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Hellinghuizen MA, Franceschi P, Roithová J. Is the E/Z Iminium Ratio a Good Enantioselectivity Predictor in Iminium Catalysis? Chemistry 2024:e202400294. [PMID: 38884393 DOI: 10.1002/chem.202400294] [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: 01/23/2024] [Revised: 05/27/2024] [Accepted: 06/17/2024] [Indexed: 06/18/2024]
Abstract
Developing new enantioselective reactions is an important part of chemical discovery but requires time and resources to test large arrays of potential reaction conditions. New techniques are required to analyse many different reactions quickly and efficiently. Mass spectrometry is a high-throughput method; when combined with ion-mobility spectrometry, this technique can monitor diastereomeric reaction intermediates and thus be a handle to study enantioselective reactions. Through this technique and others, it was noted before that in the organocatalytic 1,4-addition to α,β-unsaturated aldehydes, the abundance of initial diastereomeric intermediates correlates strongly to that of the final enantiomeric products. This work determines isomeric abundance for various catalysts and aldehydes and uses it to predict the enantiomeric excess of two control reactions. The prediction matches well for one reaction but does not predict the obtained results for the second. This finding confirms that the E/Z ratio of the iminium intermediates can be used as a predictor for some reactions, but the kinetics of the following steps can dramatically change the true enantioselectivity.
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Affiliation(s)
- Matthijs A Hellinghuizen
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525AJ, Nijmegen, The Netherlands
| | - Pietro Franceschi
- Research and Innovation Centre, Fondazione E. Mach, Via Edmund Mach, 1, 38098, San Michele All'adige TN, Italy
| | - Jana Roithová
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525AJ, Nijmegen, The Netherlands
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Briš A, Baltussen MG, Tripodi GL, Huck WTS, Franceschi P, Roithová J. Direct Analysis of Complex Reaction Mixtures: Formose Reaction. Angew Chem Int Ed Engl 2024; 63:e202316621. [PMID: 38100204 DOI: 10.1002/anie.202316621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Indexed: 12/31/2023]
Abstract
Complex reaction mixtures, like those postulated on early Earth, present an analytical challenge because of the number of components, their similarity, and vastly different concentrations. Interpreting the reaction networks is typically based on simplified or partial data, limiting our insight. We present a new approach based on online monitoring of reaction mixtures formed by the formose reaction by ion-mobility-separation mass-spectrometry. Monitoring the reaction mixtures led to large data sets that we analyzed by non-negative matrix factorization, thereby identifying ion-signal groups capturing the time evolution of the network. The groups comprised ≈300 major ion signals corresponding to sugar-calcium complexes formed during the formose reaction. Multivariate analysis of the kinetic profiles of these complexes provided an overview of the interconnected kinetic processes in the solution, highlighting different pathways for sugar growth and the effects of different initiators on the initial kinetics. Reconstructing the network's topology further, we revealed so far unnoticed fast retro-aldol reaction of ketoses, which significantly affects the initial reaction dynamics. We also detected the onset of sugar-backbone branching for C6 sugars and cyclization reactions starting for C5 sugars. This top-down analytical approach opens a new way to analyze complex dynamic mixtures online with unprecedented coverage and time resolution.
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Affiliation(s)
- Anamarija Briš
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525, AJ Nijmegen, The Netherlands
- Laboratory for physical-organic chemistry, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička c. 54, 10000, Zagreb, Croatia
| | - Mathieu G Baltussen
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525, AJ Nijmegen, The Netherlands
| | - Guilherme L Tripodi
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525, AJ Nijmegen, The Netherlands
| | - Wilhelm T S Huck
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525, AJ Nijmegen, The Netherlands
| | - Pietro Franceschi
- Research and innovation Centre, Fondazione E. Mach, Via Edmund Mach, 1, 38098, San Michele All'adige TN, Italy
| | - Jana Roithová
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525, AJ Nijmegen, The Netherlands
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Ibáñez-Ibáñez L, Mollar-Cuni A, Apaloo-Messan E, Sharma AK, Mata JA, Maseras F, Vicent C. Ion mobility mass spectrometry uncovers regioselectivity in the carboxylate-assisted C-H activation of palladium N-heterocyclic carbene complexes. Dalton Trans 2024; 53:656-665. [PMID: 38073605 DOI: 10.1039/d3dt02793g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Carboxylate-assisted Pd-catalyzed C-H bond activation constitutes a mild and versatile synthetic tool to efficiently and selectively cleave inert C-H bonds. Herein, we demonstrate a simple method to experimentally evaluate both reactivity and selectivity in such systems using mass spectrometry (MS) methods. The N-heterocyclic carbene (NHC) cations [(NHC)PdX]+, bearing as X- ligand bases commonly used to promote the C-H activation (carboxylates and bicarbonate), are generated in the gas-phase by ESI-MS. Their C-H bond activation at the N-bound groups of the NHC is then studied using Collision Induced Dissociation (CID) experiments. Ion Mobility Spectrometry (IM)-MS is exploited to identify a number of regioisomers associated with the distinctive site selective C-H activations. It is demonstrated that such C-H activation concomitant with acetic acid release occurs from a mixture of activated [(NHC-H)Pd(CH3CO2H)]+ and non-activated [(NHC)Pd(CH3CO2)]+ complexes. The identity of the X-type ligands (X = Cl-, carboxylates and bicarbonate) has a significant impact on the regioisomer branching ratio upon CID conditions. IM-MS in conjunction with a DFT mechanistic study is presented for the acetate-assisted C-H activation of the [(NHC)Pd(CH3CO2)]+ cation featuring butyl and aryl as N-donor groups.
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Affiliation(s)
- Laura Ibáñez-Ibáñez
- Institute of Advanced Materials (INAM), Net of organometallic chemistry for sustainable solutions (OASIS), Universitat Jaume I, Avda. Sos Baynat s/n, 12071, Castellón, Spain.
| | - Andres Mollar-Cuni
- Institute of Advanced Materials (INAM), Net of organometallic chemistry for sustainable solutions (OASIS), Universitat Jaume I, Avda. Sos Baynat s/n, 12071, Castellón, Spain.
| | - Edmond Apaloo-Messan
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Avgda. Països Catalans, 16, 43007 Tarragona, Spain.
| | - Akhilesh K Sharma
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Avgda. Països Catalans, 16, 43007 Tarragona, Spain.
| | - Jose A Mata
- Institute of Advanced Materials (INAM), Net of organometallic chemistry for sustainable solutions (OASIS), Universitat Jaume I, Avda. Sos Baynat s/n, 12071, Castellón, Spain.
| | - Feliu Maseras
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Avgda. Països Catalans, 16, 43007 Tarragona, Spain.
| | - Cristian Vicent
- Serveis Centrals d'Instrumentació Científica (SCIC). Universitat Jaume I, Avda. Sos Baynat s/n, 12071, Castellón, Spain.
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Yang J, Tripodi GL, Derks MTGM, Seo MS, Lee YM, Southwell KW, Shearer J, Roithová J, Nam W. Generation, Spectroscopic Characterization, and Computational Analysis of a Six-Coordinate Cobalt(III)-Imidyl Complex with an Unusual S = 3/2 Ground State that Promotes N-Group and Hydrogen Atom-Transfer Reactions with Exogenous Substrates. J Am Chem Soc 2023; 145:26106-26121. [PMID: 37997643 PMCID: PMC11175169 DOI: 10.1021/jacs.3c08117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
We report the synthesis and characterization of a mononuclear nonheme cobalt(III)-imidyl complex, [Co(NTs)(TQA)(OTf)]+ (1), with an S = 3/2 spin state that is capable of facilitating exogenous substrate modifications. Complex 1 was generated from the reaction of CoII(TQA)(OTf)2 with PhINTs at -20 °C. A flow setup with ESI-MS detection was used to explore the kinetics of the formation, stability, and degradation pathway of 1 in solution by treating the Co(II) precursor with PhINTs. Co K-edge XAS data revealed a distinct shift in the Co K-edge compared to the Co(II) precursor, in agreement with the formation of a Co(III) intermediate. The unusual S = 3/2 spin state was proposed based on EPR, DFT, and CASSCF calculations and Co Kβ XES results. Co K-edge XAS and IR photodissociation (IRPD) spectroscopies demonstrate that 1 is a six-coordinate species, and IRPD and resonance Raman spectroscopies are consistent with 1 being exclusively the isomer with the NT ligand occupying the vacant site trans to the TQA aliphatic amine nitrogen atom. Electronic structure calculations (broken symmetry DFT and CASSCF/NEVPT2) demonstrate an S = 3/2 oxidation state resulting from the strong antiferromagnetic coupling of an •NTs spin to the high-spin S = 2 Co(III) center. Reactivity studies of 1 with PPh3 derivatives revealed its electrophilic characteristic in the nitrene-transfer reaction. While the activation of C-H bonds by 1 was proved to be kinetically challenging, 1 could oxidize weak O-H and N-H bonds. Complex 1 is, therefore, a rare example of a Co(III)-imidyl complex capable of exogenous substrate transformations.
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Affiliation(s)
- Jindou Yang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Guilherme L. Tripodi
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Max T. G. M. Derks
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Kendal W. Southwell
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Jana Roithová
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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Duez Q, Tinnemans P, Elemans JAAW, Roithová J. Kinetics of ligand exchange in solution: a quantitative mass spectrometry approach. Chem Sci 2023; 14:9759-9769. [PMID: 37736645 PMCID: PMC10510763 DOI: 10.1039/d3sc03342b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 08/24/2023] [Indexed: 09/23/2023] Open
Abstract
Complex speciation and exchange kinetics of labile ligands are critical parameters for understanding the reactivity of metal complexes in solution. We present a novel approach to determine ligand exchange parameters based on electrospray ionization mass spectrometry (ESI-MS). The introduction of isotopically labelled ligands to a solution of metal host and unlabelled ligands allows the quantitative investigation of the solution-phase equilibria. Furthermore, ion mobility separation can target individual isomers, such as ligands bound at specific sites. As a proof of concept, we investigate the solution equilibria of labile pyridine ligands coordinated in the cavity of macrocyclic porphyrin cage complexes bearing diamagnetic or paramagnetic metal centres. The effects of solvent, porphyrin coordination sphere, transition metal, and counterion on ligand dissociation are discussed. Rate constants and activation parameters for ligand dissociation in the solution can be derived from our ESI-MS approach, thereby providing mechanistic insights that are not easily obtained from traditional solution-phase techniques.
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Affiliation(s)
- Quentin Duez
- Radboud University, Institute for Molecules and Materials Heyendaalseweg 135 6525 AJ Nijmegen The Netherlands
| | - Paul Tinnemans
- Radboud University, Institute for Molecules and Materials Heyendaalseweg 135 6525 AJ Nijmegen The Netherlands
| | - Johannes A A W Elemans
- Radboud University, Institute for Molecules and Materials Heyendaalseweg 135 6525 AJ Nijmegen The Netherlands
| | - Jana Roithová
- Radboud University, Institute for Molecules and Materials Heyendaalseweg 135 6525 AJ Nijmegen The Netherlands
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Affiliation(s)
- Hai-Long Qian
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China.,Institute of Analytical Food Safety, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Shu-Ting Xu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China.,Institute of Analytical Food Safety, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Xiu-Ping Yan
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China.,Institute of Analytical Food Safety, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.,Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China
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Mollar-Cuni A, Ibáñez-Ibáñez L, Guisado-Barrios G, Mata JA, Vicent C. Introducing Ion Mobility Mass Spectrometry to Identify Site-Selective C-H Bond Activation in N-Heterocyclic Carbene Metal Complexes. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:2291-2300. [PMID: 36374280 DOI: 10.1021/jasms.2c00257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The activation of C-H bonds in a selective manner still constitutes a major challenge from a synthetic point of view; thus, it remains an active area of fundamental and applied research. Herein, we introduce ion mobility spectrometry mass spectrometry-based (IM-MS) approaches to uncover site-selective C-H bond activation in a series of metal complexes of general formula [(NHC)LMCl]+ (NHC = N-heterocyclic carbene; L = pentamethylcyclopentadiene (Cp*) or p-cymene; M = Pd, Ru, and Ir). The C-H bond activation at the N-bound groups of the NHC ligand is promoted upon collision induced dissociation (CID). The identification of the resulting [(NHC-H)LM]+ isomers relies on the distinctive topology that such cyclometalated isomers adopt upon site-selective C-H bond activation. Such topological differences can be reliably evidenced as different mobility peaks in their respective CID-IM mass spectra. Alternative isomers are also identified via dehydrogenation at the Cp*/p-cymene (L) ligands to afford [(NHC)(L-H)M]+. The fragmentation of the ion mobility-resolved peaks is also investigated by CID-IM-CID. It enables the assignment of mobility peaks to the specific isomers formed from C(sp2)-H or C(sp3)-H bond activation and distinguishes them from the Cp*/p-cymene (L) dehydrogenation isomers. The conformational change of the NHC ligands upon C-H bond activation, concomitant with cyclometalation, is also discussed on the basis of the estimated collision cross section (CCS). A unique conformation change of the pyrene-tagged NHC members is identified that involves the reorientation of the NHC ring accompanied by a folding of the pyrene moiety.
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Affiliation(s)
- Andrés Mollar-Cuni
- Institute of Advanced Materials (INAM), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Jaume I, Avda. Sos Baynat s/n, 12071, Castellón, Spain
| | - Laura Ibáñez-Ibáñez
- Institute of Advanced Materials (INAM), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Jaume I, Avda. Sos Baynat s/n, 12071, Castellón, Spain
| | - Gregorio Guisado-Barrios
- Departamento de Química Inorgánica. Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, 50009Zaragoza, Spain
| | - Jose A Mata
- Institute of Advanced Materials (INAM), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Jaume I, Avda. Sos Baynat s/n, 12071, Castellón, Spain
| | - Cristian Vicent
- Serveis Centrals d'Intrumentació Científica (SCIC). Universitat Jaume I, Avda. Sos Baynat s/n, 12071Castellón, Spain
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