1
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Haaf S, Engels E, Kaifer E, Himmel HJ. Hexaguanidino-Triptycenes and Triphenylenes: Electronic Coupling in Molecules Containing Three Redox-Active o-Diguanidinobenzene Units Connected either Directly or Interacting Through Homoconjugation. Chemistry 2024; 30:e202301903. [PMID: 37815019 DOI: 10.1002/chem.202301903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 09/22/2023] [Accepted: 10/10/2023] [Indexed: 10/11/2023]
Abstract
Novel redox-active hexaguanidine molecules with multiple redox states were synthesized by connecting three o-diguanidinobenzene units. In 2,3,6,7,14,15-hexaguanidino-triptycenes, the three redox-active o-diguanidinobenzene units are connected through C-C bonds to the sp3 -hybridized bridgehead C atoms, and in 2,3,6,7,10,11-hexaguanidino-triphenylenes they are directly connected. The connectivity difference leads to different electronic coupling between the three redox-active o-diguanidinobenzene units, with homoconjugation being present in the triptycene, but not in the triphenylene compounds. Motivated by the appearance of an intense low-energy electronic transition, we especially analysed the effect of homoconjugation on the electronic structure and charge delocalization in the dicationic redox state of the triptycene derivatives. Then, several trinuclear high-spin cobalt (and copper) complexes were synthesized with the triphenylene and triptycene ligands, and the magnetic coupling and redox properties analysed. By choice of the coligands (hexafluoroacetylacetonate, trifluoroacetylacetonate and acetylacetonate), oxidation could be switched between metal- and ligand-centered redox events, leading to drastic changes in the magnetic or optical properties, especially as a consequence of homoconjugation in the triptycene derivatives.
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Affiliation(s)
- Sebastian Haaf
- Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Eliane Engels
- Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Elisabeth Kaifer
- Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hans-Jörg Himmel
- Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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2
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Redox-active ligands for chemical, electrochemical, and photochemical molecular conversions. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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3
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Lohmeyer L, Werr M, Kaifer E, Himmel H. Interplay and Competition Between Two Different Types of Redox-Active Ligands in Cobalt Complexes: How to Allocate the Electrons? Chemistry 2022; 28:e202201789. [PMID: 35894809 PMCID: PMC9804828 DOI: 10.1002/chem.202201789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Indexed: 01/09/2023]
Abstract
The field of molecular transition metal complexes with redox-active ligands is dominated by compounds with one or two units of the same redox-active ligand; complexes in which different redox-active ligands are bound to the same metal are uncommon. This work reports the first molecular coordination compounds in which redox-active bisguanidine or urea azine (biguanidine) ligands as well as oxolene ligands are bound to the same cobalt atom. The combination of two different redox-active ligands leads to mono- as well as unprecedented dinuclear cobalt complexes, being multiple (four or six) center redox systems with intriguing electronic structures, all exhibiting radical ligands. By changing the redox potential of the ligands through derivatisation, the electronic structure of the complexes could be altered in a rational way.
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Affiliation(s)
- Lukas Lohmeyer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Marco Werr
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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4
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Turro RF, Brandstätter M, Reisman SE. Nickel-Catalyzed Reductive Alkylation of Heteroaryl Imines. Angew Chem Int Ed Engl 2022; 61:e202207597. [PMID: 35791274 PMCID: PMC9474666 DOI: 10.1002/anie.202207597] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Indexed: 09/20/2023]
Abstract
The preparation of heterobenzylic amines by a Ni-catalyzed reductive cross-coupling between heteroaryl imines and C(sp3 ) electrophiles is reported. This umpolung-type alkylation proceeds under mild conditions, avoids the pre-generation of organometallic reagents, and exhibits good functional group tolerance. Mechanistic studies are consistent with the imine substrate acting as a redox-active ligand upon coordination to a low-valent Ni center. The resulting bis(2-imino)heterocycle⋅Ni complexes can engage in alkylation reactions with a variety of C(sp3 ) electrophiles, giving heterobenzylic amine products in good yields.
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Affiliation(s)
- Raymond F Turro
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Marco Brandstätter
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Sarah E Reisman
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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5
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Turro RF, Brandstätter M, Reisman SE. Nickel‐Catalyzed Reductive Alkylation of Heteroaryl Imines. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Raymond F. Turro
- California Institute of Technology Chemistry & Chemical Engineering UNITED STATES
| | - Marco Brandstätter
- California Institute of Technology Chemistry & Chemical Engineering UNITED STATES
| | - Sarah E. Reisman
- California Institute of Technology Divisional Chemistry and Chemical Enineering 1200 E California BoulevardMail Code 101-20 91125 Pasadena UNITED STATES
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6
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Mukhopadhyay N, Sengupta A, Vijay AK, Lloret F, Mukherjee R. Ni(II) complexes of a new tetradentate NN'N''O picolinoyl-1,2-phenylenediamide-phenolate redox-active ligand at different redox levels. Dalton Trans 2022; 51:9017-9029. [PMID: 35638812 DOI: 10.1039/d2dt01043g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Three square planar nickel(II) complexes of a new asymmetric tetradentate redox-active ligand H3L2 in its deprotonated form, at three redox levels, open-shell semiquinonate(1-) π radical, quinone(0) and closed-shell dianion of its 2-aminophenolate part, have been synthesized. The coordinated ligand provides N (pyridine) and N' and N'' (carboxamide and 1,2-phenylenediamide, respectively) and O (phenolate) donor sites. Cyclic voltammetry on the parent complex [Ni(L2)] 1 in CH2Cl2 established a three-membered electron-transfer series (oxidative response at E1/2 = 0.57 V and reductive response at -0.32 V vs. SCE) consisting of neutral, monocationic and monoanionic [Ni(L2)]z (z = 0, 1+ and 1-). Oxidation of 1 with AgSbF6 affords [Ni(L2)](SbF6) (2) and reduction of 1 with cobaltocene yields [Co(η5-C5H5)2][Ni(L2)] (3). The molecular structures of 1·CH3CN, 2·0.5CH2Cl2 and 3·C6H6 have been determined by X-ray crystallography at 100 K. Characterization by 1H NMR, X-band EPR (gav = 2.006 (solid); 2.008 (CH2Cl2-C6H5CH3 glass); 80 K) and UV-VIS-NIR spectral properties established that 1, 2 and 3 have [NiII{(L2)˙2-}], [NiII{(L2)-}]+/1+ and [NiII{(L2)3-}]-/1- electronic states, respectively. Thus, the redox processes are ligand-centred. While 1 possesses paramagnetic St (total spin) = 1/2, 2 and 3 possess diamagnetic ground-state St = 0. Interestingly, the variable-temperature (2-300 K) magnetic measurement reveals that 1 with the St = 1/2 ground state attains the antiferromagnetic St = 0 state at a very low temperature, due to weak noncovalent interactions via π-π stacking. Density functional theory (DFT) electronic structural calculations at the B3LYP level of theory rationalized the experimental results. In the UV-VIS-NIR spectra, broad absorptions are recorded for 1 and 2 in the range of 800-1600 nm; however, such an absorption is absent for 3. Time-dependent (TD)-DFT calculations provide a very good fit with the experimental spectra and allow us to identify the observed electronic transitions.
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Affiliation(s)
- Narottam Mukhopadhyay
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741 246, India
| | - Arunava Sengupta
- Department of Chemistry, Techno India University, West Bengal, Kolkata 700091, India
| | - Aswin Kottapurath Vijay
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741 246, India
| | - Francesc Lloret
- Departament de Química Inorgànica/Instituto de Ciencia Molecular (ICMOL), Universitat de València, Polígono de la Coma, s/n, 46980 Paterna, València, Spain
| | - Rabindranath Mukherjee
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India.
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Pashanova KI, Poddel'sky AI, Piskunov AV. Complexes of “late” transition metals of the 3d row based on functionalized o-iminobenzoquinone type ligands: Interrelation of molecular and electronic structure, magnetic behaviour. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214399] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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8
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Ali A, Bhowmik S, Barman SK, Mukhopadhyay N, Glüer Nee Schiewer CE, Lloret F, Meyer F, Mukherjee R. Iron(III) Complexes of a Hexadentate Thioether-Appended 2-Aminophenol Ligand: Redox-Driven Spin State Switchover. Inorg Chem 2022; 61:5292-5308. [PMID: 35312298 DOI: 10.1021/acs.inorgchem.1c03992] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A green complex [Fe(L3)] (1), supported by the deprotonated form of a hexadentate noninnocent redox-active thioether-appended 2-aminophenolate ligand (H4L3 = N,N'-bis(2-hydroxy-3,5-di-tert-butylphenyl)-2,2'-diamino(diphenyldithio)ethane), has been synthesized and structurally characterized at 100(2) K and 298(2) K. In CH2Cl2, 1 displays two oxidative and a reductive one-electron redox processes at E1/2 values of -0.52 and 0.20 V, and -0.85 V versus the Fc+/Fc redox couple, respectively. The one-electron oxidized 1+ and one-electron reduced 1- forms, isolated as a blackish-blue solid 1(PF6)·CH2Cl2 (2) and a gray solid [Co(η5-C5H5)2]1·DMF (3), have been structurally characterized at 100(2) K. Structural parameters at 100 K of the ligand backbone and metrical oxidation state values unambiguously establish the electronic states as [FeIII{(LAPO,N)2-}{(LISQO,N)•-}{(LS,S)0}] (1) (two tridentate halves are electronically asymmetric-ligand mixed-valency), [FeIII{(LISQO,N)•-}{(LISQO,N)•-}{(LS,S)0}]+ (1+), and [FeIII{(LAPO,N)2-}{(LAPO,N)2-}{(LS,S)0}]- (1-) [dianionic 2-amidophenolate(2-) (LAPO,N)2- and monoanionic 2-iminobenzosemiquinonate(1-) π-radical (Srad = 1/2) (LISQ)•- redox level]. Mössbauer spectral data of 1 at 295, 200, and 80 K reveal that it has a major low-spin (ls)-Fe(III) and a minor ls-Fe(II) component (redox isomers), and at 7 K, the major component exists exclusively. Thus, in 1, the occurrence of a thermally driven valence-tautomeric (VT) equilibrium (asymmetric) [FeIII{(LAPO,N)2-}{(LISQO,N)•-}{(LS,S)0}] ⇌ (symmetric) [FeII{(LISQO,N)•-}{(LISQO,N)•-}{(LS,S)0}] (80-295 K) is implicated. Mössbauer spectral parameters unequivocally establish that 1+ is a ls-Fe(III) complex. In contrast, the monoanion 1- contains a high-spin (hs)-Fe(III) center (SFe = 5/2), as is deduced from its Mössbauer and EPR spectra. Complexes 1-3 possess total spin ground states St = 0, 1/2, and 5/2, respectively, based on 1H NMR and EPR spectra, the variable-temperature (2-300 K) magnetic behavior of 2, and the μeff value of 3 at 300 K. Broken-symmetry density functional theory (DFT) calculations at the B3LYP-level of theory reveal that the unpaired electron in 1+/2 is due to the (LISQ)•- redox level [ls-Fe(III) (SFe = 1/2) is strongly antiferromagnetically coupled to one of the (LISQ)•- radicals (Srad = 1/2)], and 1-/3 is a hs-Fe(III) complex, supported by (L3)4- with two-halves in the (LAP)2- redox level. Complex 1 can have either a symmetric or asymmetric electronic state. As per DFT calculation, the former state is stabilized by -3.9 kcal/mol over the latter (DFT usually stabilizes electronically symmetric structure). Time-dependent (TD)-DFT calculations shed light on the origin of observed UV-vis-NIR spectral absorptions for 1-3 and corroborate the results of spectroelectrochemical experiments (300-1100 nm) on 1 (CH2Cl2; 298 K). Variable-temperature (218-298 K; CH2Cl2) absorption spectral (400-1000 nm) studies on 1 justify the presence of VT equilibrium in the solution-state.
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Affiliation(s)
- Akram Ali
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Saumitra Bhowmik
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741246, India
| | - Suman K Barman
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Narottam Mukhopadhyay
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741246, India
| | | | - Francesc Lloret
- Departament de Quımíca, Inorgànica/Instituto de Ciencia Molecular (ICMOL), Universitat de Valeńcia, Polígono de la Coma, s/n, Paterna, València 46980, Spain
| | - Franc Meyer
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
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9
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Mondal R, Guin AK, Chakraborty G, Paul ND. Metal-ligand cooperative approaches in homogeneous catalysis using transition metal complex catalysts of redox noninnocent ligands. Org Biomol Chem 2022; 20:296-328. [PMID: 34904619 DOI: 10.1039/d1ob01153g] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Catalysis offers a straightforward route to prepare various value-added molecules starting from readily available raw materials. The catalytic reactions mostly involve multi-electron transformations. Hence, compared to the inexpensive and readily available 3d-metals, the 4d and 5d-transition metals get an extra advantage for performing multi-electron catalytic reactions as the heavier transition metals prefer two-electron redox events. However, for sustainable development, these expensive and scarce heavy metal-based catalysts need to be replaced by inexpensive, environmentally benign, and economically affordable 3d-metal catalysts. In this regard, a metal-ligand cooperative approach involving transition metal complexes of redox noninnocent ligands offers an attractive alternative. The synergistic participation of redox-active ligands during electron transfer events allows multi-electron transformations using 3d-metal catalysts and allows interesting chemical transformations using 4d and 5d-metals as well. Herein we summarize an up-to-date literature report on the metal-ligand cooperative approaches using transition metal complexes of redox noninnocent ligands as catalysts for a few selected types of catalytic reactions.
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Affiliation(s)
- Rakesh Mondal
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur Botanic Garden, Howrah 711103, India.
| | - Amit Kumar Guin
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur Botanic Garden, Howrah 711103, India.
| | - Gargi Chakraborty
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur Botanic Garden, Howrah 711103, India.
| | - Nanda D Paul
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur Botanic Garden, Howrah 711103, India.
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10
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Role of a Redox-Active Ligand Close to a Dinuclear Activating Framework. TOP ORGANOMETAL CHEM 2022. [DOI: 10.1007/3418_2022_77] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Switchover from NiIIN2O2 to NiIIN2O2S2 coordination triggered by the redox behaviour of a non-innocent 2-aminophenolate ligand. J CHEM SCI 2021. [DOI: 10.1007/s12039-021-01961-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Werr M, Kaifer E, Enders M, Asyuda A, Zharnikov M, Himmel H. Synthese eines Kupfer(I)‐Komplexes mit zwei ungepaarten Elektronen durch Oxidation eines Kupfer(II)‐Komplexes mit zwei redoxaktiven Liganden. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Marco Werr
- Anorganisch-Chemisches Institut Ruprecht-Karls Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut Ruprecht-Karls Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Markus Enders
- Anorganisch-Chemisches Institut Ruprecht-Karls Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Andika Asyuda
- Angewandte Physikalische Chemie Ruprecht-Karls Universität Heidelberg Im Neuenheimer Feld 253 69120 Heidelberg Deutschland
| | - Michael Zharnikov
- Angewandte Physikalische Chemie Ruprecht-Karls Universität Heidelberg Im Neuenheimer Feld 253 69120 Heidelberg Deutschland
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches Institut Ruprecht-Karls Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
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13
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Werr M, Kaifer E, Enders M, Asyuda A, Zharnikov M, Himmel H. A Copper(I) Complex with Two Unpaired Electrons, Synthesised by Oxidation of a Copper(II) Complex with Two Redox-Active Ligands. Angew Chem Int Ed Engl 2021; 60:23451-23462. [PMID: 34423532 PMCID: PMC8596453 DOI: 10.1002/anie.202109367] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 07/30/2021] [Indexed: 01/10/2023]
Abstract
Two homoleptic copper(II) complexes [Cu(L1)2 ] and [Cu(L2)2 ] with anionic redox-active ligands were synthesised, one with urea azine (L1) and the other with thio-urea azine (L2) ligands. One-electron oxidation of the complexes initiates an unprecedented redox-induced electron transfer process, leading to monocationic copper(I) complexes [Cu(L1)2 ]+ and [Cu(L2)2 ]+ with two oxidised ligands. While [Cu(L1)2 ]+ is best described as a CuI complex with two neutral radical ligands that couple antiferromagnetically, [Cu(L2)2 ]+ is a CuI complex with two clearly different ligand units in the solid state and with a magnetic susceptibility close to a diamagnetic compound. Further one-electron oxidation of the complex with L1 ligands results in a dication [Cu(L1)2 ]2+ , best described as a CuI complex with a twofold oxidised, monocationic ligand and a neutral radical ligand. The stability in at least three redox states, the accumulation of spin density at the ligands and the facile ligand-metal electron transfer make these complexes highly attractive for a variety of applications; here the catalytic aerobic oxidation of alcohols to aldehydes is tested.
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Affiliation(s)
- Marco Werr
- Anorganisch-Chemisches InstitutRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches InstitutRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Markus Enders
- Anorganisch-Chemisches InstitutRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Andika Asyuda
- Angewandte Physikalische ChemieRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 25369120HeidelbergGermany
| | - Michael Zharnikov
- Angewandte Physikalische ChemieRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 25369120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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Hanft A, Rottschäfer D, Wieprecht N, Geist F, Radacki K, Lichtenberg C. Aminotroponiminates: Impact of the NO 2 Functional Group on Coordination, Isomerisation, and Backbone Substitution. Chemistry 2021; 27:14250-14262. [PMID: 34314083 PMCID: PMC8597084 DOI: 10.1002/chem.202102324] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Indexed: 01/17/2023]
Abstract
Aminotroponiminate (ATI) ligands are a versatile class of redox-active and potentially cooperative ligands with a rich coordination chemistry that have consequently found a wide range of applications in synthesis and catalysis. While backbone substitution of these ligands has been investigated in some detail, the impact of electron-withdrawing groups on the coordination chemistry and reactivity of ATIs has been little investigated. We report here Li, Na, and K salts of an ATI ligand with a nitro-substituent in the backbone. It is demonstrated that the NO2 group actively contributes to the coordination chemistry of these complexes, effectively competing with the N,N-binding pocket as a coordination site. This results in an unprecedented E/Z isomerisation of an ATI imino group and culminates in the isolation of the first "naked" (i. e., without directional bonding to a metal atom) ATI anion. Reactions of sodium ATIs with silver(I) and tritylium salts gave the first N,N-coordinated silver ATI complexes and unprecedented backbone substitution reactions. Analytical techniques applied in this work include multinuclear (VT-)NMR spectroscopy, single-crystal X-ray diffraction analysis, and DFT calculations.
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Affiliation(s)
- Anna Hanft
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Dennis Rottschäfer
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Nele Wieprecht
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Felix Geist
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Krzysztof Radacki
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Crispin Lichtenberg
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
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Steuer L, Kaifer E, Himmel HJ. On the metal-ligand bonding in dinuclear complexes with redox-active guanidine ligands. Dalton Trans 2021; 50:9467-9482. [PMID: 34136887 DOI: 10.1039/d1dt01354h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Coordination compounds with redox-active ligands are currently intensively studied. Within this research theme, redox-active guanidines have been established as a new, eminent class of redox-active ligands. In this work the variation of metal-guanidine bonding in dinuclear transition metal complexes with bridging redox-active tetrakisguanidine ligands is analysed. A series of dinuclear complexes with different metals (Mn, Fe, Co, Ni, Cu and Zn) is synthesized, using either newly prepared redox-active tetrakisguanidino-dioxine or previously reported tetrakisguanidino-benzene ligands. The discussion of the bond properties in this work is predominantly based on the trends of structural parameters, derived from determination of single-crystal structures by X-ray diffraction and quantum chemical calculations. In addition, the trends in the redox potentials and magnetometric (SQUID) measurements on some of the complexes are included. Due to their combined σ- and π-electron donor capability, redox-active guanidine ligands are weak-field ligands; the σ- and π-bonding contributions vary with the metal. The results highlight the peculiarity of copper-guanidine bonding with a high π-bond contribution to metal-guanidine bonding, enabled by structural distortion of the coordination mode from tetrahedral in the direction of square-planar, short copper-guanidine bonds and minor displacement of the copper atoms from the ligand aromatic plane.
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Affiliation(s)
- Lena Steuer
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
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Lohmeyer L, Kaifer E, Enders M, Himmel H. Switching from Metal- to Ligand-Based Oxidation in Cobalt Complexes with Redox-Active Bisguanidine Ligands. Chemistry 2021; 27:11852-11867. [PMID: 34101917 PMCID: PMC8457109 DOI: 10.1002/chem.202101364] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Indexed: 11/19/2022]
Abstract
The control of the redox reactivity, magnetic and optical properties of the different redox states of complexes with redox‐active ligands permits their rational use in catalysis and materials science. The redox‐chemistry of octahedrally coordinated high‐spin CoII complexes (three unpaired electrons) with one redox‐active bisguanidine ligand and two acetylacetonato (acac) co‐ligands is completely changed by replacing the acac by hexafluoro‐acetylacetonato (hfacac) co‐ligands. The first one‐electron oxidation is metal‐centered in the case of the complexes with acac co‐ligands, giving diamagnetic CoIII complexes. By contrast, in the case of the less Lewis‐basic hfacac co‐ligands, the first one‐electron oxidation becomes ligand‐centered, leading to high‐spin CoII complexes with a radical monocationic guanidine ligand unit (four unpaired electrons). Ferromagnetic coupling between the spins on the metal and the organic radical in solution is evidenced by temperature‐dependent paramagnetic NMR studies, allowing to estimate the isotropic exchange coupling constant in solution. Second one‐electron oxidation leads to high‐spin CoII complexes with dicationic guanidine ligand units (three unpaired electrons) in the presence of hfacac co‐ligands, but to low‐spin CoIII complexes with radical monocationic, peralkylated guanidine ligand (one unpaired electron) in the presence of acac co‐ligands. The analysis of the electronic structures is complemented by quantum‐chemical calculations on the spin density distributions and relative energies of the possible redox isomers.
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Affiliation(s)
- Lukas Lohmeyer
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Markus Enders
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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17
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Jesse KA, Chang M, Filatov AS, Anderson JS. Iron(II) Complexes Featuring a Redox‐Active Dihydrazonopyrrole Ligand. Z Anorg Allg Chem 2021; 647:1415-1420. [DOI: 10.1002/zaac.202100097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Kate A. Jesse
- University of Chicago Department of Chemistry 929 E 57th St. Chicago IL 60637
| | - Mu‐Chieh Chang
- National Taiwan University Department of Chemistry No. 1, Section 4, Roosevelt Rd, Da'an District Taipei City Taiwan 10
| | | | - John S. Anderson
- University of Chicago Department of Chemistry 929 E 57th St. Chicago IL 60637
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18
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Liang Q, DeMuth JC, Radović A, Wolford NJ, Neidig ML, Song D. [2Fe-2S] Cluster Supported by Redox-Active o-Phenylenediamide Ligands and Its Application toward Dinitrogen Reduction. Inorg Chem 2021; 60:13811-13820. [PMID: 34043353 DOI: 10.1021/acs.inorgchem.1c00683] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
As prevalent cofactors in living organisms, iron-sulfur clusters participate in not only the electron-transfer processes but also the biosynthesis of other cofactors. Many synthetic iron-sulfur clusters have been used in model studies, aiming to mimic their biological functions and to gain mechanistic insight into the related biological systems. The smallest [2Fe-2S] clusters are typically used for one-electron processes because of their limited capacity. Our group is interested in functionalizing small iron-sulfur clusters with redox-active ligands to enhance their electron storage capacity, because such functionalized clusters can potentially mediate multielectron chemical transformations. Herein we report the synthesis, structural characterization, and catalytic activity of a diferric [2Fe-2S] cluster functionalized with two o-phenylenediamide ligands. The electrochemical and chemical reductions of such a cluster revealed rich redox chemistry. The functionalized diferric cluster can store up to four electrons reversibly, where the first two reduction events are ligand-based and the remainder metal-based. The diferric [2Fe-2S] cluster displays catalytic activity toward silylation of dinitrogen, affording up to 88 equiv of the amine product per iron center.
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Affiliation(s)
- Qiuming Liang
- Davenport Chemical Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Joshua C DeMuth
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Aleksa Radović
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Nikki J Wolford
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Michael L Neidig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Datong Song
- Davenport Chemical Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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19
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Lohmeyer L, Schön F, Kaifer E, Himmel H. Stimulierung eines redoxinduzierten Elektronentransfers durch Interligand‐Wasserstoffbrücken in einem Cobaltkomplex mit redoxaktivem Guanidin‐Liganden. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101423] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Lukas Lohmeyer
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Florian Schön
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
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20
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Lohmeyer L, Schön F, Kaifer E, Himmel HJ. Stimulation of Redox-Induced Electron Transfer by Interligand Hydrogen Bonding in a Cobalt Complex with Redox-Active Guanidine Ligand. Angew Chem Int Ed Engl 2021; 60:10415-10422. [PMID: 33616266 PMCID: PMC8252010 DOI: 10.1002/anie.202101423] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Indexed: 12/27/2022]
Abstract
Octahedrally coordinated cobalt(II) complexes with a redox‐active bisguanidine ligand and acac co‐ligands were synthesized and their redox chemistry analysed in detail. The N−H functions in a bisguanidine ligand with partially alkylated guanidino groups form N−H⋅⋅⋅O hydrogen bonds with the acac co‐ligands, thereby massively influencing the redox chemistry. For all complexes, the first one‐electron oxidation is metal‐centred, leading to CoIII complexes with neutral bisguanidine ligand units. Further one‐electron oxidation is ligand‐centred in the case of Co–bisguanidine complexes with fully alkylated guanidino groups, giving CoIII complexes with radical monocationic bisguanidine ligands. On the other hand, the hydrogen‐bond strengthening upon oxidation of the Co–bisguanidine complex with partially alkylated guanidino groups initiates metal reduction (CoIII→CoII) and two‐electron oxidation of the guanidine ligand, providing the first example for the stimulation of redox‐induced electron transfer by interligand hydrogen bonding.
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Affiliation(s)
- Lukas Lohmeyer
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Florian Schön
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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21
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Rask AE, Zimmerman PM. Toward Full Configuration Interaction for Transition-Metal Complexes. J Phys Chem A 2021; 125:1598-1609. [DOI: 10.1021/acs.jpca.0c07624] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Alan E. Rask
- Department of Chemistry, University of Michigan, 930N. University Avenue, Ann Arbor 48109, Michigan, United States
| | - Paul M. Zimmerman
- Department of Chemistry, University of Michigan, 930N. University Avenue, Ann Arbor 48109, Michigan, United States
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22
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Haaf S, Kaifer E, Wadepohl H, Himmel H. Use of Crown Ether Functions as Secondary Coordination Spheres for the Manipulation of Ligand-Metal Intramolecular Electron Transfer in Copper-Guanidine Complexes. Chemistry 2021; 27:959-970. [PMID: 32833269 PMCID: PMC7839521 DOI: 10.1002/chem.202003469] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Indexed: 01/16/2023]
Abstract
Intramolecular electron transfer (IET) between a redox-active organic ligand and a metal in a complex is of fundamental interest and used in a variety of applications. In this work it is demonstrated that secondary coordination sphere motifs can be applied to trigger a radical change in the electronic structure of copper complexes with a redox-active guanidine ligand through ligand-metal IET. Hence, crown ether functions attached to the ligand allow the manipulation of the degree of IET between the guanidine ligand and the copper atom through metal encapsulation.
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Affiliation(s)
- Sebastian Haaf
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hubert Wadepohl
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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23
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Garhwal S, Kroeger AA, Thenarukandiyil R, Fridman N, Karton A, de Ruiter G. Manganese-Catalyzed Hydroboration of Terminal Olefins and Metal-Dependent Selectivity in Internal Olefin Isomerization-Hydroboration. Inorg Chem 2021; 60:494-504. [PMID: 33325695 DOI: 10.1021/acs.inorgchem.0c03451] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the past decade, the use of earth-abundant metals in homogeneous catalysis has flourished. In particular, metals such as cobalt and iron have been used extensively in reductive transformations including hydrogenation, hydroboration, and hydrosilylation. Manganese, on the other hand, has been considerably less explored in these reductive transformations. Here, we report a well-defined manganese complex, [Mn(iPrBDI)(OTf)2] (2a; BDI = bipyridinediimine), that is an active precatalyst in the hydroboration of a variety of electronically differentiated alkenes (>20 examples). The hydroboration is specifically selective for terminal alkenes and occurs with exclusive anti-Markovnikov selectivity. In contrast, when using the analogous cobalt complex [Co(iPrBDI)(OTf)2] (3a), internal alkenes are hydroborated efficiently, where a sequence of isomerization steps ultimately leads to their hydroboration. The contrasting terminal versus internal alkene selectivity for manganese and cobalt was investigated computationally and is further discussed in the herein-reported study.
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Affiliation(s)
- Subhash Garhwal
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 3200008 Haifa, Israel
| | - Asja A Kroeger
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, 6009 Perth, WA Australia
| | - Ranjeesh Thenarukandiyil
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 3200008 Haifa, Israel
| | - Natalia Fridman
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 3200008 Haifa, Israel
| | - Amir Karton
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, 6009 Perth, WA Australia
| | - Graham de Ruiter
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 3200008 Haifa, Israel
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24
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Saha A, Rajput A, Gupta P, Mukherjee R. Probing the electronic structure of [Ru(L 1) 2] Z ( z = 0, 1+ and 2+) (H 2L 1: a tridentate 2-aminophenol derivative) complexes in three ligand redox levels. Dalton Trans 2020; 49:15355-15375. [PMID: 33135029 DOI: 10.1039/d0dt03074k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aerobic reaction between [RuII(DMSO)4Cl2], a redox-active 2-aminophenol-based ligand (H2L1: 2-[2-(benzylthio)phenylamino]-4,6-di-tert-butylphenol) and Et3N in MeOH under refluxing conditions afforded a purple complex [Ru(L1)2] (S = 0). Structural analysis reveals that the tridentate ligand coordinates in a mer conformation providing a distorted octahedral RuN2O2S2 coordination. Cyclic voltammetry on 1 in CH2Cl2 reveals the accessability of the monocation, dication and monoanion forms. Reddish purple monocation [Ru(L1)2](PF6)·CH2Cl2 ([1OX1](PF6)·CH2Cl2; S = 1/2) and green dication [Ru(L1)2](BF4)2·H2O ([1OX2](BF4)2·H2O; S = 0) have been isolated through the chemical oxidation of 1 in CH2Cl2 by [FeIII(η5-C5H5)2](PF6) and AgBF4, respectively. A structural analysis of the single crystals of the monocation and the dication with the compositions [1OX1](PF6)·CH2Cl2·H2O (2) and [1OX2](BF4)2·1.7H2O (3), respectively, has been done. Metrical (metal-ligand and ligand backbone) parameters, values of metrical oxidation states of coordinated ligands, 1H NMR spectra of 1 and [1OX2](BF4)2·H2O, EPR spectra of [1OX1](PF6)·CH2Cl2, X-ray photoelectron and UV-VIS-NIR spectra of 1-3, spin population analysis from broken-symmetry (BS) density functional theory (DFT) calculations and quasi-restricted orbital (QRO) analysis have allowed us to assign the electronic structure of the complexes. The complexes exhibit highly covalent metal-ligand interactions. The electronic states of 1, [1OX1]1+ and [1OX2]2+ are best described as [RuII{(LISQ)˙-}2] ↔ [RuIII{(LAP)2-}{(LISQ)˙-}] (S = 0), [RuIII{(LISQ)˙-}2]1+ (S = 1/2) and [RuII{(LIBQ)0}2]2+ ↔ [RuIII{(LISQ)˙-}{(LIBQ)0}]2+ (S = 0), respectively. Notably, all redox processes are ligand-centred. Absorption spectral properties have been rationalized based on time-dependent (TD)-DFT calculations. For 1, the appearance of an IVCT band at 1100 nm supports its Class II-III (borderline) ligand-based mixed-valence character.
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Affiliation(s)
- Anannya Saha
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741 246, India
| | - Amit Rajput
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India. and Department of Chemistry, School of Basic and Applied Sciences, G. D. Goenka University, Sohna Road, Gurugram 122 103, Haryana, India
| | - Puneet Gupta
- Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247 667, India
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25
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Mukherjee R. Assigning Ligand Redox Levels in Complexes of 2-Aminophenolates: Structural Signatures. Inorg Chem 2020; 59:12961-12977. [PMID: 32881491 DOI: 10.1021/acs.inorgchem.0c00240] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The purpose of this Viewpoint is to provide a broad-ranging update of advances in the coordination chemistry of redox-active (noninnocent) 2-aminophenolates, with emphasis on two ligand backbone structural parameters, the average of C-O and C-N (C-O/N) bond distances and Δa values, signifying the degree of bond-length alternation in the six-membered ring, in order to identify the redox level of the coordinated ligands. In the absence of magnetic, spectroscopic, and redox results, it has been established that it is possible to assign the electronic ground state of a coordination complex of 2-aminophenolates with consideration of charge, metal-ligand bond distances, and two very promising ligand backbone structural parameters. From a closer look at the sensitive ligand backbone metrical parameters of a diversified group of about 120 transition-metal complexes, a few very useful generalizations have been made.
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26
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Wagner C, Kreis F, Popp D, Hübner O, Kaifer E, Himmel H. 1,2,4,5-Tetrakis(tetramethylguanidino)-3,6-diethynyl-benzenes: Fluorescent Probes, Redox-Active Ligands and Strong Organic Electron Donors. Chemistry 2020; 26:10336-10347. [PMID: 32368816 PMCID: PMC7497081 DOI: 10.1002/chem.202001557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/30/2020] [Indexed: 11/25/2022]
Abstract
In this work, the change of reactivity induced by the introduction of two para-ethynyl substituents (CCSi(iPr)3 or CCH) to the organic electron-donor 1,2,4,5-tetrakis(tetramethylguanidino)-benzene is evaluated. The redox-properties and redox-state dependent fluorescence are evaluated, and dinuclear CuI and CuII complexes synthesized. The Lewis-acidic B(C6 F5 )3 substitutes the proton of the ethynyl -CCH groups to give new anionic -CCB(C6 F5 )3 - substituents, leading eventually to a novel dianionic strong electron donor in its diprotonated form. Its two-electron oxidation with dioxygen in the presence of a copper catalyst yields the first redox-active guanidine that is neutral (instead of cationic) in its oxidized form.
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Affiliation(s)
- Conrad Wagner
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Franka Kreis
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Dennis Popp
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Olaf Hübner
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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27
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Khan FF, Chowdhury AD, Lahiri GK. Bond Activations Assisted by Redox Active Ligand Scaffolds. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000005] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Farheen Fatima Khan
- Department of Chemistry; Indian Institute of Technology Bombay; Powai 400076 Mumbai India
| | | | - Goutam Kumar Lahiri
- Department of Chemistry; Indian Institute of Technology Bombay; Powai 400076 Mumbai India
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28
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Liang Q, Lin JH, DeMuth JC, Neidig ML, Song D. Syntheses and characterizations of iron complexes of bulky o-phenylenediamide ligand. Dalton Trans 2020; 49:12287-12297. [DOI: 10.1039/d0dt02087g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the reactivity of the iron complexes of a bulky phenylenediamide ligand.
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Affiliation(s)
- Qiuming Liang
- Davenport Chemical Research Laboratories
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
| | - Jack H. Lin
- Davenport Chemical Research Laboratories
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
| | | | | | - Datong Song
- Davenport Chemical Research Laboratories
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
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29
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Recent advances in the chemistry of group 9—Pincer organometallics. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2020. [DOI: 10.1016/bs.adomc.2019.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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30
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Piskunov AV, Tsys KV, Chegerev MG, Cherkasov AV. Tin(II) Complexes Based on N-Alkyl-Substituted o-Amidophenolate Ligands: Acid–Base and Redox Transformations. RUSS J COORD CHEM+ 2019. [DOI: 10.1134/s1070328419090069] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Spielvogel KD, Coughlin EJ, Petras H, Luna JA, Benson A, Donahue CM, Kibasa A, Lee K, Salacinski R, Bart SC, Shaw SK, Shepherd JJ, Daly SR. The Influence of Redox-Innocent Donor Groups in Tetradentate Ligands Derived from o-Phenylenediamine: Electronic Structure Investigations with Nickel. Inorg Chem 2019; 58:12756-12774. [DOI: 10.1021/acs.inorgchem.9b01675] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Kyle D. Spielvogel
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - Ezra J. Coughlin
- H.C. Brown Laboratory, Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Hayley Petras
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - Javier A. Luna
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - Austin Benson
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - Courtney M. Donahue
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - Amani Kibasa
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - Kyounghoon Lee
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - Ryan Salacinski
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - Suzanne C. Bart
- H.C. Brown Laboratory, Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Scott K. Shaw
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - James J. Shepherd
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
| | - Scott R. Daly
- Department of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242-1294, United States
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32
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Arevalo R, Chirik PJ. Enabling Two-Electron Pathways with Iron and Cobalt: From Ligand Design to Catalytic Applications. J Am Chem Soc 2019; 141:9106-9123. [PMID: 31084022 DOI: 10.1021/jacs.9b03337] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Homogeneous catalysis with Earth-abundant, first-row transition metals, including iron and cobalt, has gained considerable recent attention as a potentially cost-effective and sustainable alternative to more commonly and historically used precious metals. Because fundamental organometallic transformations, such as oxidative addition and reductive elimination, are two-electron processes and essential steps in many important catalytic cycles, controlling redox chemistry-in particular overcoming one-electron chemistry-has been as a central challenge with Earth-abundant metals. This Perspective focuses on approaches to impart sufficiently strong ligand fields to generate electron-rich metal complexes able to promote oxidative addition reactions where the redox changes are exclusively metal-based. Emphasis is placed on how ligand design and exploration of fundamental organometallic chemistry coupled with mechanistic understanding have been used to discover iron catalysts for the hydrogen isotope exchange in pharmaceuticals and cobalt catalysts for C(sp2)-H borylation reactions. A pervasive theme is that first-row metal complexes often promote unique chemistry from their precious-metal counterparts, demonstrating that these elements offer a host of new opportunities for reaction discovery and for more sustainable catalysis.
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Affiliation(s)
- Rebeca Arevalo
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Paul J Chirik
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
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33
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Piskunov AV, Pashanova KI, Bogomyakov AS, Smolyaninov IV, Starikov AG, Fukin GK. Cobalt complexes with hemilabile o-iminobenzoquinonate ligands: a novel example of redox-induced electron transfer. Dalton Trans 2018; 47:15049-15060. [PMID: 30303221 DOI: 10.1039/c8dt02733a] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The tetracoordinated square-planar CoIII complex (imSQC(O)Ph)CoIII(APC(O)Ph) (1) bearing a radical anion and the closed-shell o-amidophenolate forms of the functionalized o-aminophenol H2LC(O)Ph were synthesized. The intermediate spin state (SCo = 1) CoIII center was found for compound 1. The cyclic voltammogram of derivative 1 contains two oxidative processes and one reductive redox process as well as an additional multi-electron wave at high negative potentials above -2 V, which can involve both the ligand and metal center. One-electron oxidation of 1 by silver triflate produces the [(imSQC(O)Ph)CoII(imQC(O)Ph)]OTf·2toluene (2) derivative with the trigonal prismatic coordination environment of the metal arising from the additional coordination of -C(O)Ph hemilabile groups. This is a first example of a trigonal prismatic coordination polyhedron in cobalt-based complexes featuring o-iminobenzoquinone ligands. The trigonal prismatic geometry achieved by the unique flexibility of the ligand allows metal-to-ligand redox-induced electron transfer (RIET). Chemical oxidation of complex 1 promotes the reduction of CoIII to CoII in compound 2 due to the redox-active nature of o-iminobenzoquinonate ligands. Remarkably, this is the first example of RIET in cobalt-based derivatives with this type of ligand. The oxidative states of the ligands and cobalt ion in both complexes were unequivocally established according to the X-ray data collection by using the utility of "metric oxidation state" (MOS). The spin states of the metal centers were unambiguously determined by density functional theory. The strong antiferromagnetic exchange via metal-ligand interactions is dominant in compounds 1 and 2, giving the doublet (S = 1/2) and triplet (S = 1) ground spin state, respectively.
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Affiliation(s)
- Alexandr V Piskunov
- G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Laboratory of Organoelement Compounds, 49 Tropinina Street, 603137, Nizhny Novgorod, Russian Federation.
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Maciulis NA, Schaugaard RN, Losovyj Y, Chen CH, Pink M, Caulton KG. Seeking Redox Activity in a Tetrazinyl Pincer Ligand: Installing Zerovalent Cr and Mo. Inorg Chem 2018; 57:12671-12682. [DOI: 10.1021/acs.inorgchem.8b01761] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicholas A. Maciulis
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Richard N. Schaugaard
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Yaroslav Losovyj
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Chun-Hsing Chen
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Maren Pink
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Kenneth G. Caulton
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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35
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36
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Rudenko AE, Clayman NE, Walker KL, Maclaren JK, Zimmerman PM, Waymouth RM. Ligand-Induced Reductive Elimination of Ethane from Azopyridine Palladium Dimethyl Complexes. J Am Chem Soc 2018; 140:11408-11415. [PMID: 30160962 DOI: 10.1021/jacs.8b06398] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Reductive elimination (RE) is a critical step in many catalytic processes. The reductive elimination of unsaturated groups (aryl, vinyl and ethynyl) from Pd(II) species is considerably faster than RE of saturated alkyl groups. Pd(II) dimethyl complexes ligated by chelating diimine ligands are stable toward RE unless subjected to a thermal or redox stimulus. Herein, we report the spontaneous RE of ethane from (azpy)PdMe2 complexes and the unique role of the redox-active azopyridine (azpy) ligands in facilitating this reaction. The (azpy)PdMe2 complexes are air- and moisture-stable in the solid form, but they readily produce ethane upon dissolution in polar solvents at temperatures from 10 °C to room temperature without the need for an external oxidant or elevated temperatures. Experimental and computational studies indicate that a bimolecular methyl transfer precedes the reductive elimination step, where both steps are facilitated by the redox-active azopyridine ligand.
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Affiliation(s)
- Andrey E Rudenko
- Department of Chemistry , Stanford University , Stanford , California 94305-5080 , United States
| | - Naomi E Clayman
- Department of Chemistry , Stanford University , Stanford , California 94305-5080 , United States
| | - Katherine L Walker
- Department of Chemistry , Stanford University , Stanford , California 94305-5080 , United States
| | - Jana K Maclaren
- Stanford Nano Shared Facilities , Stanford University , 476 Lomita Mall , Stanford , California 94305 , United States
| | - Paul M Zimmerman
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109-1055 , United States
| | - Robert M Waymouth
- Department of Chemistry , Stanford University , Stanford , California 94305-5080 , United States
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Schrempp DF, Kaifer E, Himmel HJ. Solvent Control of Ligand-Metal Electron Transfer in Mononuclear Copper Complexes with Redox-Active Bisguanidine Ligands. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800525] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- David F. Schrempp
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
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38
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Broere DLJ, Mercado BQ, Bill E, Lancaster KM, Sproules S, Holland PL. Alkali Cation Effects on Redox-Active Formazanate Ligands in Iron Chemistry. Inorg Chem 2018; 57:9580-9591. [PMID: 29629752 PMCID: PMC6116910 DOI: 10.1021/acs.inorgchem.8b00226] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Noncovalent interactions of organic moieties with Lewis acidic alkali cations can greatly affect structure and reactivity. Herein, we describe the effects of interactions with alkali-metal cations within a series of reduced iron complexes bearing a redox-active formazanate ligand, in terms of structures, magnetism, spectroscopy, and reaction rates. In the absence of a crown ether to sequester the alkali cation, dimeric complexes are isolated wherein the formazanate has rearranged to form a five-membered metallacycle. The dissociation of these dimers is dependent on the binding mode and size of the alkali cation. In the dimers, the formazanate ligands are radical dianions, as shown by X-ray absorption spectroscopy, Mössbauer spectroscopy, and analysis of metrical parameters. These experimental measures are complemented by density functional theory calculations that show the spin density on the bridging ligands.
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Affiliation(s)
- Daniel L J Broere
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , United States
| | - Brandon Q Mercado
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , United States
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36 , D-45470 Mülheim an der Ruhr , Germany
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Stephen Sproules
- WestCHEM, School of Chemistry , University of Glasgow , Glasgow G12 8QQ , United Kingdom
| | - Patrick L Holland
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , United States
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Hanft A, Lichtenberg C. Aminotroponiminates: ligand-centred, reversible redox events under oxidative conditions in sodium and bismuth complexes. Dalton Trans 2018; 47:10578-10589. [DOI: 10.1039/c8dt01019f] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Redox-active bismuth complexes based on a new aminotroponiminate ligand with ferrocenyl substituents have been synthesised and characterised.
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Affiliation(s)
- Anna Hanft
- Department of Inorganic Chemistry
- Julius-Maximilians-Universität Würzburg
- D-97074 Würzburg
- Germany
| | - Crispin Lichtenberg
- Department of Inorganic Chemistry
- Julius-Maximilians-Universität Würzburg
- D-97074 Würzburg
- Germany
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40
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Ziesak A, Steuer L, Kaifer E, Wagner N, Beck J, Wadepohl H, Himmel HJ. Intramolecular metal–ligand electron transfer triggered by co-ligand substitution. Dalton Trans 2018; 47:9430-9441. [DOI: 10.1039/c8dt01234b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Labile co-ligands are attached to a dinuclear copper(i) complex with a redox-active bridging guanidine ligand. Their substitution triggers electron-transfer from the copper atoms to the guanidine.
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Affiliation(s)
- Alexandra Ziesak
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Lena Steuer
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Norbert Wagner
- Institut für Anorganische Chemie
- Universität Bonn
- 53121 Bonn
- Germany
| | - Johannes Beck
- Institut für Anorganische Chemie
- Universität Bonn
- 53121 Bonn
- Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
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41
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Harris CF, Bayless MB, van Leest NP, Bruch QJ, Livesay BN, Bacsa J, Hardcastle KI, Shores MP, de Bruin B, Soper JD. Redox-Active Bis(phenolate) N-Heterocyclic Carbene [OCO] Pincer Ligands Support Cobalt Electron Transfer Series Spanning Four Oxidation States. Inorg Chem 2017; 56:12421-12435. [DOI: 10.1021/acs.inorgchem.7b01906] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Caleb F. Harris
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Michael B. Bayless
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Nicolaas P. van Leest
- Van ’t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Quinton J. Bruch
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Brooke N. Livesay
- Department of Chemistry, Colorado State University, Fort
Collins, Colorado 80523-1872, United States
| | - John Bacsa
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
- X-ray Crystallography Center, Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Kenneth I. Hardcastle
- X-ray Crystallography Center, Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Matthew P. Shores
- Department of Chemistry, Colorado State University, Fort
Collins, Colorado 80523-1872, United States
| | - Bas de Bruin
- Van ’t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Jake D. Soper
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
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42
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Bipyridyl– and pyridylquinolyl–phenothiazine structures as potential photoactive ligands: Syntheses and complexation to palladium. Tetrahedron Lett 2017. [DOI: 10.1016/j.tetlet.2017.06.073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Ortuño MA, Cramer CJ. Multireference Electronic Structures of Fe–Pyridine(diimine) Complexes over Multiple Oxidation States. J Phys Chem A 2017; 121:5932-5939. [DOI: 10.1021/acs.jpca.7b06032] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Manuel A. Ortuño
- Department of Chemistry,
Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Christopher J. Cramer
- Department of Chemistry,
Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Curcio M, Pankhurst JR, Sproules S, Mignard D, Love JB. Triggering Redox Activity in a Thiophene Compound: Radical Stabilization and Coordination Chemistry. Angew Chem Int Ed Engl 2017; 56:7939-7943. [PMID: 28471076 DOI: 10.1002/anie.201703576] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Indexed: 12/24/2022]
Abstract
The synthesis, metalation, and redox properties of an acyclic bis(iminothienyl)methene L- are presented. This π-conjugated anion displayed pronounced redox activity, undergoing facile one-electron oxidation to the acyclic, metal-free, neutral radical L. on reaction with FeBr2 . In contrast, the reaction of L- with CuI formed the unique, neutral Cu2 I2 (L. ) complex of a ligand-centered radical, whereas reaction with the stronger oxidant AgBF4 formed the metal-free radical dication L.2+ .
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Affiliation(s)
- Massimiliano Curcio
- EaStCHEM School of Chemistry and School of Engineering, University of Edinburgh, The King's Buildings, Edinburgh, EH9 3FJ, UK
| | - James R Pankhurst
- EaStCHEM School of Chemistry and School of Engineering, University of Edinburgh, The King's Buildings, Edinburgh, EH9 3FJ, UK
| | - Stephen Sproules
- WestCHEM School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Dimitri Mignard
- EaStCHEM School of Chemistry and School of Engineering, University of Edinburgh, The King's Buildings, Edinburgh, EH9 3FJ, UK
| | - Jason B Love
- EaStCHEM School of Chemistry and School of Engineering, University of Edinburgh, The King's Buildings, Edinburgh, EH9 3FJ, UK
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45
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Curcio M, Pankhurst JR, Sproules S, Mignard D, Love JB. Triggering Redox Activity in a Thiophene Compound: Radical Stabilization and Coordination Chemistry. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201703576] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Massimiliano Curcio
- EaStCHEM School of Chemistry and School of Engineering; University of Edinburgh; The King's Buildings Edinburgh EH9 3FJ UK
| | - James R. Pankhurst
- EaStCHEM School of Chemistry and School of Engineering; University of Edinburgh; The King's Buildings Edinburgh EH9 3FJ UK
| | - Stephen Sproules
- WestCHEM School of Chemistry; University of Glasgow; Glasgow G12 8QQ UK
| | - Dimitri Mignard
- EaStCHEM School of Chemistry and School of Engineering; University of Edinburgh; The King's Buildings Edinburgh EH9 3FJ UK
| | - Jason B. Love
- EaStCHEM School of Chemistry and School of Engineering; University of Edinburgh; The King's Buildings Edinburgh EH9 3FJ UK
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