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Inchausti A, Mollfulleda R, Swart M, Perles J, Herrero S, Baonza VG, Taravillo M, Lobato Á. Torsion Effects Beyond the δ Bond and the Role of π Metal-Ligand Interactions. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2401293. [PMID: 38569515 PMCID: PMC11220682 DOI: 10.1002/advs.202401293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/19/2024] [Indexed: 04/05/2024]
Abstract
Previous studies on bimetallic paddlewheel compounds have established a direct correlation between metal-metal distance and ligand torsion angles, leading to the rule that higher torsion results in longer metal-metal bond distances. Here, the new discovery based on diarylformamidinate Ru₂⁵⁺ paddlewheel compounds [Ru2Cl(DArF)4] that show an opposite behavior is reported: higher torsions lead to shorter metal-metal distances. This discovery challenges the assumption that internal rotation solely impacts the δ bond. By combining experimental and theoretical techniques, it is demostrated that this trend is associated with previously overlooked π metal-ligand interactions. These π metal-ligand interactions are a direct consequence of the paddlewheel structure and the conjugated nature of the bidentate ligands. This findings offer far-reaching insights into the influence of equatorial ligands and their π-conjugation characteristics on the electronic properties of paddlewheel complexes. That this effect is not exclusive of diruthenium compounds but also occurs in other bimetallic cores such as ditungsten or dirhodium is demonstrated, and with other ligands showing allyl type conjugation. These results provide a novel approach for fine-tuning the properties of these compounds with significant implications for materials design.
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Affiliation(s)
- Almudena Inchausti
- MALTA‐Consolider Team and Departamento de Química FísicaUniversidad Complutense de MadridPlz. Ciencias 2MadridE‐28040Spain
| | - Rosa Mollfulleda
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de QuímicaUniversitat de Girona, Campus de MontiliviParc UdGCataloniaGironaE–17003Spain
| | - Marcel Swart
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de QuímicaUniversitat de Girona, Campus de MontiliviParc UdGCataloniaGironaE–17003Spain
- ICREA Pg. Lluís Companys 23Barcelona08010Spain
| | - Josefina Perles
- Laboratorio de Difracción de Rayos X de MonocristalServicio Interdepartamental de Investigación, Universidad Autónoma de MadridMadridE‐28049Spain
| | - Santiago Herrero
- MatMoPol Research Group, Departamento de Química InorgánicaUniversidad Complutense de MadridPlz. Ciencias 2MadridE‐28040Spain
| | - Valentín G. Baonza
- MALTA‐Consolider Team and Departamento de Química FísicaUniversidad Complutense de MadridPlz. Ciencias 2MadridE‐28040Spain
| | - Mercedes Taravillo
- MALTA‐Consolider Team and Departamento de Química FísicaUniversidad Complutense de MadridPlz. Ciencias 2MadridE‐28040Spain
| | - Álvaro Lobato
- MALTA‐Consolider Team and Departamento de Química FísicaUniversidad Complutense de MadridPlz. Ciencias 2MadridE‐28040Spain
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Hashem K, Krishnan R, Yang K, Anjali BA, Zhang Y, Jiang J. Computational design of metal hydrides on a defective metal-organic framework HKUST-1 for ethylene dimerization. Phys Chem Chem Phys 2024; 26:7109-7123. [PMID: 38348573 DOI: 10.1039/d3cp06257k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Catalytic ethylene dimerization to 1-butene is a crucial reaction in the chemical industry, as 1-butene is used for the production of most common plastics (e.g., polyethylene). With well-defined tuneable structures and unsaturated active sites, defective metal-organic frameworks have recently emerged as potential catalysts for ethylene dimerization. Herein, we computationally design a series of metal hydrides on defective HKUST-1 namely H-M-DHKUST-1 (M: Co, Ni, Cu, Ru, Rh and Pd), and subsequently assess their catalytic activity for ethylene dimerization by density functional theory calculations. Due to the antiferromagnetic behavior of dimeric metal-based clusters, we comprehensively investigate all possible multiplicity states on H-M-DHKUST-1 and observe multiplicity crossing. The ground-state reaction barriers for four elementary steps (initiation, C-C coupling, β-hydride elimination and 1-butene desorption) are rationalized and C-C coupling is revealed to be the rate-determining step on H-Co-, H-Ni-, H-Ru-, H-Rh- and H-Pd-DHKUST-1. The energy barrier for β-hydride elimination is found to be the lowest on H-Ru- and H-Rh-DHKUST-1, attributed to the weak stability of agostic arrangement; however, the energy barrier for 1-butene desorption is the highest on H-Rh-DHKUST-1. Among the designed H-M-DHKUST-1, Co- and Ni-based ones are predicted to exhibit the best overall catalytic performance. The mechanistic insights from this study may facilitate the development of new MOFs toward efficient ethylene dimerization and other industrially important reactions.
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Affiliation(s)
- Karam Hashem
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 117576, Singapore.
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 1 Pasek Road Jurong Island, 627833, Singapore
| | - Ramakrishna Krishnan
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 117576, Singapore.
| | - Kuiwei Yang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 117576, Singapore.
| | - Bai Amutha Anjali
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 117576, Singapore.
| | - Yugen Zhang
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 1 Pasek Road Jurong Island, 627833, Singapore
| | - Jianwen Jiang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 117576, Singapore.
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3
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Miller-Clark LA, Christ PE, Barbarini BT, Ren T. Bisaryl and Bisalkynyl Diruthenium (III,III) Compounds Based on an Electron-Deficient Building Block. Inorg Chem 2022; 61:14871-14879. [PMID: 36082487 DOI: 10.1021/acs.inorgchem.2c02498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reported herein is a new series of diruthenium(III,III) bisalkynyl and bisaryl diruthenium(III,III) compounds supported with 2-amino-3-(trifluoromethyl)pyridinate (amtfmp). Using Ru2(amtfmp)4Cl2 from a modified preparation, cis 2:2 Ru2(amtfmp)4(C≡CPh)2 (1), cis 2:2 Ru2(amtfmp)4(Ph)2 (2), and 3:1 Ru2(amtfmp)4(Ph)2 (3) were synthesized via a lithium-halogen exchange reaction using LiC2Ph and LiPh, respectively. Compounds 1-3 are all Ru2(III,III) species with a ground-state configuration of π4δ2(π*)4 (S = 0) and were characterized via mass spectrometry, electron absorption and 1H/19F NMR spectroscopies, and voltammetry. The molecular structures of 1-3 were established using single-crystal X-ray diffraction analysis, and preliminary density functional theory analysis was performed to elaborate the electronic structures of 1 and 2. Comparisons of the electrochemical properties of 1-3 against the Ru2(amtfmp)4Cl2 starting material reveal cathodic shifts of the Ru27+/6+ oxidation and the Ru26+/5+ and Ru25+/4+ reduction potentials. In comparison to related Ru2(III,III) bisalkynyl and bisaryl compounds, the electrode potentials for 1-3 are anodically shifted up to ca. 0.95 V, highlighting the strong electron-withdrawing nature of the amtfmp ligand.
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Affiliation(s)
- Lyndsy A Miller-Clark
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Peter E Christ
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Brian T Barbarini
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tong Ren
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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4
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Winter RF, Mang A, Linseis M. Synthesis and crystal structures of rhodium acetate paddle‐wheel complexes with anchor group‐functionalized and hydrogen bond‐supported axial ligands. Z Anorg Allg Chem 2022. [DOI: 10.1002/zaac.202200199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | - André Mang
- Fachbereich Chemie, Universität Konstanz Fachbereich Chemie, Universität Konstanz Universitätsstraße 10 78464 Konstanz GERMANY
| | - Michael Linseis
- Fachbereich Chemie, Universität Konstanz Fachbereich Chemie, Universität Konstanz Universitätsstraße 10 78464 Konstanz GERMANY
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5
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Roy MD, Trenerry MJ, Thakuri B, MacMillan SN, Liptak MD, Lancaster KM, Berry JF. Electronic Structure of Ru 26+ Complexes with Electron-Rich Anilinopyridinate Ligands. Inorg Chem 2022; 61:3443-3457. [PMID: 35175754 DOI: 10.1021/acs.inorgchem.1c03346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Diruthenium paddlewheel complexes supported by electron-rich anilinopyridinate (Xap) ligands were synthesized in the course of the first in-depth structural and spectroscopic interrogation of monocationic [Ru2(Xap)4Cl]+ species in the Ru26+ oxidation state. Despite paramagnetism of the compounds, 1H NMR spectroscopy proved highly informative for determining the isomerism of the Ru25+ and Ru26+ compounds. While most compounds are found to have the polar (4,0) geometry, with all four Xap ligands in the same orientation, some synthetic procedures resulted in a mixture of (4,0) and (3,1) isomers, most notably in the case of the parent compound Ru2(ap)4Cl. The isomerism of this compound has been overlooked in previous reports. Electrochemical studies demonstrate that oxidation potentials can be tuned by the installation of electron donating groups to the ligands, increasing accessibility of the Ru26+ oxidation state. The resulting Ru26+ monocations were found to have the expected (π*)2 ground state, and an in-depth study of the electronic transitions by Vis/NIR absorption and MCD spectroscopies with the aid of TD-DFT allowed for the assignment of the electronic spectra. The empty δ* orbital is the major acceptor orbital for the most prominent electronic transitions. Both Ru25+ and Ru26+ compounds were studied by Ru K-edge X-ray absorption spectroscopy; however, the rising edge energy is insensitive to redox changes in the compounds due to the broad line shape observed for 4d transition metal K-edges. DFT calculations indicate the presence of ligand orbitals at the frontier level, suggesting that further oxidation beyond Ru26+ will be ligand-centered rather than metal-centered.
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Affiliation(s)
- Michael D Roy
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Michael J Trenerry
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Biswash Thakuri
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405, United States
| | - Samantha N MacMillan
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Matthew D Liptak
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405, United States
| | - Kyle M Lancaster
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - John F Berry
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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6
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Miller-Clark LA, Christ PE, Ren T. Diruthenium aryl compounds - tuning of electrochemical responses and solubility. Dalton Trans 2021; 51:580-586. [PMID: 34904616 DOI: 10.1039/d1dt03957a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reported herein are the two new series of diruthenium aryl compounds: Ru2(DiMeOap)4(Ar) (1a-6a) (DiMeOap = 2-(3,5-dimethoxyanilino)pyridinate) and Ru2(m-iPrOap)4(Ar) (1b-5b) (m-iPrOap = 2-(3-iso-propoxyanilino)pyridinate), prepared through the lithium-halogen exchange reaction with a variety of aryl halides (Ar = C6H4-4-NMe2 (1), C6H4-4-tBu (2), C6H4-4-OMe (3), C6H3-3,5-(OMe)2 (4), C6H4-4-CF3 (5), C6H5 (6)). The molecular structures of these compounds were established with X-ray diffraction studies. Additionally, these compounds were characterized using electronic absorption and voltammetric techniques. Compounds 1a-6a and 1b-5b are all in the Ru25+ oxidation state, with a ground state configuration of σ2π4δ2(π*δ*)3 (S = 3/2). Use of the modified ap ligands (ap') resulted in moderate increases of product yield when compared to the unsubstituted Ru2(ap)4(Ar) (ap = 2-anilinopyridinate) series. Comparisons of the electrochemical properties of 1a-6a and 1b-5b against the Ru2(ap')Cl starting material reveals the addition of the aryl ligand cathodically shifted the Ru26+/5+ oxidation and Ru25+/4+ reduction potentials. These oxidation and reductions potentials are also strongly dependent on the p-substituent of the axial aryl ligands.
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Affiliation(s)
| | - Peter E Christ
- Department of Chemistry, Purdue University, West Lafayette, Indiana 4790, USA.
| | - Tong Ren
- Department of Chemistry, Purdue University, West Lafayette, Indiana 4790, USA.
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7
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Ogawa S, Chattopadhyay S, Tanaka Y, Ohto T, Tada T, Tada H, Fujii S, Nishino T, Akita M. Control of dominant conduction orbitals by peripheral substituents in paddle-wheel diruthenium alkynyl molecular junctions. Chem Sci 2021; 12:10871-10877. [PMID: 34476066 PMCID: PMC8372547 DOI: 10.1039/d1sc02407h] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 07/01/2021] [Indexed: 11/21/2022] Open
Abstract
Control of charge carriers that transport through the molecular junctions is essential for thermoelectric materials. In general, the charge carrier depends on the dominant conduction orbitals and is dominantly determined by the terminal anchor groups. The present study discloses the synthesis, physical properties in solution, and single-molecule conductance of paddle-wheel diruthenium complexes 1R having diarylformamidinato supporting ligands (DArF: p-R-C6H4-NCHN-C6H4-R-p) and two axial thioanisylethynyl conducting anchor groups, revealing unique substituent effects with respect to the conduction orbitals. The complexes 1R with a few different aryl substituents (R = OMe, H, Cl, and CF3) were fully characterized by spectroscopic and crystallographic analyses. The single-molecule conductance determined by the scanning tunneling microscope break junction (STM-BJ) technique was in the 10-5 to 10-4 G 0 region, and the order of conductance was 1OMe > 1CF3 ≫ 1H ∼ 1Cl, which was not consistent with the Hammett substituent constants σ of R. Cyclic voltammetry revealed the narrow HOMO-LUMO gaps of 1R originating from the diruthenium motif, as further supported by the DFT study. The DFT-NEGF analysis of this unique result revealed that the dominant conductance routes changed from HOMO conductance (for 1OMe) to LUMO conductance (for 1CF3). The drastic change in the conductance properties originates from the intrinsic narrow HOMO-LUMO gaps.
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Affiliation(s)
- Shiori Ogawa
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta, Midori-ku 226-8503 Yokohama Japan
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology Tokyo Institute of Technology 4259 Nagatsuta, Midori-ku 226-8503 Yokohama Japan
| | | | - Yuya Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta, Midori-ku 226-8503 Yokohama Japan
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology Tokyo Institute of Technology 4259 Nagatsuta, Midori-ku 226-8503 Yokohama Japan
| | - Tatsuhiko Ohto
- Graduate School of Engineering Science, Osaka University 1-3 Machikaneyama, Toyonaka Osaka 560-8531 Japan
| | - Tomofumi Tada
- Kyushu University Platform of Inter/Transdisciplinary Energy Research, Research Facilities for Co-Evolutional Social Systems, Kyushu University 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
| | - Hirokazu Tada
- Graduate School of Engineering Science, Osaka University 1-3 Machikaneyama, Toyonaka Osaka 560-8531 Japan
| | - Shintaro Fujii
- Department of Chemistry, School of Science, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku 152-8551 Tokyo Japan
| | - Tomoaki Nishino
- Department of Chemistry, School of Science, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku 152-8551 Tokyo Japan
| | - Munetaka Akita
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta, Midori-ku 226-8503 Yokohama Japan
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology Tokyo Institute of Technology 4259 Nagatsuta, Midori-ku 226-8503 Yokohama Japan
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8
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Van Caemelbecke E, Phan T, Osterloh WR, Kadish KM. Electrochemistry of metal-metal bonded diruthenium complexes. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2020.213706] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Wang H, Shao JY, Duan R, Wang KZ, Zhong YW. Synthesis and electronic coupling studies of cyclometalated diruthenium complexes bridged by 3,3',5,5'-tetrakis(benzimidazol-2-yl)-biphenyl. Dalton Trans 2021; 50:4219-4230. [PMID: 33687405 DOI: 10.1039/d1dt00263e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Three cyclometalated diruthenium complexes bridged by 3,3',5,5'-tetrakis(benzimidazol-2-yl)biphenyl (H-tbibp) and capped with different terminal ligands have been synthesized and examined. In addition, two monoruthenium complexes with H-tbibp have been prepared for the purpose of comparison studies. The degree of Ru-Ru electronic coupling of these diruthenium complexes has been investigated by electrochemical and intervalence charge-transfer (IVCT) analyses. These results suggest that when the same or similar terminal ligands are used, the strength of H-tbibp in mediating the Ru-Ru coupling is enhanced with respect to that of the previously reported bridging ligand 3,3',5,5'-tetrakis(N-methylbenzimidazol-2-yl)biphenyl, but it is slightly inferior to that of the classical bridging ligand 3,3',5,5'-tetrakis(pyrid-2-yl)biphenyl. This trend is also supported by CNS analyses based on the hole-superexchange mechanism. In addition, DFT calculations have been performed to probe the spin density distributions of the singly-oxidized diruthenium complexes with H-tbibp and TDDFT calculations are used to reproduce the IVCT transitions.
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Affiliation(s)
- Hao Wang
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, China.
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10
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Raghavan A, Yuan F, Ren T. Drastic Tuning of the Electronic Structures of Diruthenium Aryl Complexes by Isoelectronic Axial Ligands. Inorg Chem 2020; 59:8663-8666. [PMID: 32568533 DOI: 10.1021/acs.inorgchem.0c01755] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reported herein is the use of aryls as axial ligands to manipulate reactivity at the distal metal site through metal-metal-ligand interactions in diruthenium paddlewheel complexes. The vacant ruthenium site in Ru2(ap)4(Ar) (1; ap = 2-anilinopyridinate and Ar = C6H4-4-NMe2), thus rendered reactive, is able to bind a series of isoelectronic ligands to afford three complexes of the form (Y)[Ru2(ap)4](Ar) [Y = CN- (2), HC≡C- (3), CO (4)], each of which exhibits a distinct electronic structure. While reactions with anionic ligands subsequently result in oxidation of the diruthenium core from Ru2(II,III) to Ru2(III,III), the reaction with CO yields a rare example of a Ru2(II,III)-COaxial adduct. The latter reaction is particularly interesting in its completely reversible change of the ground state from S = 3/2 in 1 to S = 1/2 in 4, the first of its kind seen in Ru2(II,III) species. In general, this work sheds light on the modulation of the electronic structure of diruthenium paddlewheel complexes using distinct coordination environments around each of the ruthenium centers.
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Affiliation(s)
- Adharsh Raghavan
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Fang Yuan
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tong Ren
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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11
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Coloma I, Cortijo M, Fernández-Sánchez I, Perles J, Priego JL, Gutiérrez C, Jiménez-Aparicio R, Desvoyes B, Herrero S. pH- and Time-Dependent Release of Phytohormones from Diruthenium Complexes. Inorg Chem 2020; 59:7779-7788. [PMID: 32412249 DOI: 10.1021/acs.inorgchem.0c00844] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The controlled release of functionally active compounds is important in a variety of applications. Here, we have synthesized, characterized, and studied the magnetic properties of three novel metal-metal-bonded tris(formamidinato) Ru25+ complexes. We have used different auxin-related hormones, indole-3-acetate (IAA), 2,4-dichlorophenoxyacetate (2,4-D), and 1-naphthaleneacetate (NAA), to generate [Ru2Cl(μ-DPhF)3(μ-IAA)] (RuIAA), [Ru2Cl(μ-DPhF)3(μ-2,4-D)] (Ru2,4-D), and [Ru2Cl(μ-DPhF)3(μ-NAA)] (RuNAA) (DPhF = N,N'-diphenylformamidinate). The crystal structures of RuIAA, RuIAA·THF, Ru2,4-D·CH2Cl2, and RuNAA·0.5THF have been determined by single-crystal X-ray diffraction. To assess the releasing capacity of the bound hormone, we have employed a biological assay that relied on Arabidopsis thaliana plants expressing an auxin reporter gene and we demonstrate that the release of the phytohormones from RuIAA, Ru2,4-D, and RuNAA is pH- and time-dependent. These studies serve as a proof of concept showing the potential of these types of compounds as biological molecule carriers.
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Affiliation(s)
- Isabel Coloma
- Departamento de Quı́mica Inorgánica, Facultad de Ciencias Quı́micas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, Spain
| | - Miguel Cortijo
- Departamento de Quı́mica Inorgánica, Facultad de Ciencias Quı́micas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, Spain
| | - Inés Fernández-Sánchez
- Departamento de Quı́mica Inorgánica, Facultad de Ciencias Quı́micas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, Spain
| | - Josefina Perles
- Laboratorio de Difracción de Rayos X de Monocristal, Servicio Interdepartamental de Investigación, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - José L Priego
- Departamento de Quı́mica Inorgánica, Facultad de Ciencias Quı́micas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, Spain
| | - Crisanto Gutiérrez
- Centro de Biologı́a Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, E-28049 Madrid, Spain
| | - Reyes Jiménez-Aparicio
- Departamento de Quı́mica Inorgánica, Facultad de Ciencias Quı́micas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, Spain
| | - Bénédicte Desvoyes
- Centro de Biologı́a Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, E-28049 Madrid, Spain
| | - Santiago Herrero
- Departamento de Quı́mica Inorgánica, Facultad de Ciencias Quı́micas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, Spain
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Millet A, Xue C, Song E, Turro C, Dunbar KR. Synthetic Strategies for Trapping the Elusive trans-Dirhodium(II,II) Formamidinate Isomer: Effects of Cis versus Trans Geometry on the Photophysical Properties. Inorg Chem 2020; 59:2255-2265. [PMID: 31999106 DOI: 10.1021/acs.inorgchem.9b02966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cis- and trans-dirhodium(II,II) complexes cis-[Rh2(μ-DTolF)2(μ-np)(MeCN)4][BF4]2 (1; DTolF = N,N'-di-p-tolylformamidinate and np = 1,8-naphthyridine), cis- and trans-[Rh2(μ-DTolF)2(μ-qxnp)(MeCN)3][BF4]2 [2 and 3, respectively, where qxnp = 2-(1,8-naphthyridin-2-yl)quinoxaline], and trans-[Rh2(μ-DTolF)2(μ-qxnp)2][BF4]2 (4) were synthesized and characterized. A new synthetic methodology was developed that consists of the sequential addition of π-accepting axially blocking ligands to favor formation of the first example of a bis-substituted formamidinate-bearing trans product. Isolation of the intermediates 2 and 3 provides insight into the mechanistic requirements for obtaining 4 and the cis analogue, cis-[Rh2(μ-DTolF)2(μ-qxnp)2][BF4]2 (5). Density functional theory calculations provide support for the synthetic mechanism and proposed intermediates. The metal/ligand-to-ligand charge-transfer (ML-LCT) absorption maximum of the trans complex 4 at 832 nm is red-shifted by 1173 cm-1 and exhibits shorter lifetimes of the 1ML-LCT and 3ML-LCT excited states, 3 ps and 0.40 ns, respectively, compared to those of the cis analogue 5. The shorter excited-state lifetimes of 4 are attributed to the longer Rh-Rh bond of 2.4942(8) Å relative to that in 5, 2.4498(2) Å. A longer metal-metal bond reflects a decreased overlap of the Rh atoms, which leads to more accessible metal-centered excited states for radiationless deactivation. The 3ML-LCT excited states of 4 and 5 undergo reversible bimolecular charge transfer with the electron donor p-phenylenediamine when irradiated with low-energy light. These results indicate that trans isomers are a source of unexplored tunability for potential p-type semiconductor applications and, given their distinct geometric arrangement, constitute useful building blocks for supramolecular architectures with potentially interesting photophysical properties.
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Affiliation(s)
- Agustin Millet
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
| | - Congcong Xue
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Ellen Song
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
| | - Claudia Turro
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Kim R Dunbar
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
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