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Petrov A, Wellnitz T, Hennersdorf F, Reiß F, Hering-Junghans C. On Haptotropic Rearrangements of Diphosphene and Diarsene Ligands in Titanium Complexes. Chemistry 2024; 30:e202400575. [PMID: 38391154 DOI: 10.1002/chem.202400575] [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: 02/21/2024] [Revised: 02/23/2024] [Accepted: 02/23/2024] [Indexed: 02/24/2024]
Abstract
Dipnictenes of the type RE=ER (E=P, As, Sb, Bi) are the isovalence electronic heavier analogs of alkenes. Although diphosphenes and dipnictenes in general show a variety of binding modes in metal complexes, little is known about haptotropic shift reactions involving these ligands. Herein, we report an unprecedented η2 to η1 rearrangement of the dipnictene ligands in titanocene complexes of the type Cp2Ti(Pn2Ar2) (Pn=P, As; Ar=2,4,6-Me3-C6H2, Mes; 2,6-iPr2-C6H3, Dip; 2,4,6-iPr3-C6H2, Tip), initiated by Lewis basic ligands (L=MeCN, PMe3, AdNC, CO). In the presence of L the dipnictene ligand changes its hapticity from η2 to η1 and complexes of the general form Cp2Ti(L)(Pn2Ar2) with a succinctly different electronic structure are obtained. Electronically, the new complexes are best described as biradicaloids with antiferromagnetically coupled (via a π-bond) [Cp2TiIII]⋅+ and [Pn2Ar2]⋅- fragments. However, the biradical character of these systems is affected by the electronic features of the co-ligand and significantly decreases moving from PMe3/MeCN (σ-donors) to CNAd/CO (σ-donors/π-acceptors).
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Affiliation(s)
- Andrey Petrov
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Straße 3a, 18059, Rostock, Germany
| | - Tim Wellnitz
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Straße 3a, 18059, Rostock, Germany
- Current address: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | | | - Fabian Reiß
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Straße 3a, 18059, Rostock, Germany
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Yin L, Liu W. Stable oganocopper(III) complexes generated via oxidative addition. Sci Bull (Beijing) 2024; 69:288-289. [PMID: 38105160 DOI: 10.1016/j.scib.2023.12.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Affiliation(s)
- Lingfeng Yin
- Department of Chemistry, University of Cincinnati, Cincinnati OH 45221, USA
| | - Wei Liu
- Department of Chemistry, University of Cincinnati, Cincinnati OH 45221, USA.
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Yan W, Carter S, Hsieh CT, Krause JA, Cheng MJ, Zhang S, Liu W. Copper-Carbon Homolysis Competes with Reductive Elimination in Well-Defined Copper(III) Complexes. J Am Chem Soc 2023; 145:26152-26159. [PMID: 37992224 DOI: 10.1021/jacs.3c08510] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2023]
Abstract
Despite the recent advancements of Cu catalysis for the cross-coupling of alkyl electrophiles and the frequently proposed involvement of alkyl-Cu(III) complexes in such reactions, little is known about the reactivity of these high-valent complexes. Specifically, although the reversible interconversion between an alkyl-CuIII complex and an alkyl radical/CuII pair has been frequently proposed in Cu catalysis, direct observation of such steps in well-defined CuIII complexes remains elusive. In this study, we report the synthesis and investigation of alkyl-CuIII complexes, which exclusively undergo a Cu-C homolysis pathway to generate alkyl radicals and CuII species. Kinetic studies suggest a bond dissociation energy of 28.6 kcal/mol for the CuIII-C bonds. Moreover, these four-coordinate complexes could be converted to a solvated alkyl-CuIII-(CF3)2, which undergoes highly efficient C-CF3 bond-forming reductive elimination even at low temperatures (-4 °C). These results provide strong support for the reversible recombination of alkyl radicals with CuII to form alkyl-CuIII species, an elusive step that has been proposed in Cu-catalyzed mechanisms. Furthermore, our work has demonstrated that the reactivity of CuIII complexes could be significantly influenced by subtle changes in the coordination environment. Lastly, the observation of the highly reactive neutral alkyl-CuIII-(CF3)2 species (or with weakly bound solvent molecules) suggests they might be the true intermediates in many Cu-catalyzed trifluoromethylation reactions.
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Affiliation(s)
- Wenhao Yan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Samantha Carter
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Chi-Tien Hsieh
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
| | - Jeanette A Krause
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Mu-Jeng Cheng
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
| | - Shiyu Zhang
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Wei Liu
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
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Nguyen BX, VandeVen W, MacNeil GA, Zhou W, Paterson AR, Walsby CJ, Chiang L. High-Valent Ni and Cu Complexes of a Tetraanionic Bis(amidateanilido) Ligand. Inorg Chem 2023; 62:15180-15194. [PMID: 37676794 DOI: 10.1021/acs.inorgchem.3c02358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
High-valent metal species are often invoked as intermediates during enzymatic and synthetic catalytic cycles. Anionic donors are often required to stabilize such high-valent states by forming strong bonds with the Lewis acidic metal centers while decreasing their oxidation potentials. In this report, we discuss the synthesis of two high-valent metal complexes [ML]+ in which the NiIII and CuIII centers are ligated by a new tetradentate, tetraanionic bis(amidateanilido) ligand. [ML]+, obtained via chemical oxidation of ML, exhibits UV-vis-NIR, EPR, and XANES spectra characteristic of square planar, high-valent MIII species, suggesting the locus of oxidation for both [ML]+ is predominantly metal-based. This is supported by theoretical analyses, which also support the observed visible transitions as ligand-to-metal charge transfer transitions characteristic of square planar, high-valent MIII species. Notably, [ML]+ can also be obtained via O2 oxidation of ML due to its remarkably negative oxidation potentials (CuL/[CuL]+: -1.16 V, NiL/[NiL]+: -1.01 V vs Fc/Fc+ in MeCN). This demonstrates the exceptionally strong donating nature of the tetraanionic bis(amidateanilido) ligation and its ability to stabilize high-valent metal centers..
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Affiliation(s)
- Bach X Nguyen
- Department of Chemistry, University of the Fraser Valley, Abbotsford, British Columbia V2S 7M8, Canada
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Warren VandeVen
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Gregory A MacNeil
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Wen Zhou
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Alisa R Paterson
- Canadian Light Source, 44 Innovation Boulevard, Saskatoon, Saskatchewan S7N 2 V3, Canada
| | - Charles J Walsby
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Linus Chiang
- Department of Chemistry, University of the Fraser Valley, Abbotsford, British Columbia V2S 7M8, Canada
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Eichelmann R, Ballmann J, Gade LH. Tetraazacoronenes and Their Dimers, Trimers and Tetramers. Angew Chem Int Ed Engl 2023; 62:e202309198. [PMID: 37409960 DOI: 10.1002/anie.202309198] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 07/05/2023] [Accepted: 07/06/2023] [Indexed: 07/07/2023]
Abstract
Tetraazacoronenes were synthesized from bay-functionalized tetraazaperylenes by Zr-mediated cyclization and four-fold Suzuki-Miyaura cross coupling. In the Zr-mediated approach, an η4 -cyclobutadiene-zirconium(IV) complex was isolated as an intermediate to cyclobutene-annulated derivatives. Using bis(pinacolatoboryl)vinyltrimethylsilane as a C2 building block gave the tetraazacoronene target compound along with the condensed azacoronene dimer as well as higher oligomers. The series of extended azacoronenes show highly resolved UV/Vis absorption bands with increased extinction coefficients for the extended aromatic cores and fluorescence quantum yields of up to 80 % at 659 nm.
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Affiliation(s)
- Robert Eichelmann
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Joachim Ballmann
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Lutz H Gade
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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