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Rigamonti L, Marchi L, Fiorini V, Stagni S, Zacchini S, Pinkowicz D, Dziedzic-Kocurek K, Forni A, Muniz Miranda F, Mazzoni R. Trapping an unprecedented octacoordinated iron(II) complex with neutral bis-tetrazolylpyridyl ligands and solvent molecules. Dalton Trans 2024; 53:3490-3498. [PMID: 38270176 DOI: 10.1039/d3dt04026g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
Iron(II) can show a very rich coordination chemistry with concomitant modulation of its properties as promising functional materials. Metalation of the neutral tridentate nitrogen-donor mer-coordinating ligand 2,6-bis(2-(methyl)-2H-tetrazol-5-yl)pyridine (Me2btp) with Fe(ClO4)2·6H2O through accurate solvent polarity control enables the selective crystallization of [FeHS/LS(Me2btp)2](ClO4)2·MeCN·2.75H2O (2HS/LS·MeCN·2.75H2O) as red rods, where half of the iron(II) centres resides in the low spin (LS, S = 0) state and the other half is in the high spin (HS, S = 2) state. The red rods spontaneously convert into yellow crystals once removed from the mother liquor and exposed to air due to solvent rearrangement within the crystal packing; these new crystals can be assigned to [FeHS(Me2btp)2](ClO4)2·solvent (2HS·solvent) where all the iron(II) centres are now blocked in the HS state, as confirmed by magnetic measurements. The polarity of the crystallization solvent, together with the maintenance of the crystals within the mother liquor, are pivotal for the reactivity and interconversion of different species. Indeed, upon long standing in solution, 2HS/LS·MeCN·2.75H2O converts to another form of red crystals belonging to [FeLS(Me2btp)2][FeHS(Me2btp)(MeCN)2(H2O)](ClO4)4·MeCN (2LS·3HS·MeCN), as confirmed by single crystal X-ray diffraction data. In this co-crystal, the iron(II) in 2 resides in the LS state at all temperatures while the iron(II) in 3 is blocked in the HS state. Well-formed yellow crystals could be also isolated among the red crystals of 2HS/LS·MeCN·2.75H2O, and they could be identified as the unprecedented octacoordinated species [Fe(Me2btp)2(MeCN)(H2O)](ClO4)2·H2O (1·H2O) by single-crystal X-ray diffraction. These yellow crystals are stable in the air, but slowly convert into 2LS·3HS·MeCN if kept in the mother liquor for about one week. 1·H2O can be considered the trapped intermediate in the solid state during the conversion of [FeHS(Me2btp)2]2+ into [FeHS(Me2btp)(MeCN)2(H2O)]2+ in solution, where the two tridentate ligands in the starting species can unfold to accommodate coordinated MeCN and H2O molecules, as confirmed by theoretical calculations, and eventually one of the two Me2btp is completely replaced by the solvent.
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Affiliation(s)
- Luca Rigamonti
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy.
| | - Lorenzo Marchi
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy.
| | - Valentina Fiorini
- Dipartimento di Chimica Industriale 'Toso Montanari', Università degli Studi di Bologna, Via Gobetti 85, 40129 Bologna, Italy
| | - Stefano Stagni
- Dipartimento di Chimica Industriale 'Toso Montanari', Università degli Studi di Bologna, Via Gobetti 85, 40129 Bologna, Italy
| | - Stefano Zacchini
- Dipartimento di Chimica Industriale 'Toso Montanari', Università degli Studi di Bologna, Via Gobetti 85, 40129 Bologna, Italy
| | - Dawid Pinkowicz
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Katarzyna Dziedzic-Kocurek
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Stanisława Łojasiewicza 11, Kraków 30-348, Poland
| | - Alessandra Forni
- Consiglio Nazionale delle Ricerche, Istituto di Scienze e Tecnologie Chimiche "G. Natta" (CNR-SCITEC) and INSTM RU of Milan, via C. Golgi 19, 20133 Milano, Italy
| | - Francesco Muniz Miranda
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy.
| | - Rita Mazzoni
- Dipartimento di Chimica Industriale 'Toso Montanari', Università degli Studi di Bologna, Via Gobetti 85, 40129 Bologna, Italy
- Center for Chemical Catalysis - C3, Università degli Studi di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
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Cingolani A, Olivieri D, Messori A, Cesari C, Zanotti V, Zacchini S, Gualandi I, Scavetta E, Mariani F, Tonelli D, Mazzoni R. Electrochemical Polymerisation of Newly Synthesised 3,4-Ethylene Dioxythiophene-N-Heterocyclic Carbene Iron Complexes and Application as Redox Mediators. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.121138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Guo WX, shen Z, Su YF, Li K, Lin WQ, Chen GH, Guan J, Wang XM, Li Z, Yu Z, Zou Z. Iron-N-Heterocyclic Carbene Complexes as Efficient Electrocatalysts for Water Oxidation in Acidic Conditions. Dalton Trans 2022; 51:12494-12501. [DOI: 10.1039/d2dt01474b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The development of stable, earth-abundant, and high-activity molecular water oxidation catalysts in acidic and neutral conditions remains a great challenge. Here, the use of N-heterocyclic carbene (NHC)-based iron(III) complex 1...
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Moccia F, Rigamonti L, Messori A, Zanotti V, Mazzoni R. Bringing Homogeneous Iron Catalysts on the Heterogeneous Side: Solutions for Immobilization. Molecules 2021; 26:2728. [PMID: 34066456 PMCID: PMC8124704 DOI: 10.3390/molecules26092728] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/23/2021] [Accepted: 05/03/2021] [Indexed: 11/16/2022] Open
Abstract
Noble metal catalysts currently dominate the landscape of chemical synthesis, but cheaper and less toxic derivatives are recently emerging as more sustainable solutions. Iron is among the possible alternative metals due to its biocompatibility and exceptional versatility. Nowadays, iron catalysts work essentially in homogeneous conditions, while heterogeneous catalysts would be better performing and more desirable systems for a broad industrial application. In this review, approaches for heterogenization of iron catalysts reported in the literature within the last two decades are summarized, and utility and critical points are discussed. The immobilization on silica of bis(arylimine)pyridyl iron complexes, good catalysts in the polymerization of olefins, is the first useful heterogeneous strategy described. Microporous molecular sieves also proved to be good iron catalyst carriers, able to provide confined geometries where olefin polymerization can occur. Same immobilizing supports (e.g., MCM-41 and MCM-48) are suitable for anchoring iron-based catalysts for styrene, cyclohexene and cyclohexane oxidation. Another excellent example is the anchoring to a Merrifield resin of an FeII-anthranilic acid complex, active in the catalytic reaction of urea with alcohols and amines for the synthesis of carbamates and N-substituted ureas, respectively. A SILP (Supported Ionic Liquid Phase) catalytic system has been successfully employed for the heterogenization of a chemoselective iron catalyst active in aldehyde hydrogenation. Finally, FeIII ions supported on polyvinylpyridine grafted chitosan made a useful heterogeneous catalytic system for C-H bond activation.
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Affiliation(s)
- Fabio Moccia
- Dipartimento di Chimica Industriale “Toso Montanari”, Università degli Studi di Bologna, viale Risorgimento 4, 40136 Bologna, Italy; (F.M.); (A.M.); (V.Z.)
| | - Luca Rigamonti
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy;
| | - Alessandro Messori
- Dipartimento di Chimica Industriale “Toso Montanari”, Università degli Studi di Bologna, viale Risorgimento 4, 40136 Bologna, Italy; (F.M.); (A.M.); (V.Z.)
| | - Valerio Zanotti
- Dipartimento di Chimica Industriale “Toso Montanari”, Università degli Studi di Bologna, viale Risorgimento 4, 40136 Bologna, Italy; (F.M.); (A.M.); (V.Z.)
| | - Rita Mazzoni
- Dipartimento di Chimica Industriale “Toso Montanari”, Università degli Studi di Bologna, viale Risorgimento 4, 40136 Bologna, Italy; (F.M.); (A.M.); (V.Z.)
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