Date
2023-05-12Author
Guthardt, RobinJacob, Hannes LukasHerle, DominicLeibold, MichaelBruhn, ClemensHeinz, MyronHolthausen, Max C.Siemeling, UlrichMetadata
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Aufsatz
Ferrocene-Based N-Heterocyclic Plumbylenes [Fe{(η⁵- C₅H₄)NSiMe₂R}₂Pb:]: Influence of the Steric Demand of the NSubstituents on Their Dimerization via C-H Activation with Pbᴵᴵ
Abstract
Ferrocene-based N-heterocyclic plumbylenes fc[(NSiMe₂R)₂Pb:] (1; fc=1,1’-ferrocenylene) are easily accessible by transamination from [(Me₃Si)₂N]₂Pb and the corresponding 1,1’-diaminoferrocene derivatives fc(NHSiMe₂R)₂. They may form unconventional dimers 2 by a process, which causes the cleavage of a cyclopentadienyl C−H bond and the formation of a Pb−C and an N−H bond. The monomer-dimer equilibrium (2 1⇆2) has been addressed experimentally and computationally. It critically depends on the steric demand of the N-substituents SiMe₂R, which has been varied systematically by using homologues with aliphatic (R=methyl, ethyl, isopropyl, tert-butyl) and aromatic units (R=phenyl, mesityl, ferrocenyl). Even in the sterically least congested case (R=methyl), dimerization is only slightly exergonic. It eventually becomes prohibitively endergonic with increasingly larger substituents and is thus not observed for R=tert-butyl, mesityl, and ferrocenyl. R=phenyl represents a borderline case, where the dimer is still detectable in the equilibrium mixture, albeit as a very minor component, in accord with the slightly endergonic Gibbs free energy change calculated for its formation. Addition of 4-dimethylaminopyridine (DMAP) to the monomer-dimer equilibrium mixtures cleanly affords the corresponding adducts [1(DMAP)], irrespective of the equilibrium composition.
Citation
In: Chemistry - An Asian Journal Volume 18 / Issue 13 (2023-05-12) eissn:1861-471XSponsorship
Gefördert im Rahmen des Projekts DEALCitation
@article{doi:10.17170/kobra-202307248470,
author={Guthardt, Robin and Jacob, Hannes Lukas and Herle, Dominic and Leibold, Michael and Bruhn, Clemens and Heinz, Myron and Holthausen, Max C. and Siemeling, Ulrich},
title={Ferrocene-Based N-Heterocyclic Plumbylenes [Fe{(η⁵- C₅H₄)NSiMe₂R}₂Pb:]: Influence of the Steric Demand of the NSubstituents on Their Dimerization via C-H Activation with Pbᴵᴵ},
journal={Chemistry - An Asian Journal},
year={2023}
}
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2023-07-24T15:24:07Z 2023-07-24T15:24:07Z 2023-05-12 doi:10.17170/kobra-202307248470 http://hdl.handle.net/123456789/14922 Gefördert im Rahmen des Projekts DEAL eng Namensnennung 4.0 International http://creativecommons.org/licenses/by/4.0/ carbene homologues lead metallocenes steric hindrance subvalent compounds 540 Ferrocene-Based N-Heterocyclic Plumbylenes [Fe{(η⁵- C₅H₄)NSiMe₂R}₂Pb:]: Influence of the Steric Demand of the NSubstituents on Their Dimerization via C-H Activation with Pbᴵᴵ Aufsatz Ferrocene-based N-heterocyclic plumbylenes fc[(NSiMe₂R)₂Pb:] (1; fc=1,1’-ferrocenylene) are easily accessible by transamination from [(Me₃Si)₂N]₂Pb and the corresponding 1,1’-diaminoferrocene derivatives fc(NHSiMe₂R)₂. They may form unconventional dimers 2 by a process, which causes the cleavage of a cyclopentadienyl C−H bond and the formation of a Pb−C and an N−H bond. The monomer-dimer equilibrium (2 1⇆2) has been addressed experimentally and computationally. It critically depends on the steric demand of the N-substituents SiMe₂R, which has been varied systematically by using homologues with aliphatic (R=methyl, ethyl, isopropyl, tert-butyl) and aromatic units (R=phenyl, mesityl, ferrocenyl). Even in the sterically least congested case (R=methyl), dimerization is only slightly exergonic. It eventually becomes prohibitively endergonic with increasingly larger substituents and is thus not observed for R=tert-butyl, mesityl, and ferrocenyl. R=phenyl represents a borderline case, where the dimer is still detectable in the equilibrium mixture, albeit as a very minor component, in accord with the slightly endergonic Gibbs free energy change calculated for its formation. Addition of 4-dimethylaminopyridine (DMAP) to the monomer-dimer equilibrium mixtures cleanly affords the corresponding adducts [1(DMAP)], irrespective of the equilibrium composition. open access Guthardt, Robin Jacob, Hannes Lukas Herle, Dominic Leibold, Michael Bruhn, Clemens Heinz, Myron Holthausen, Max C. Siemeling, Ulrich 9 Seiten doi:10.1002/asia.202300266 Blei Carbenkomplexe Metallocene Sterische Hinderung publishedVersion eissn:1861-471X Issue 13 Chemistry - An Asian Journal Volume 18 false e202300266
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