PMID: 19705918 DOI: 10.1021/ja904635n] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of Mn(IV)(salen)(L)(2) complexes bearing different external axial ligands (L = Cl, NO(3), N(3), and OCH(2)CF(3)) from chiral salen ligands with trans-cyclohexane-1,2-diamine as a chiral scaffold are synthesized, to gain insight into conformational properties of metal salen complexes. X-ray crystal structures show that Mn(IV)(salen)(OCH(2)CF(3))(2) and Mn(IV)(salen)(N(3))(2) adopt a stepped conformation with one of two salicylidene rings pointing upward and the other pointing downward due to the bias from the trans-cyclohexane-1,2-diamine moiety, which is in clear contrast to a relatively planar solid-state conformation for Mn(IV)(salen)(Cl)(2). The CH(2)Cl(2) solution of Mn(IV)(salen)(L)(2) shows circular dichroism of increasing intensity in the order L = Cl < NO(3) << N(3) < OCH(2)CF(3), which indicates Mn(IV)(salen)(L)(2) adopts a solution conformation of an increasing chiral distortion in this order. Quantum-chemical calculations with a symmetry adapted cluster-configuration interaction method indicate that a stepped conformation exhibits more intense circular dichroism than a planar conformation. The present study clarifies an unexpected new finding that the external axial ligands (L) play a critical role in amplifying the chirality in trans-cyclohexane-1,2-diamine in Mn(IV)(salen)(L)(2) to facilitate the formation of a chirally distorted conformation, possibly a stepped conformation.
Collapse
Affiliation(s)
- Takuya Kurahashi
- Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | | | | |
Collapse
|
47
|
Ren WM, Liu ZW, Wen YQ, Zhang R, Lu XB. Mechanistic Aspects of the Copolymerization of CO2 with Epoxides Using a Thermally Stable Single-Site Cobalt(III) Catalyst. J Am Chem Soc 2009; 131:11509-18. [DOI: 10.1021/ja9033999] [Citation(s) in RCA: 276] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wei-Min Ren
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China
| | - Zhong-Wen Liu
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China
| | - Ye-Qian Wen
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China
| | - Rong Zhang
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China
| | - Xiao-Bing Lu
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China
| |
Collapse
|