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Hulushe ST, Watkins GM, Khanye SD. A cobalt(II) coordination polymer-derived catalyst engineered via temperature-induced semi-reversible single-crystal-to-single-crystal (SCSC) dehydration for efficient liquid-phase epoxidation of olefins. Dalton Trans 2024. [PMID: 38899354 DOI: 10.1039/d4dt00739e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Single-crystal-to-single-crystal (SCSC) transformations provide more avenues for phase transitions, which have piqued great interest in crystal engineering. In this work, a 3D Co(II)-based coordination polymer (CP), {Co2(OH2)8(btec)}·4H2O (1), (where (btec)4- = 1,2,4,5-benzenetetracarboxylate) undergoes SCSC transition upon heating at 180 °C to afford an anhydrous phase [Co2(btec)] (1'). Room-temperature water-vapour induced semi-reversible SCSC transformation of 1' involves condensation of two water molecules coordinating to the metal cluster, yielding a new framework [Co2(OH2)2(btec)] (2). These SCSC transitions were accomplished through a sequential bond breaking and new bond formation process which was accompanied by colour changes from orange (1) → violet (1') → pink (2). All materials were structurally elucidated by single-crystal X-ray diffraction (SCXRD) and further established by various analytical techniques. According to SCXRD data, all the frameworks possess octahedral geometries around the cobalt(II) sphere. SCXRD studies further revealed that 1 is a polymeric architecture with a binodal 4-c sql topology while 1' and 2 possess (3,6)-c kgd and (4,6)-c scu 3D nets, respectively. By virtue of multitopicity exhibited by the tetracarboxylate, the coordination number of the linker around the Co(II) sphere increased from four (in 1) to eight (in 1') and then decreased to six (in 2). Most interestingly, permanent porosity could be observed for the dihydrate 2, originated from potential void space as substantiated by dinitrogen (N2) sorption isotherm. These porous frameworks were active catalysts for the aerobic epoxidation of the model substrate cyclohexene using molecular oxygen (O2) as the final oxidant in the presence of the sacrificial i-butyraldehyde (IBA) reductant. For using the dihydrous phase 2, cyclohexene and various other olefins were catalytically oxidised to their corresponding epoxides with up to 38.5% conversion and 99.0% selectivity. The catalyst 2 can be expediently recycled in four runs without significant loss of activity. This research demonstrates that a little innovation in the active-site-engineered organic-inorganic hybrid materials can significantly enhance the catalytic performance and selectivity of coordination polymer-derived heterogeneous catalysts.
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Affiliation(s)
- Siya T Hulushe
- Department of Chemistry, Rhodes University, Makhanda 6139, South Africa.
| | - Gareth M Watkins
- Department of Chemistry, Rhodes University, Makhanda 6139, South Africa.
| | - Setshaba D Khanye
- Division of Pharmaceutical Chemistry, Faculty of Pharmacy, Rhodes University, Makhanda 6139, South Africa
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Yelin S, Cula B, Limberg C. Low‐coordinated iron(II) siloxide complexes – structural diversity and reactivity towards O2 and oxygen atom transfer reagents. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202200078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Stefan Yelin
- Humboldt-Universität zu Berlin: Humboldt-Universitat zu Berlin Department of chemistry GERMANY
| | - Beatrice Cula
- Humboldt University of Berlin Campus Berlin: Humboldt-Universitat zu Berlin Campus Adlershof Department of chemistry GERMANY
| | - Christian Limberg
- Humboldt-Universität zu Berlin: Humboldt-Universitat zu Berlin Department of Chemistry Brook-Taylor-Str. 2 12489 Berlin GERMANY
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Ar D, Kilpatrick AFR, Cula B, Herwig C, Limberg C. Transformation of Formazanate at Nickel(II) Centers to Give a Singly Reduced Nickel Complex with Azoiminate Radical Ligands and Its Reactivity toward Dioxygen. Inorg Chem 2021; 60:13844-13853. [PMID: 33770441 DOI: 10.1021/acs.inorgchem.0c03761] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The heteroleptic (formazanato)nickel bromide complex LNi(μ-Br)2NiL [LH = Mes-NH-N═C(p-tol)-N═N-Mes] has been prepared by deprotonation of LH with NaH followed by reaction with NiBr2(dme). Treatment of this complex with KC8 led to transformation of the formazanate into azoiminate ligands via N-N bond cleavage and the simultaneous release of aniline. At the same time, the potentially resulting intermediate complex L'2Ni [L' = HN═C(p-tol)-N═N-Mes] was reduced by one additional electron, which is delocalized across the π system and the metal center. The resulting reduced complex [L'2Ni]K(18-c-6) has a S = 1/2 ground state and a square-planar structure. It reacts with dioxygen via one-electron oxidation to give the complex L'2Ni, and the formation of superoxide was detected spectroscopically. If oxidizable substrates are present during this process, these are oxygenated/oxidized. Triphenylphosphine is converted to phosphine oxide, and hydrogen atoms are abstracted from TEMPO-H and phenols. In the case of cyclohexene, autoxidations are triggered, leading to the typical radical-chain-derived products of cyclohexene.
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Affiliation(s)
- Deniz Ar
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Alexander F R Kilpatrick
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Beatrice Cula
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Christian Herwig
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Christian Limberg
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
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Ponchai P, Adpakpang K, Bureekaew S. Selective cyclohexene oxidation to allylic compounds over a Cu-triazole framework via homolytic activation of hydrogen peroxide. Dalton Trans 2021; 50:7917-7921. [PMID: 33969847 DOI: 10.1039/d1dt00227a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Utilization of metal-organic frameworks as heterogeneous catalysts is crucial owing to their abundant catalytic sites and well-defined porous structures. Highly robust [Cu3(trz)3(μ3-OH)(OH)2(H2O)4]·2H2O (trz = 1,2,4-triazole) was employed as a catalyst for liquid-phase cyclohexene oxidation with hydrogen peroxide (H2O2). Possessing the porous structure together with Lewis acid attributes from the triangular [Cu3(trz)3(μ3-OH)] center, selective oxidation of cyclohexene to allylic products gives a molar yield of 31% with 87% selectivity. According to the highly selective allylic production, the reaction over the present Cu-MOF plausibly occurs via homolytic activation of H2O2. This finding elucidates the unique features of the MOF for efficient catalysis of cyclohexene oxidation.
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Affiliation(s)
- Panyapat Ponchai
- School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong 21210, Thailand.
| | - Kanyaporn Adpakpang
- School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong 21210, Thailand.
| | - Sareeya Bureekaew
- School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong 21210, Thailand. and Research Network of NANOTEC-VISTEC on Nanotechnology for Energy, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong 21210, Thailand
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Solvothermal synthesis, crystal structure of a new Ca(II) coordination polymer [CaII(4–ABA)(CH3COO)(H2O)(DMF)]n and its catalytic epoxidation of cyclohexene. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.129074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Mal DD, Kundu J, Pradhan D. CuO{001} as the Most Active Exposed Facet for Allylic Oxidation of Cyclohexene via a Greener Route. ChemCatChem 2021. [DOI: 10.1002/cctc.202001645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Diptangshu Datta Mal
- Materials Science Centre Indian Institute of Technology Kharagpur WB 721302 India
| | - Joyjit Kundu
- Materials Science Centre Indian Institute of Technology Kharagpur WB 721302 India
| | - Debabrata Pradhan
- Materials Science Centre Indian Institute of Technology Kharagpur WB 721302 India
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Rao BG, Sudarsanam P, Rao TV, Amin MH, Bhargava SK, Reddy BM. Highly Dispersed MnOx Nanoparticles on Shape-Controlled SiO2 Spheres for Ecofriendly Selective Allylic Oxidation of Cyclohexene. Catal Letters 2020. [DOI: 10.1007/s10562-020-03205-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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8
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Thermodynamics of complex formation in dimethylsulfoxide: The case of Co(II) complexes with nitrogen donor ligands and their O2 adducts. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.04.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Cancino P, Santibañez L, Fuentealba P, Olea C, Vega A, Spodine E. Heterometallic Cu II/Ln III polymers active in the catalytic aerobic oxidation of cycloalkenes under solvent-free conditions. Dalton Trans 2018; 47:13360-13367. [PMID: 30065994 DOI: 10.1039/c8dt01913d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Heterometallic 3d-4f inorganic polymers were prepared using 3,5 pyridinedicarboxylic acid (H2PDC), {[CuLn2(PDC)2(SO4)2(H2O)6]·H2O}n (Ln: SmIII, CuSmPDC, EuIII, CuEuPDC, GdIII, and CuGdPDC). These catalysts are active in the aerobic oxidation of cycloalkenes under solvent-free conditions, with a conversion for the oxidation of cyclohexene of 71% after one hour of the reaction, and a TOF value of 1438 h-1 for CuSmPDC. On the other hand, the oxidation of cycloheptene and cyclooctene exhibited slightly lower conversions of 52% and 47%, and TOF values of 1053 and 159 h-1 after 1 and 6 hours of the reaction, respectively. The radical mechanism for the oxidation reaction of cyclohexene was assessed by Raman and EPR spectroscopy. The first evidenced the formation of Cu-O2 adducts and the second permitted is to observe the presence of the oxygen centered radical species, which act as initiators of the reaction chain to generate the products. An increase in the temperature of the reaction correlates with the adduct formation, and with the enhancement of the oxidation reaction.
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Affiliation(s)
- P Cancino
- Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
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Recent advances on controllable and selective catalytic oxidation of cyclohexene. CHINESE JOURNAL OF CATALYSIS 2018. [DOI: 10.1016/s1872-2067(18)63050-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Denekamp IM, Antens M, Slot TK, Rothenberg G. Selective Catalytic Oxidation of Cyclohexene with Molecular Oxygen: Radical Versus Nonradical Pathways. ChemCatChem 2018; 10:1035-1041. [PMID: 29610628 PMCID: PMC5873426 DOI: 10.1002/cctc.201701538] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/23/2017] [Indexed: 12/18/2022]
Abstract
We study the allylic oxidation of cyclohexene with O2 under mild conditions in the presence of transition‐metal catalysts. The catalysts comprise nanometric metal oxide particles supported on porous N‐doped carbons (M/N:C, M=V, Cr, Fe, Co, Ni, Cu, Nb, Mo, W). Most of these metal oxides give only moderate conversions, and the majority of the products are over‐oxidation products. Co/N:C and Cu/N:C, however, give 70–80 % conversion and 40–50 % selectivity to the ketone product, cyclohexene‐2‐one. Control experiments in which we used free‐radical scavengers show that the oxidation follows the expected free‐radical pathway in almost all cases. Surprisingly, the catalytic cycle in the presence of Cu/N:C does not involve free‐radical species in solution. Optimisation of this catalyst gives >85 % conversion with >60 % selectivity to the allylic ketone at 70 °C and 10 bar O2. We used SEM, X‐ray photoelectron spectroscopy and XRD to show that the active particles have a cupric oxide/cuprous oxide core–shell structure, giving a high turnover frequency of approximately 1500 h−1. We attribute the high performance of this Cu/N:C catalyst to a facile surface reaction between adsorbed cyclohexenyl hydroperoxide molecules and activated oxygen species.
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Affiliation(s)
- Ilse M Denekamp
- Van't Hoff Institute for Molecular Sciences University of Amsterdam Science Park 904 Amsterdam1098 XH The Netherlands
| | - Martijn Antens
- Van't Hoff Institute for Molecular Sciences University of Amsterdam Science Park 904 Amsterdam1098 XH The Netherlands
| | - Thierry K Slot
- Van't Hoff Institute for Molecular Sciences University of Amsterdam Science Park 904 Amsterdam1098 XH The Netherlands
| | - Gadi Rothenberg
- Van't Hoff Institute for Molecular Sciences University of Amsterdam Science Park 904 Amsterdam1098 XH The Netherlands
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Govinda Rao B, Sudarsanam P, Nallappareddy P, Yugandhar Reddy M, Venkateshwar Rao T, Reddy BM. Selective allylic oxidation of cyclohexene catalyzed by nanostructured Ce-Sm-Si materials. CATAL COMMUN 2017. [DOI: 10.1016/j.catcom.2017.07.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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