1
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Juda CE, Handford RC, Bartholomew AK, Powers TM, Gu NX, Meyer E, Roth N, Chen YS, Zheng SL, Betley TA. Cluster dynamics of heterometallic trinuclear clusters during ligand substitution, redox chemistry, and group transfer processes. Chem Sci 2024; 15:8242-8248. [PMID: 38817579 PMCID: PMC11134326 DOI: 10.1039/d3sc03606e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 02/04/2024] [Indexed: 06/01/2024] Open
Abstract
Stepwise metalation of the hexadentate ligand tbsLH6 (tbsLH6 = 1,3,5-C6H9(NHC6H4-o-NHSiMe2tBu)3) affords bimetallic trinuclear clusters (tbsL)Fe2Zn(thf) and (tbsL)Fe2Zn(py). Reactivity studies were pursued to understand metal atom lability as the clusters undergo ligand substitution, redox chemistry, and group transfer processes. Chloride addition to (tbsL)Fe2Zn(thf) resulted in a mixture of species including both all-zinc and all-iron products. Addition of ArN3 (Ar = Ph, 3,5-(CF3)2C6H3) to (tbsL)Fe2Zn(py) yielded a mixture of two trinuclear products: (tbsL)Fe3(μ3-NAr) and (tbsL)Fe2Zn(μ3-NAr)(py). The two imido species were separated via crystallization, and outer sphere reduction of (tbsL)Fe2Zn(μ3-NAr)(py) resulted in the formation of a single product, [2,2,2-crypt(K)][(tbsL)Fe2Zn(μ3-NAr)]. These results provide insight into the relationship between heterometallic cluster structure and substitutional lability and could help inform both future catalyst design and our understanding of metal atom lability in bioinorganic systems.
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Affiliation(s)
- Cristin E Juda
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Rex C Handford
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | | | - Tamara M Powers
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Nina X Gu
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Elisabeth Meyer
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Nikolaj Roth
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Yu-Sheng Chen
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Shao-Liang Zheng
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Theodore A Betley
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
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2
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Osei MK, Mirzaei S, Mirzaei MS, Valles A, Hernández Sánchez R. Reversible dioxygen uptake at [Cu 4] clusters. Chem Sci 2024; 15:5327-5332. [PMID: 38577358 PMCID: PMC10988628 DOI: 10.1039/d3sc06390a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/04/2024] [Indexed: 04/06/2024] Open
Abstract
Dioxygen binding solely through non-covalent interactions is rare. In living systems, dioxygen transport takes place via iron or copper-containing biological cofactors. Specifically, a reversible covalent interaction is established when O2 binds to the mono or polynuclear metal center. However, O2 stabilization in the absence of covalent bond formation is challenging and rarely observed. Here, we demonstrate a unique example of reversible non-covalent binding of dioxygen within the cavity of a well-defined synthetic all-Cu(i) tetracopper cluster.
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Affiliation(s)
- Manasseh Kusi Osei
- Department of Chemistry, Rice University 6100 Main St. Houston Texas USA
| | - Saber Mirzaei
- Department of Chemistry, Rice University 6100 Main St. Houston Texas USA
- Department of Chemistry, University of Pittsburgh 219 Parkman Ave. Pittsburgh Pennsylvania 15260 USA
| | - M Saeed Mirzaei
- Department of Chemistry, Rice University 6100 Main St. Houston Texas USA
| | - Agustin Valles
- Department of Chemistry, Rice University 6100 Main St. Houston Texas USA
| | - Raúl Hernández Sánchez
- Department of Chemistry, Rice University 6100 Main St. Houston Texas USA
- Department of Chemistry, University of Pittsburgh 219 Parkman Ave. Pittsburgh Pennsylvania 15260 USA
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3
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Juda CE, Casaday CE, Clarke RM, Litak NP, Campbell BM, Chang T, Zheng SL, Chen YS, Betley TA. Lewis Acid Supported Nickel Nitrenoids. Angew Chem Int Ed Engl 2023; 62:e202313156. [PMID: 37830508 DOI: 10.1002/anie.202313156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/12/2023] [Accepted: 10/13/2023] [Indexed: 10/14/2023]
Abstract
Metalation of the polynucleating ligand F,tbs LH6 (1,3,5-C6 H9 (NC6 H3 -4-F-2-NSiMe2 t Bu)3 ) with two equivalents of Zn(N(SiMe3 )2 )2 affords the dinuclear product (F,tbs LH2 )Zn2 (1), which can be further deprotonated to yield (F,tbs L)Zn2 Li2 (OEt2 )4 (2). Transmetalation of 2 with NiCl2 (py)2 yields the heterometallic, trinuclear cluster (F,tbs L)Zn2 Ni(py) (3). Reduction of 3 with KC8 affords [KC222 ][(F,tbs L)Zn2 Ni] (4) which features a monovalent Ni centre. Addition of 1-adamantyl azide to 4 generates the bridging μ3 -nitrenoid adduct [K(THF)3 ][(F,tbs L)Zn2 Ni(μ3 -NAd)] (5). EPR spectroscopy reveals that the anionic cluster possesses a doublet ground state (S =1 / 2 ${{ 1/2 }}$ ). Cyclic voltammetry of 5 reveals two fully reversible redox events. The dianionic nitrenoid [K2 (THF)9 ][(F,tbs L)Zn2 Ni(μ3 -NAd)] (6) was isolated and characterized while the neutral redox isomer was observed to undergo both intra- and intermolecular H-atom abstraction processes. Ni K-edge XAS studies suggest a divalent oxidation state for the Ni centres in both the monoanionic and dianionic [Zn2 Ni] nitrenoid complexes. However, DFT analysis suggests Ni-borne oxidation for 5.
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Affiliation(s)
- Cristin E Juda
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, MA 02138, USA
| | - Claire E Casaday
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, MA 02138, USA
| | - Ryan M Clarke
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, MA 02138, USA
| | - Nicholas P Litak
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, MA 02138, USA
| | - Brandon M Campbell
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, MA 02138, USA
| | - Tieyan Chang
- ChemMatCARS Beamline, The University of Chicago, Advanced Photon Source, Argonne, IL 60429, USA
| | - Shao-Liang Zheng
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, MA 02138, USA
| | - Yu-Sheng Chen
- ChemMatCARS Beamline, The University of Chicago, Advanced Photon Source, Argonne, IL 60429, USA
| | - Theodore A Betley
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, MA 02138, USA
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4
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Scott AG, Galico DA, Bogacz I, Oyala PH, Yano J, Suturina EA, Murugesu M, Agapie T. High-Spin and Reactive Fe 13 Cluster with Exposed Metal Sites. Angew Chem Int Ed Engl 2023; 62:e202313880. [PMID: 37871234 PMCID: PMC10962695 DOI: 10.1002/anie.202313880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 10/23/2023] [Accepted: 10/23/2023] [Indexed: 10/25/2023]
Abstract
Atomically defined large metal clusters have applications in new reaction development and preparation of materials with tailored properties. Expanding the synthetic toolbox for reactive high nuclearity metal complexes, we report a new class of Fe clusters, Tp*4 W4 Fe13 S12 , displaying a Fe13 core with M-M bonds that has precedent only in main group and late metal chemistry. M13 clusters with closed shell electron configurations can show significant stability and have been classified as superatoms. In contrast, Tp*4 W4 Fe13 S12 displays a large spin ground state of S=13. This compound performs small molecule activations involving the transfer of up to 12 electrons resulting in significant cluster rearrangements.
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Affiliation(s)
- Anna G. Scott
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 (USA)
| | - Diogo Alves Galico
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1 N6 N5 (Canada)
| | - Isabel Bogacz
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory Berkeley, CA 94720 (USA)
| | - Paul H. Oyala
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 (USA)
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory Berkeley, CA 94720 (USA)
| | | | - Muralee Murugesu
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1 N6 N5 (Canada)
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 (USA)
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5
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Nelson YA, Irshad A, Kim S, Waddington MA, Salamat CZ, Gembicky M, Rheingold AL, Carta V, Tolbert SH, Narayan SR, Spokoyny AM. Vertex Differentiation Strategy for Tuning the Physical Properties of closo-Dodecaborate Weakly Coordinating Anions. Inorg Chem 2023; 62:15084-15093. [PMID: 37667823 PMCID: PMC11152248 DOI: 10.1021/acs.inorgchem.3c01992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
We report the synthesis and characterization of various compounds containing the 1,7,9-hydroxylated closo-dodecahydrododecaborate (B12H9(OH)32-) cluster motif. Specifically, we show how the parent compound can be synthesized on the multigram scale and further perhalogenated, leading to a new class of vertex-differentiated weakly coordinating anions. We show that a postmodification of the hydroxyl groups by alkylation affords further opportunities for tailoring these anions' stability, steric bulk, and solubility properties. The resulting dodecaborate-based salts were subjected to a full thermal and electrochemical stability evaluation, showing that many of these anions maintain thermal stability up to 500 °C and feature no redox activity below ∼1 V vs Fc/Fc+. Mixed hydroxylated/halogenated clusters show enhanced solubility compared to their purely halogenated analogs and retain weakly coordinating properties in the solid state, as demonstrated by ionic conductivity measurements of their Li+ salts.
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Affiliation(s)
- Yessica A Nelson
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Ahamed Irshad
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Sangmin Kim
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Mary A Waddington
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Charlene Z Salamat
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Milan Gembicky
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Arnold L Rheingold
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Veronica Carta
- Department of Chemistry and Biochemistry, University of California, Riverside, Riverside, California 92521, United States
| | - Sarah H Tolbert
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Sri R Narayan
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Alexander M Spokoyny
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
- California NanoSystems Institute (CNSI), University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, California 90095, United States
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Iron(II) Mediated Supramolecular Architectures with Schiff Bases and Their Spin-Crossover Properties. Molecules 2023; 28:molecules28031012. [PMID: 36770685 PMCID: PMC9919814 DOI: 10.3390/molecules28031012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/11/2023] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
Supramolecular architectures, which are formed through the combination of inorganic metal cations and organic ligands by self-assembly, are one of the techniques in modern chemical science. This kind of multi-nuclear system in various dimensionalities can be implemented in various applications such as sensing, storage/cargo, display and molecular switching. Iron(II) mediated spin-crossover (SCO) supramolecular architectures with Schiff bases have attracted the attention of many investigators due to their structural novelty as well as their potential application possibilities. In this paper, we review a number of supramolecular SCO architectures of iron(II) with Schiff base ligands exhibiting varying geometrical possibilities. The structural and SCO behavior of these complexes are also discussed in detail.
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Sunada Y, Yamaguchi K, Suzuki K. “Template synthesis” of discrete metal clusters with two- or three-dimensional architectures. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Kephart JA, Mitchell BS, Kaminsky W, Velian A. Multi-active Site Dynamics on a Molecular Cr/Co/Se Cluster Catalyst. J Am Chem Soc 2022; 144:9206-9211. [PMID: 35593888 DOI: 10.1021/jacs.2c00234] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This study uncovers the interconnected reactivity of the three catalytically active sites of an atomically precise nanocluster Cr3(py)3Co6Se8L6 (1(py)3, L = Ph2PNTol-, Ph = phenyl, Tol = 4-tolyl). Catalytic and stoichiometric studies into tosyl azide activation and carbodiimide formation enabled the isolation and crystallographic characterization of key catalytically competent metal-imido intermediates, including the tris(imido) cluster 1(NTs)3, the catalytic resting state 1(NTs)3(CNtBu)3, and the site-differentiated mono(imido) cluster 1(NTs)(CNtBu)2. In the stoichiometric regime, nitrene transfer proceeds via a stepwise mechanism, with the three active sites engaging sequentially to produce carbodiimide. Moreover, the chemical state of neighboring active sites was found to regulate the affinity for substrates of an individual Cr-imido edge site, as revealed by comparative structural analysis and CNtBu binding studies.
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Affiliation(s)
- Jonathan A Kephart
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Benjamin S Mitchell
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Werner Kaminsky
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Alexandra Velian
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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Bartholomew AK, Musgrave RA, Anderton KJ, Juda CE, Dong Y, Bu W, Wang SY, Chen YS, Betley TA. Revealing redox isomerism in trichromium imides by anomalous diffraction. Chem Sci 2021; 12:15739-15749. [PMID: 35003606 PMCID: PMC8654065 DOI: 10.1039/d1sc04819h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/02/2021] [Indexed: 12/02/2022] Open
Abstract
In polynuclear biological active sites, multiple electrons are needed for turnover, and the distribution of these electrons among the metal sites is affected by the structure of the active site. However, the study of the interplay between structure and redox distribution is difficult not only in biological systems but also in synthetic polynuclear clusters since most redox changes produce only one thermodynamically stable product. Here, the unusual chemistry of a sterically hindered trichromium complex allowed us to probe the relationship between structural and redox isomerism. Two structurally isomeric trichromium imides were isolated: asymmetric terminal imide (tbsL)Cr3(NDipp) and symmetric, μ3-bridging imide (tbsL)Cr3(μ3–NBn) ((tbsL)6− = (1,3,5-C6H9(NC6H4-o-NSitBuMe2)3)6−). Along with the homovalent isocyanide adduct (tbsL)Cr3(CNBn) and the bisimide (tbsL)Cr3(μ3–NPh)(NPh), both imide isomers were examined by multiple-wavelength anomalous diffraction (MAD) to determine the redox load distribution by the free refinement of atomic scattering factors. Despite their compositional similarities, the bridging imide shows uniform oxidation of all three Cr sites while the terminal imide shows oxidation at only two Cr sites. Further oxidation from the bridging imide to the bisimide is only borne at the Cr site bound to the second, terminal imido fragment. Thus, depending on the structural motifs present in each [Cr3] complex, MAD revealed complete localization of oxidation, partial localization, and complete delocalization, all supported by the same hexadentate ligand scaffold. Application of high-resolution Multiwavelength Anomalous Diffraction (MAD) allows the assignment of localized, partly delocalized, and fully delocalized oxidation in a series of trichromium imide isomers.![]()
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Affiliation(s)
| | - Rebecca A Musgrave
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Kevin J Anderton
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Cristin E Juda
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Yuyang Dong
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
| | - Wei Bu
- ChemMatCARS, The University of Chicago Argonne Illinois 60439 USA
| | - Su-Yin Wang
- ChemMatCARS, The University of Chicago Argonne Illinois 60439 USA
| | - Yu-Sheng Chen
- ChemMatCARS, The University of Chicago Argonne Illinois 60439 USA
| | - Theodore A Betley
- Department of Chemistry and Chemical Biology, Harvard University Cambridge MA 02139 USA
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10
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Kondo M, Masaoka S. Pentanuclear Scaffold: A Molecular Platform for Small-Molecule Conversions. Acc Chem Res 2020; 53:2140-2151. [PMID: 32870647 DOI: 10.1021/acs.accounts.0c00186] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Small-molecule conversions involving multielectron transfer processes enable the conversion of earth-abundant materials into valuable chemicals and are regarded as a solution for environmental and energy shortage problems. In this context, the development of artificial catalysts that promote these reactions is an important research target. In nature, metalloenzymes that contain multinuclear metal complexes as active sites are known to efficiently catalyze reactions under mild conditions. Therefore, using multinuclear metal complexes as artificial catalysts can be an attractive strategy for small-molecule conversions involving multielectron transfer processes. However, multinuclear-metal-complex-based catalysts for these reactions have not been well established. In this Account, we describe our recent advances in the development of multinuclear metal complexes as catalysts for small-molecule conversion, mainly focusing on water oxidation. As small-molecule conversions involving multielectron transfer processes consists of two essential processes, (1) the transfer of multiple electrons and (2) the formation/cleavage of covalent bond(s), catalysts for these reactions should facilitate both steps. Therefore, we assumed that the assembly of redox-active metal ions and the cooperative effect of neighboring coordinatively unsaturated metal ions can promote these processes. On the basis of this assumption, we employed a pentanuclear metal complex as a molecular scaffold for the catalyst. The scaffold has a pentanuclear structure with quasi-D3 symmetry and consists of a [M3(μ3-X)] core (X = O2- or OH-) wrapped by two [M(μ-bpp)3] units (Hbpp = 3,5-bis(2-pyridyl)pyrazole). The metal ions in the triangular core are coordinatively unsaturated, whereas the metal ions at the apical positions are coordinatively saturated. In other words, the pentanuclear scaffold possesses multiple redox-active centers and coordinatively unsaturated sites. It should also be noted that the electron transfer ability of the complex changes dramatically depending on the identity of the constituent metal ions. The iron derivative of the pentanuclear scaffold was found to serve as an electrocatalyst for water oxidation (2H2O → O2 + 4e- + 4H+) with a high reaction rate and excellent robustness. The substitution of metal ions in the pentanuclear scaffold to cobalt ions resulted in the development of a catalyst for CO2 reduction. Furthermore, we investigated the effect of substituents on the ligands of the pentanuclear iron complex and succeeded in precisely manipulating the electron transfer possess. These results clearly demonstrate that the pentanuclear scaffold is an attractive platform for catalysts for small-molecule conversions. Additionally, the intrinsic features of the multinuclear catalytic system, which are totally different from those of conventional mononuclear-metal-complex-based catalysts, are disclosed. In reactions mediated by multinuclear complexes, the multinuclear core can initially accumulate the charge required for catalysis to reach the catalytically active state. Subsequently, the catalyst in the active state reacts with the substrate, initiating electron transfer to the substrate and rearrangement of covalent bonds in the substrate to afford the product. In such a mechanism, the desired number of electrons can be transferred to the substrates in an on-demand fashion, and the formation of undesired chemical species in the targeted catalysis may be prevented. This feature of multinuclear-metal-complex-based catalysts will achieve demanding small-molecule conversions with a high reaction rate, selectivity, and durability.
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Affiliation(s)
- Mio Kondo
- Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shigeyuki Masaoka
- Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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11
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Zhang S, Wang Q, Thierer LM, Weberg AB, Gau MR, Carroll PJ, Tomson NC. Tuning Metal-Metal Interactions through Reversible Ligand Folding in a Series of Dinuclear Iron Complexes. Inorg Chem 2019; 58:12234-12244. [PMID: 31448589 DOI: 10.1021/acs.inorgchem.9b01673] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A dinucleating macrocyclic ligand with two redox-active, pyridyldiimine components was shown to undergo reversible ligand folding to accommodate various substitution patterns, metal ion spin states, and degrees of Fe-Fe bonding within the cluster. An unfolded-ligand geometry with a rectangular Fe2(μ-Cl)2 core and an Fe-Fe distance of 3.3262(5) Å served as a direct precursor to two different folded-ligand complexes. Chemical reduction in the presence of PPh3 resulted in a diamagnetic, folded ligand complex with an Fe-Fe bonding interaction (dFe-Fe = 2.7096(17) Å) between two intermediate spin (SFe = 1) Fe(II) centers. Ligand folding was also induced through anion exchange on the unfolded-ligand species, producing a complex with three PhS- ligands and a temperature-dependent Fe-Fe distance. In this latter example, the weak ligand field of the thiolate ligands led to a product with weakly coupled, high-spin Fe(II) ions (SFe = 2; J = -50.1 cm-1) that form a bonding interaction in the ground state and a nonbonding interaction in the excited state(s), as determined by SQUID magnetometry and variable temperature crystallography. Finally, both folded-ligand complexes were shown to reform an unfolded-ligand geometry through convergent syntheses of a complex with an Fe-Fe bonded Fe2(μ-SPh)2 core (dFe-Fe = 2.7320(11) Å). Experimentally validated DFT calculations were used to investigate the electronic structures of all species as a way to understand the origin of Fe-Fe bonding interactions, the extent of ligand reduction, and the nature of the spin systems that result from multiple, weakly interacting spin centers.
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Affiliation(s)
- Shaoguang Zhang
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Qiuran Wang
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Laura M Thierer
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Alexander B Weberg
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Michael R Gau
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Patrick J Carroll
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Neil C Tomson
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
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