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Open AccessArticle

Design and Construction of Novel Frustrated Lewis Pairs Based on Modified Lewis Acid B(C₆F₅)₃

by Quanwei Wang, Zonggui Li, Yanuo Cui, Jiashuo Zhang, Huilin Li and Wei Li

Crystals 2026, 16(4), 236; https://doi.org/10.3390/cryst16040236 - 2 Apr 2026

Viewed by 459

This study aims to systematically investigate the influence of substituent effects on the strength of Lewis acid–base interactions in frustrated Lewis pairs (FLPs). Specifically, -C₆F₅ groups of the classical Lewis acid B(C₆F₅)₃ are sequentially replaced [...] Read more.

This study aims to systematically investigate the influence of substituent effects on the strength of Lewis acid–base interactions in frustrated Lewis pairs (FLPs). Specifically, -C₆F₅ groups of the classical Lewis acid B(C₆F₅)₃ are sequentially replaced with -C₆Cl₅, -C₆Br₅, and -C₆I₅ groups, and the Lewis acids are paired with the Lewis base 1,3-disubstituted imidazol-2-ylidene (ItBu) to form FLPs. Further energy decomposition analysis (sobEDA), orbital analysis, and molecular fragment density difference (MFDD) analysis reveal the nature of the substituent effect on the interaction energy (∆Eint) of the FLPs. The research findings indicate that the ∆Eint of B(C₆F₅)3-ItBu, B(C₆F₅)_x(C₆Y₅)_3−x-ItBu (x = 0, 1, 2; Y = Cl, Br, I) originates mainly from the interaction between the outermost halogen atom of the Lewis acid and the central carbon (C) atom of the Lewis base, rather than from the interaction between the central atoms boron (B) and carbon (C). This mechanism ultimately leads to a ∆Eint for B(C₆F₅)₂(C₆Y₅)-ItBu (Y = Cl, Br, I) that is comparable to that of B(C₆F₅)₃-ItBu. This indicates that modified B(C₆F₅)₂(C₆Y₅) (Y = Cl, Br, I) exhibits greater potential for the construction of novel FLPs. Full article

(This article belongs to the Section Crystal Engineering)

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21 pages, 2431 KB

Open AccessArticle

Pyridyl-Thiourea Ruthenium and Osmium Complexes: Coordination of Ligand and Application as FLP Hydrogenation Catalysts

by Alejandro Grasa, Roisin D. Leavey, Fernando Viguri, Ricardo Rodríguez and Pilar Lamata

Molecules 2025, 30(16), 3398; https://doi.org/10.3390/molecules30163398 - 16 Aug 2025

Viewed by 1314

Abstract

Pyridyl-thiourea complexes of formula [(Cym)MCl(κ²N_py,S-H₂NNS)][SbF₆] (Cym = η⁶-p-MeC₆H₄iPr; H₂NNS = N-(p-tolyl)-N′-(2-pyridylmethyl)thiourea); M = Ru ( [...] Read more.

Pyridyl-thiourea complexes of formula [(Cym)MCl(κ²N_py,S-H₂NNS)][SbF₆] (Cym = η⁶-p-MeC₆H₄iPr; H₂NNS = N-(p-tolyl)-N′-(2-pyridylmethyl)thiourea); M = Ru (1), Os (2)) were synthesized by reacting the corresponding metal dimers [{(Cym)MCl}₂(μ-Cl)₂] with H₂NNS in the presence of NaSbF₆. Subsequent chloride abstraction with AgSbF₆, followed by NH deprotonation using NaHCO₃, afforded the cationic complexes [(Cym)M(κ³N_py,N_amide,S-HNNS)][SbF₆] (M = Ru (5a), (5c); M = Os (6a, 6c)) and [(Cym)M(κ²N_amide,S-HNNS)][SbF₆] (M = Ru (5b); M = Os (6b)). The proposed structures for the prepared compounds are based on NMR data. Complexes 5a, 5b, and 6a, 6b evolve to the thermodynamically more stable species 5c and 6c, respectively, in which the deprotonated ligand HNNS adopts a κ³N_py,N_amide,S coordination mode. Complexes 5c and 6c activate H₂, behaving as frustrated Lewis pair (FLP) species, and catalyze (5c and/or 6c) the hydrogenation of polar multiple bonds, including the C=N bonds of N-benzylideneaniline and quinoline, the C=C bond of methyl acrylate, and the C=O bond of 2,2,2-trifluoroacetophenone. Full article

(This article belongs to the Special Issue Recent Advances in Transition Metal Catalysis, 2nd Edition)

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16 pages, 7087 KB

Open AccessEditor’s ChoiceArticle

Hydrochar Loaded with Nitrogen-Containing Functional Groups for Versatile Removal of Cationic and Anionic Dyes and Aqueous Heavy Metals

by Yue Zhang, Yongshan Wan, Yulin Zheng, Yicheng Yang, Jinsheng Huang, Hao Chen, Jianjun Chen, Ahmed Mosa and Bin Gao

Water 2024, 16(23), 3387; https://doi.org/10.3390/w16233387 - 25 Nov 2024

Cited by 8 | Viewed by 2871

Abstract

Developing novel sorbents for effective removal of heavy metals and organic dyes from industrial wastewater remains a central theme for water research. We modified hydrochar derived from the hydrothermal carbonization of wheat straw at 180 °C with 3-Aminopropyl triethoxysilane (APTES) to enhance its [...] Read more.

Developing novel sorbents for effective removal of heavy metals and organic dyes from industrial wastewater remains a central theme for water research. We modified hydrochar derived from the hydrothermal carbonization of wheat straw at 180 °C with 3-Aminopropyl triethoxysilane (APTES) to enhance its versatile adsorption of Pb(II), Cu(II), methylene blue (MB), and reactive red (Red). Pristine and modified hydrochar (HyC and APTES-HyC) were characterized and tested for sorption performance. Characterization results revealed an enriched presence of N-functional groups, mainly -NH₂ and C-N, on APTES-HyC, in addition to an increased specific surface area from 1.14 m²/g (HyC) to 4.51 m²/g. APTES-HyC exhibited a faster adsorption rate than HyC, reaching equilibrium approximately 4 h after initiation. The Langmuir adsorption capacities of APTES-HyC were 49.6, 14.8, 31.7, and 18.3 mg/g for Pb(II), Cu(II), MB, and Red, respectively, about 8.5, 5.0, 1.3, and 9.5 times higher than for HyC. The enhanced adsorption performance of APTES-HyC is attributed to the increased N-functional groups, which facilitated adsorption mechanisms specific to the pollutant of concern such as formation of frustrated Lewis pairs and cation–π interactions for metal ions and π–π interactions and hydrogen bond for dyes. This study offers a novel and facile approach to the synthesis of N-doped carbon materials for practical applications. Full article

(This article belongs to the Section Wastewater Treatment and Reuse)

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18 pages, 4998 KB

Open AccessReview

Lewis Acid-Initiated Ring-Opening Reactions of Five- and Six-Membered Cyclic Ethers Based on the Oxonium Ylide Intermediates

by Dandan Jiang, Jun Xiao, Yingzhen Zhang, Kunming Liu, Juanhua Li and Jinbiao Liu

Organics 2024, 5(3), 219-236; https://doi.org/10.3390/org5030011 - 22 Jul 2024

Cited by 3 | Viewed by 5779

Abstract

In light of the small ring strain of five/six-membered cyclic ethers, constructing complex molecules via ring-opening reactions has consistently been a highly challenging topic in organic synthesis. Induced by Lewis acids, the charge redistribution in cyclic ethers forms oxonium ylide intermediates, thereby activating [...] Read more.

In light of the small ring strain of five/six-membered cyclic ethers, constructing complex molecules via ring-opening reactions has consistently been a highly challenging topic in organic synthesis. Induced by Lewis acids, the charge redistribution in cyclic ethers forms oxonium ylide intermediates, thereby activating the C–O bond and subsequently facilitating nucleophilic attack for ring opening. In recent years, a variety of novel Lewis acids, encompassing those with new metal centers and frustrated Lewis pairs (FLPs), have been effectively utilized to induce the formation of oxonium ylides, offering a diverse array of methods for the ring opening of five/six-membered cyclic ethers. This review conveys the extensive application advancements of diverse Lewis acid types for cyclic ether ring-opening reactions over the past two decades, originating from the perspective of the classification of Lewis acids. Furthermore, the substrate applicability and chemical transformation efficiency of these Lewis acids in the ring-opening reactions of cyclic ethers have also been discussed herein. Full article

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18 pages, 4753 KB

Open AccessReview

Advances in Catalysts for Urea Electrosynthesis Utilizing CO₂ and Nitrogenous Materials: A Mechanistic Perspective

by Mengfei Zhang, Tianjian Feng, Xuanming Che, Yuhan Wang, Pengxian Wang, Mao Chai and Menglei Yuan

Materials 2024, 17(9), 2142; https://doi.org/10.3390/ma17092142 - 3 May 2024

Cited by 4 | Viewed by 4352

Abstract

Electrocatalytic urea synthesis from CO₂ and nitrogenous substances represents an essential advance for the chemical industry, enabling the efficient utilization of resources and promoting sustainable development. However, the development of electrocatalytic urea synthesis has been severely limited by weak chemisorption, poor activation [...] Read more.

Electrocatalytic urea synthesis from CO₂ and nitrogenous substances represents an essential advance for the chemical industry, enabling the efficient utilization of resources and promoting sustainable development. However, the development of electrocatalytic urea synthesis has been severely limited by weak chemisorption, poor activation and difficulties in C–N coupling reactions. In this review, catalysts and corresponding reaction mechanisms in the emerging fields of bimetallic catalysts, MXenes, frustrated Lewis acid–base pairs and heterostructures are summarized in terms of the two central mechanisms of molecule–catalyst interactions as well as chemical bond cleavage and directional coupling, which provide new perspectives for improving the efficiency of electrocatalytic synthesis of urea. This review provides valuable insights to elucidate potential electrocatalytic mechanisms. Full article

(This article belongs to the Section Green Materials)

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13 pages, 2523 KB

Open AccessEditor’s ChoiceArticle

Alkane Elimination Preparation of Heterobimetallic MoAl Tetranuclear and Binuclear Complexes Promoting THF Ring Opening

by Léon Escomel, Erwann Jeanneau, Chloé Thieuleux and Clément Camp

Inorganics 2024, 12(3), 72; https://doi.org/10.3390/inorganics12030072 - 28 Feb 2024

Cited by 5 | Viewed by 3279

Abstract

We report a straightforward alkane elimination strategy to prepare well-defined heterobimetallic Al/Mo species. Notably, the reaction of the monohydride complex of molybdenum, Cp*MoH(CO)₃, with triisobutyl aluminum affords a new heterobimetallic [MoAl]₂ tetranuclear compound, [Cp*Mo(CO)(µ-CO)₂Al(ⁱBu)₂] [...] Read more.

We report a straightforward alkane elimination strategy to prepare well-defined heterobimetallic Al/Mo species. Notably, the reaction of the monohydride complex of molybdenum, Cp*MoH(CO)₃, with triisobutyl aluminum affords a new heterobimetallic [MoAl]₂ tetranuclear compound, [Cp*Mo(CO)(µ-CO)₂Al(ⁱBu)₂]₂, (1), featuring a 12-membered C₄O₄Mo₂Al₂ ring in which isocarbonyls bridge the Mo and Al centers. The addition of pyridine to this complex successfully results in the dissociation of the dimer into a new discrete binuclear complex, [Cp*Mo(CO)₂(µ-CO)Al(Py)(iBu)₂], (2). Switching the nature of the Lewis base from pyridine to tetrahydrofuran does not lead to the THF analogue of adduct 2, but rather to a complex reaction where one of the identified products corresponds to a tetranuclear species, [Cp*Mo(CO)₃(μ-CH₂CH₂CH₂CH₂O)Al(iBu)₂]₂, (3), featuring two bridging alkoxybutyl fragments originating from the C-O ring opening of THF. Compound 3 adds to the unusual occurrences of THF ring opening by heterobimetallic complexes, which is evocative of masked metal-only frustrated Lewis pair behavior and highlights the high reactivity of these Al/Mo assemblies. Full article

(This article belongs to the Special Issue Binuclear Complexes II)

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13 pages, 1729 KB

Open AccessArticle

Systematic Assessment of the Catalytic Reactivity of Frustrated Lewis Pairs in C-H Bond Activation

by Yongjie Guo, Xueqi Lian, Hao Zhang, Xueling Zhang, Jun Chen, Changzhong Chen, Xiaobing Lan and Youxiang Shao

Molecules 2024, 29(1), 24; https://doi.org/10.3390/molecules29010024 - 19 Dec 2023

Cited by 3 | Viewed by 3294

Abstract

Unreactive C-H bond activation is a new horizon for frustrated Lewis pair (FLP) chemistry. This study provides a systematic assessment of the catalytic reactivity of recently reported intra-molecular FLPs on the activation of typical inert C-H bonds, including 1-methylpyrrole, methane, benzyl, propylene, and [...] Read more.

Unreactive C-H bond activation is a new horizon for frustrated Lewis pair (FLP) chemistry. This study provides a systematic assessment of the catalytic reactivity of recently reported intra-molecular FLPs on the activation of typical inert C-H bonds, including 1-methylpyrrole, methane, benzyl, propylene, and benzene, in terms of density functional theory (DFT) calculations. The reactivity of FLPs is evaluated according to the calculated reaction thermodynamic and energy barriers of C-H bond activation processes in the framework of concerted C-H activation mechanisms. As for 1-methylpyrrole, 14 types of N-B-based and 15 types of P-B-based FLPs are proposed to be active. Although none of the evaluated FLPs are able to catalyze the C-H activation of methane, benzyl, or propylene, four types of N-B-based FLPs are suggested to be capable of catalyzing the activation of benzene. Moreover, the influence of the strength of Lewis acid (LA) and Lewis base (LB), and the differences between the influences of LA and LB on the catalytic reactivity of FLPs, are also discussed briefly. This systematic assessment of the catalytic activity of FLPs should provide valuable guidelines to aid the development of efficient FLP-based metal-free catalysts for C-H bond activation. Full article

(This article belongs to the Special Issue π-Conjugated Functional Molecules & Polymers)

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12 pages, 4053 KB

Open AccessArticle

The Construction of Surface-Frustrated Lewis Pair Sites to Improve the Nitrogen Reduction Catalytic Activity of In₂O₃

by Mingqian Wang, Ming Zheng, Yuchen Sima, Chade Lv and Xin Zhou

Molecules 2023, 28(20), 7130; https://doi.org/10.3390/molecules28207130 - 17 Oct 2023

Cited by 2 | Viewed by 2690

Abstract

The construction of a surface-frustrated Lewis pairs (SFLPs) structure is expected to break the single electronic state restriction of catalytic centers of P-region element materials, due to the existence of acid-base and basic active canters without mutual quenching in the SFLPs system. Herein, [...] Read more.

The construction of a surface-frustrated Lewis pairs (SFLPs) structure is expected to break the single electronic state restriction of catalytic centers of P-region element materials, due to the existence of acid-base and basic active canters without mutual quenching in the SFLPs system. Herein, we have constructed eight possible SFLPS structures on the In₂O₃ (110) surface by doping non-metallic elements and investigated their performance as electrocatalytic nitrogen reduction catalysts using density functional theory (DFT) calculations. The results show that P atom doping (P@In₂O₃) can effectively construct the structure of SFLPs, and the doped P atom and In atom near the vacancy act as Lewis base and acid, respectively. The P@In₂O₃ catalyst can effectively activate N₂ molecules through the enzymatic mechanism with a limiting potential of −0.28 eV and can effectively suppress the hydrogen evolution reaction (HER). Electronic structure analysis also confirmed that the SFLPs site can efficiently capture N₂ molecules and activate N≡N bonds through a unique “donation-acceptance” mechanism. Full article

(This article belongs to the Special Issue Advanced Materials for Energy Conversion and Water Sustainability)

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17 pages, 3705 KB

Open AccessReview

Triphenylborane in Metal-Free Catalysis

by Suresh Mummadi and Clemens Krempner

Molecules 2023, 28(3), 1340; https://doi.org/10.3390/molecules28031340 - 31 Jan 2023

Cited by 13 | Viewed by 5537

Abstract

The development and application of new organoboron reagents as Lewis acids in synthesis and metal-free catalysis have dramatically expanded over the past 20 years. In this context, we will show the recent uses of the simple and relatively weak Lewis acid BPh₃ [...] Read more.

The development and application of new organoboron reagents as Lewis acids in synthesis and metal-free catalysis have dramatically expanded over the past 20 years. In this context, we will show the recent uses of the simple and relatively weak Lewis acid BPh₃—discovered 100 years ago—as a metal-free catalyst for various organic transformations. The first part will highlight catalytic applications in polymer synthesis such as the copolymerization of epoxides with CO₂, isocyanate, and organic anhydrides to various polycarbonate copolymers and controlled diblock copolymers as well as alternating polyurethanes. This is followed by a discussion of BPh₃ as a Lewis acid component in the frustrated Lewis pair (FLP) mediated cleavage of hydrogen and hydrogenation catalysis. In addition, BPh₃-catalyzed reductive N-methylations and C-methylations with CO₂ and silane to value-added organic products will be covered as well along with BPh₃-catalyzed cycloadditions and insertion reactions. Collectively, this mini-review showcases the underexplored potential of commercially available BPh₃ in metal-free catalysis. Full article

(This article belongs to the Special Issue Featured Reviews in Organometallic Chemistry)

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12 pages, 3232 KB

Open AccessArticle

Nonoxidative Coupling of Methane to Produce C₂ Hydrocarbons on FLPs of an Albite Surface

by Yannan Zhou, Ye Chen, Xuegang Luo and Xin Wang

Molecules 2023, 28(3), 1037; https://doi.org/10.3390/molecules28031037 - 19 Jan 2023

Cited by 4 | Viewed by 2551

Abstract

The characteristics of active sites on the surface of albite were theoretically analyzed by density functional theory, and the activation of the C-H bond of methane using an albite catalyst and the reaction mechanism of preparing C₂ hydrocarbons by nonoxidative coupling were [...] Read more.

The characteristics of active sites on the surface of albite were theoretically analyzed by density functional theory, and the activation of the C-H bond of methane using an albite catalyst and the reaction mechanism of preparing C₂ hydrocarbons by nonoxidative coupling were studied. There are two frustrated Lewis pairs (FLPs) on the (001) and (010) surfaces of albite; they can dissociate H₂ under mild conditions and show high activity for the activation of methane C-H bonds. CH₄ molecules can undergo direct dissociative adsorption on the (010) surface, whereas a 50.07 kJ/mol activation barrier is needed on the (001) surface. The prepared albite catalyst has a double combination function of the (001) and (010) surfaces; these surfaces produce a spillover phenomenon in the process of CH₄ activation reactions, where CH₃ overflows from the (001) surface with CH₃ adsorbed on the (010) surface to achieve nonoxidative high efficiently C-C coupling with an activation energy of 18.51 kJ/mol. At the same time, this spillover phenomenon inhibits deep dehydrogenation, which is conducive to the selectivity of the C₂ hydrocarbons. The experimental results confirm that the selectivity of the C₂ hydrocarbons is maintained above 99% in the temperature range of 873 K to 1173 K. Full article

(This article belongs to the Topic Theoretical, Quantum and Computational Chemistry)

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10 pages, 4143 KB

Open AccessCommunication

Reactivity and Stability of a Ring-Expanded N-Heterocyclic Carbene Copper(I) Boryl Imidinate

by Rex S. C. Charman, Thomas M. Horsley Downie, Thomas H. Jerome, Mary F. Mahon and David J. Liptrot

Inorganics 2022, 10(9), 135; https://doi.org/10.3390/inorganics10090135 - 7 Sep 2022

Cited by 3 | Viewed by 2694

Abstract

Frustrated Lewis pairs (FLPs) have evolved from a revolutionary concept to widely applied catalysts. We recently reported the ring-expanded N-heterocyclic carbene supported copper(I) boryliminomethanide, (6-Dipp)CuC(=N^tBu)Bpin and noted it reacted with heterocumulenes in a fashion reminiscent of FLPs. We thus set out [...] Read more.

Frustrated Lewis pairs (FLPs) have evolved from a revolutionary concept to widely applied catalysts. We recently reported the ring-expanded N-heterocyclic carbene supported copper(I) boryliminomethanide, (6-Dipp)CuC(=N^tBu)Bpin and noted it reacted with heterocumulenes in a fashion reminiscent of FLPs. We thus set out to explore its reactivity with a range of other substrates known to react with FLPs. This was undertaken by a series of synthetic studies using NMR spectroscopy, mass spectrometry, IR spectroscopy, and single crystal X-ray crystallography. (6-Dipp)CuC(=N^tBu)Bpin was investigated for its reactivity towards water, hydrogen, and phenylacetylene. Its solution stability was also explored. Upon heating, (6-Dipp)CuC(=N^tBu)Bpin decomposed to (6-Dipp)CuCN, which was characterised by SC-XRD and NMR spectroscopy, and pinB^tBu. Although no reaction was observed with hydrogen, (6-Dipp)CuC(=N^tBu)Bpin reacted with water to form (6-Dipp)CuC(=N(H)^tBu)B(OH)pin, which was structurally characterised. In contrast to its FLP-reminiscent heterolytic cleavage reactivity towards water, (6-Dipp)CuC(=N^tBu)Bpin acted as a Brønsted base towards phenyl acetylene generating (6-Dipp)CuCCPh, which was characterised by SC-XRD, IR, and NMR spectroscopy, and HC(=N^tBu)Bpin Full article

(This article belongs to the Special Issue Synergy between Main Group and Transition Metal Chemistry)

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13 pages, 3637 KB

Open AccessArticle

Nucleophilic Substitution at a Coordinatively Saturated Five-Membered NHC∙Haloborane Centre

by Gargi Kundu, Srinu Tothadi and Sakya S. Sen

Inorganics 2022, 10(7), 97; https://doi.org/10.3390/inorganics10070097 - 7 Jul 2022

Cited by 6 | Viewed by 3543

Abstract

In this paper, we have used a saturated five-membered N-Heterocyclic carbene (5SIDipp = 1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-ylidine) for the synthesis of SNHC-haloboranes adducts and their further nucleophilic substitutions to put unusual functional groups at the central boron atom. The reaction of 5-SIDipp with RBCl₂ yields [...] Read more.

In this paper, we have used a saturated five-membered N-Heterocyclic carbene (5SIDipp = 1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-ylidine) for the synthesis of SNHC-haloboranes adducts and their further nucleophilic substitutions to put unusual functional groups at the central boron atom. The reaction of 5-SIDipp with RBCl₂ yields Lewis-base adducts, 5-SIDipp·RBCl₂ [R = H (1), Ph (2)]. The hydrolysis of 1 gives the NHC stabilized boric acid, 5-SIDipp·B(OH)₃ (3), selectively. Replacement of chlorine atoms from 1 and 2 with one equivalent of AgOTf led to the formation of 5-SIDipp·HBCl(OTf) (4) and 5-SIDipp·PhBCl(OTf) (5a), where all the substituents on the boron atoms are different. The addition of two equivalents of AgNO₃ to 2 leads to the formation of rare di-nitro substituted 5-SIDipp·BPh(NO₃)₂ (6). Further, the reaction of 5-SIDipp with B(C₆F₅)₃ in tetrahydrofuran and diethyl ether shows a frustrated Lewis pair type small molecule activated products, 7 and 8. Full article

(This article belongs to the Special Issue Fifth Element: The Current State of Boron Chemistry)

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15 pages, 4767 KB

Open AccessReview

Frustrated Lewis Pairs in Heterogeneous Catalysis: Theoretical Insights

by Qiang Wan, Sen Lin and Hua Guo

Molecules 2022, 27(12), 3734; https://doi.org/10.3390/molecules27123734 - 10 Jun 2022

Cited by 23 | Viewed by 5237

Abstract

Frustrated Lewis pair (FLP) catalysts have attracted much recent interest because of their exceptional ability to activate small molecules in homogeneous catalysis. In the past ten years, this unique catalysis concept has been extended to heterogeneous catalysis, with much success. Herein, we review [...] Read more.

Frustrated Lewis pair (FLP) catalysts have attracted much recent interest because of their exceptional ability to activate small molecules in homogeneous catalysis. In the past ten years, this unique catalysis concept has been extended to heterogeneous catalysis, with much success. Herein, we review the recent theoretical advances in understanding FLP-based heterogeneous catalysis in several applications, including metal oxides, functionalized surfaces, and two-dimensional materials. A better understanding of the details of the catalytic mechanism can help in the experimental design of novel heterogeneous FLP catalysts. Full article

(This article belongs to the Special Issue A Commemorative Special Issue Honoring Professor Donald Truhlar)

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19 pages, 7109 KB

Open AccessReview

Activation of Small Molecules and Hydrogenation of CO₂ Catalyzed by Frustrated Lewis Pairs

by Ranita Pal, Manas Ghara and Pratim Kumar Chattaraj

Catalysts 2022, 12(2), 201; https://doi.org/10.3390/catal12020201 - 7 Feb 2022

Cited by 35 | Viewed by 10854

Abstract

The chemistry of frustrated Lewis pair (FLP) is widely explored in the activation of small molecules, the hydrogenation of CO₂, and unsaturated organic species. A survey of several experimental works on the activation of small molecules by FLPs and the related [...] Read more.

The chemistry of frustrated Lewis pair (FLP) is widely explored in the activation of small molecules, the hydrogenation of CO₂, and unsaturated organic species. A survey of several experimental works on the activation of small molecules by FLPs and the related mechanistic insights into their reactivity from electronic structure theory calculation are provided in the present review, along with the catalytic hydrogenation of CO₂. The mechanistic insight into H₂ activation is thoroughly discussed, which may provide a guideline to design more efficient FLP for H₂ activation. FLPs can activate other small molecules like, CO, NO, CO₂, SO₂, N₂O, alkenes, alkynes, etc. by cooperative action of the Lewis centers of FLPs, as revealed by several computational analyses. The activation barrier of H₂ and other small molecules by the FLP can be decreased by utilizing the aromaticity criterion in the FLP as demonstrated by the nucleus independent chemical shift (NICS) analysis. The term boron-ligand cooperation (BLC), which is analogous to the metal-ligand cooperation (MLC), is invoked to describe a distinct class of reactivity of some specific FLPs towards H₂ activation. Full article

(This article belongs to the Special Issue Catalytic Hydrogenation of CO₂)

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12 pages, 4689 KB

Open AccessFeature PaperArticle

Cu/O Frustrated Lewis Pairs on Cu Doped CeO₂(111) for Acetylene Hydrogenation: A First-Principles Study

by Shulan Zhou, Qiang Wan and Sen Lin

Catalysts 2022, 12(1), 74; https://doi.org/10.3390/catal12010074 - 10 Jan 2022

Cited by 12 | Viewed by 3901

Abstract

In this work, the H₂ dissociation and acetylene hydrogenation on Cu doped CeO₂(111) were studied using density functional theory calculations. The results indicated that Cu doping promotes the formation of oxygen vacancy (O_v) which creates Cu/O and Ce/O [...] Read more.

In this work, the H₂ dissociation and acetylene hydrogenation on Cu doped CeO₂(111) were studied using density functional theory calculations. The results indicated that Cu doping promotes the formation of oxygen vacancy (O_v) which creates Cu/O and Ce/O frustrated Lewis pairs (FLPs). With the help of Cu/O FLP, H₂ dissociation can firstly proceed via a heterolytic mechanism to produce Cu-H and O-H by overcoming a barrier of 0.40 eV. The H on Cu can facilely migrate to a nearby oxygen to form another O-H species with a barrier of 0.43 eV. The rate-determining barrier is lower than that for homolytic dissociation of H₂ which produces two O-H species. C₂H₂ hydrogenation can proceed with a rate-determining barrier of 1.00 eV at the presence of Cu-H and O-H species., While C₂H₂ can be catalyzed by two O-H groups with a rate-determining barrier of 1.06 eV, which is significantly lower than that (2.86 eV) of C₂H₂ hydrogenated by O-H groups on the bare CeO₂(111), showing the high activity of Cu doped CeO₂(111) for acetylene hydrogenation. In addition, the rate-determining barrier of C₂H₄ further hydrogenated by two O-H groups is 1.53 eV, much higher than its desorption energy (0.72 eV), suggesting the high selectivity of Cu doped CeO₂(111) for C₂H₂ partial hydrogenation. This provides new insights to develop effective hydrogenation catalysts based on metal oxide. Full article

(This article belongs to the Special Issue 10th Anniversary of Catalysts: Achievements in Computational Catalysis Techniques and Applications)

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