1
|
Weiser J, Cui J, Dewhurst RD, Braunschweig H, Engels B, Fantuzzi F. Structure and bonding of proximity-enforced main-group dimers stabilized by a rigid naphthyridine diimine ligand. J Comput Chem 2023; 44:456-467. [PMID: 36054757 DOI: 10.1002/jcc.26994] [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: 04/03/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 12/31/2022]
Abstract
The development of ligands capable of effectively stabilizing highly reactive main-group species has led to the experimental realization of a variety of systems with fascinating properties. In this work, we computationally investigate the electronic, structural, energetic, and bonding features of proximity-enforced group 13-15 homodimers stabilized by a rigid expanded pincer ligand based on the 1,8-naphthyridine (napy) core. We show that the redox-active naphthyridine diimine (NDI) ligand enables a wide variety of structural motifs and element-element interaction modes, the latter ranging from isolated, element-centered lone pairs (e.g., E = Si, Ge) to cases where through-space π bonds (E = Pb), element-element multiple bonds (E = P, As) and biradical ground states (E = N) are observed. Our results hint at the feasibility of NDI-E2 species as viable synthetic targets, highlighting the versatility and potential applications of napy-based ligands in main-group chemistry.
Collapse
Affiliation(s)
- Jonas Weiser
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Physical and Theoretical Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Jingjing Cui
- School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan, People's Republic of China
| | - Rian D Dewhurst
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Bernd Engels
- Institute for Physical and Theoretical Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Felipe Fantuzzi
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,School of Chemistry and Forensic Science, University of Kent, Canterbury, UK
| |
Collapse
|
2
|
Vetter G, Białońska A, Krzyszowska P, Koniarz S, Pacholska‐Dudziak E. Two Rhodium(III) Ions Confined in a [18]Porphyrin Frame: 5,10,15,20‐Tetraaryl‐21,23‐Dirhodaporphyrin. Chemistry 2022; 28:e202201513. [PMID: 35665970 PMCID: PMC9545270 DOI: 10.1002/chem.202201513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Indexed: 11/23/2022]
Abstract
Tetraaryl‐21,23‐dirhodaporphyrin and a series of related monorhodaporphyrins have been obtained by tellurium‐to‐rhodium exchange in a reaction of tetraaryl‐21,23‐ditelluraporphyrin with [RhCl(CO)2]2. These organometallic metallaporphyrins contain rhodium(III) centers embedded in rhodacyclopentadiene rings, incorporated within the porphyrin frames. The skeletons of 21,23‐dirhodaporphyrin and 21‐rhoda‐23‐telluraporphyrin are strongly deformed in‐plane from the rectangular shape typical for porphyrins, due to rhodium(III) coordination preferences, the large size of the two core atoms, and the porphyrin skeleton constrains. These two metallaporphyrins exhibit fluxional behavior, as studied by 1H NMR and DFT, involving the in‐plane motion and the switch of the rhodium center(s) between two nitrogen donors. A side product detected in the reaction mixture, 21‐oxa‐23‐rhodaporphyrin, results from tellurium‐to‐oxygen exchange, occurring in parallel to the tellurium‐to‐rhodium exchange. The reaction paths and mechanisms have been analyzed. The title 21,23‐dirhodaporphyrin contains a bridged bimetallic unit, Rh2Cl2, in the center of the macrocycle, with two rhodium(III) ions lying approximately in the plane of the porphyrinoid skeleton. The geometry of the implanted Rh2Cl2 unit is affected by macrocyclic constrains.
Collapse
Affiliation(s)
- Grzegorz Vetter
- Faculty of Chemistry University of Wroclaw ul. Joliot-Curie 14 50-383 Wroclaw Poland
| | - Agata Białońska
- Faculty of Chemistry University of Wroclaw ul. Joliot-Curie 14 50-383 Wroclaw Poland
| | - Paulina Krzyszowska
- Faculty of Chemistry University of Wroclaw ul. Joliot-Curie 14 50-383 Wroclaw Poland
| | - Sebastian Koniarz
- Faculty of Chemistry University of Wroclaw ul. Joliot-Curie 14 50-383 Wroclaw Poland
| | - Ewa Pacholska‐Dudziak
- Faculty of Chemistry University of Wroclaw ul. Joliot-Curie 14 50-383 Wroclaw Poland
| |
Collapse
|
3
|
Abstract
The Gouterman four-orbital model conceptualizes porphyrin UV-visible spectra as dominated by four frontier molecular orbitals-two nearly degenerate HOMOs and two exactly degenerate LUMOS under D 4h symmetry. These are well separated from all the other molecular orbitals, and normal spectra involve transitions among these MOs. Unusual spectra occur when additional orbitals appear in this energy range, typically as a consequence of the central coordinated atom. For example, metals with empty d orbitals in a suitable energy range may lead to charge transfer from porphyrin (ligand) to metal, that is, so-called LMCT transitions. Metals with filled p or d orbitals may lead to charge transfer from metal to porphyrin, MLCT transitions. These cases lead to additional peaks and/or significant redshifts in the spectra and were classified as hyperporphyrins by Gouterman. Cases in which spectra are blueshifted were classified as hypsoporphyrins; they are common for relatively electronegative late transition metal porphyrins. Many of the same principles apply to porphyrin analogues, especially corroles. In this Perspective, we focus on two newer classes of hyperporphyrins: one reflecting substituent effects in protonated or deprotonated free-base tetraphenyporphyrins and the other reflecting "noninnocent" interactions between central metal ions and corroles. Hyperporphyrin effects on spectra can be dramatic, yet they can be generated by relatively simple changes and subtle structural variations, such as acid-base reactions or the selection of a central metal ion. These concepts suggest strategies for engineering porphyrin or porphyrinoid dyes for specific applications, especially those requiring far-red or near-infrared absorption or emission.
Collapse
Affiliation(s)
- Carl C. Wamser
- Department
of Chemistry, Portland State University, Portland, Oregon 97207-0751, United States
| | - Abhik Ghosh
- Department
of Chemistry and Arctic Center for Sustainable Energy, UiT − The Arctic University of Norway, N-9037 Tromsø, Norway
| |
Collapse
|
4
|
Greb L. Valence Tautomerism of p‐Block Element Compounds – An Eligible Phenomenon for Main Group Catalysis? Eur J Inorg Chem 2021; 2022:e202100871. [PMID: 35910784 PMCID: PMC9306562 DOI: 10.1002/ejic.202100871] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/12/2021] [Indexed: 01/03/2023]
Abstract
Valence tautomerism has had a remarkable impact on several branches of transition metal chemistry. By switching between different valence tautomeric states, physicochemical properties and reactivities can be triggered reversibly. Is this phenomenon transferrable into the p‐block – or is it already happening there? This Perspective collects observations of p‐block element‐ligand systems that might be assignable to valence tautomerism. Further, it discusses occurrences in p‐block element compounds that exhibit the related effect of redox‐induced electron transfer. As disclosed, the concept of valence tautomerism with p‐block elements is at a very early stage. However, given the substantial disparity in the properties of those elements in different redox states, it might offer a valid extension for future developments in main group catalysis.
Collapse
Affiliation(s)
- Lutz Greb
- Anorganische Chemie Freie Universität Berlin Fabeckstr. 34–36 14195 Berlin Germany
- Anorganisch-Chemisches Institut Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| |
Collapse
|
5
|
|
6
|
Curtis CJ, Astashkin AV, Conradie J, Ghosh A, Tomat E. Ligand-Centered Triplet Diradical Supported by a Binuclear Palladium(II) Dipyrrindione. Inorg Chem 2021; 60:12457-12466. [PMID: 34347474 PMCID: PMC8389801 DOI: 10.1021/acs.inorgchem.1c01691] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Oligopyrroles
form
a versatile class of redox-active ligands and
electron reservoirs. Although the stabilization of radicals within
oligopyrrolic π systems is more common for macrocyclic ligands,
bidentate dipyrrindiones are emerging as compact platforms for one-electron
redox chemistry in transition-metal complexes. We report the synthesis
of a bis(aqua) palladium(II) dipyrrindione complex and its deprotonation-driven
dimerization to form a hydroxo-bridged binuclear complex in the presence
of water or triethylamine. Electrochemical, spectroelectrochemical,
and computational analyses of the binuclear complex indicate the accessibility
of two quasi-reversible ligand-centered reduction processes. The product
of a two-electron chemical reduction by cobaltocene was isolated and
characterized. In the solid state, this cobaltocenium salt features
a folded dianionic complex that maintains the hydroxo bridges between
the divalent palladium centers. X-band and Q-band EPR spectroscopic
experiments and DFT computational analysis allow assignment of the
dianionic species as a diradical with spin density almost entirely
located on the two dipyrrindione ligands. As established from the
EPR temperature dependence, the associated exchange coupling is weak
and antiferromagnetic (J ≈ −2.5 K),
which results in a predominantly triplet state at the temperatures
at which the measurements have been performed. The coordination and redox chemistry of the dipyrrindione
scaffold, which is found in several heme metabolites, is investigated
in heteroleptic palladium(II) complexes. The bis(aqua) complex undergoes
a deprotonation-driven dimerization to form a hydroxo-bridged binuclear
species. Crystallographic, electrochemical, and spectroscopic data,
as well as computational analysis, demonstrate that a two-electron
reduction of the binuclear complex leads to a diradical dianion with
spin density delocalized over the two dipyrrindione ligands.
Collapse
Affiliation(s)
- Clayton J Curtis
- Department of Chemistry and Biochemistry, The University of Arizona, 1306 East University Blvd., Tucson, Arizona 85721, United States
| | - Andrei V Astashkin
- Department of Chemistry and Biochemistry, The University of Arizona, 1306 East University Blvd., Tucson, Arizona 85721, United States
| | - Jeanet Conradie
- Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein 9300, Republic of South Africa.,Department of Chemistry, UiT - The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Abhik Ghosh
- Department of Chemistry, UiT - The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Elisa Tomat
- Department of Chemistry and Biochemistry, The University of Arizona, 1306 East University Blvd., Tucson, Arizona 85721, United States
| |
Collapse
|
7
|
Yamashita KI, Nakajima K, Honda Y, Ogawa T. Facile Redox-Induced Aromatic-Antiaromatic Interconversion of a β-Tetracyano-21,23-Dithiaporphyrin under Ambient Conditions. Chemistry 2020; 26:3633-3640. [PMID: 31880373 DOI: 10.1002/chem.201905823] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Indexed: 01/12/2023]
Abstract
Facile redox-induced aromatic-antiaromatic interconversions were accomplished by using β-tetracyano-21,23-dithiaporphyrin (CN4 S2 Por). Introduced cyano groups not only increased the reduction potential of the porphyrin core but also stabilized the antiaromatic isophlorin (CN4 S2 Iph) by π conjugation. The reduction of CN4 S2 Por with hydrazine in polar solvents quantitatively affords CN4 S2 Iph, even under ambient conditions. CN4 S2 Iph retains a nearly planar conformation and exhibits considerable antiaromaticity. Aerobic oxidation of CN4 S2 Iph to CN4 S2 Por occurs in nonpolar solvents. This study was conducted to contribute to the understanding of the structure-antiaromaticity relationship.
Collapse
Affiliation(s)
- Ken-Ichi Yamashita
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Kana Nakajima
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Yusuke Honda
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Takuji Ogawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| |
Collapse
|