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Do dihydroxymagnesium carboxylates form Grignard-type reagents? A theoretical investigation on decarboxylative fragmentation.

J. Mol. Model. 24:106 (2018)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
Dihydroxymagnesium carboxylates [(OH)MgOCR] were probed for decarboxylation on a theoretical level, by utilizing both Møller-Plesset perturbation theory (MP2) and density functional theory (B3LYP-DFT) computations. This study is connected to the question of whether this recently introduced, astrobiologically relevant chemical class may form Grignard-type reagent molecules. To extract trends for a broad molecular mass range, different linear alkyl chain lengths between Cand Cwere computed. The forward energy barrier for decarboxylation reactions increases linearly as a function of the ligand's chain length. Decarboxylation-type fragmentations of these organomagnesium compounds seem to be improbable in non-catalytic, low energetic environments. A high forward energy barrier (E > 55 kcal mol) towards a described transition state restricts the release of CO. Nevertheless, we propose the release of COon a theoretical level, as been revealed via an intramolecular nucleophilic attack mechanism. Once the challenging transition state for decarboxylation is overcome, a stable Mg-C bond is formed. These mechanistic insights were gained by help of natural bond orbital analysis. The Cα atom (first carbon atom in the ligand chain attached to the carboxyl group) is thought to prefer binding towards the electrophilic magnesium coordination center, rather than towards the electrophilic CO-carbon atom. Additionally, the putatively formed Grignard-type OH-bearing product molecules possess a more polarized Mg-C bond in comparison to RMgCl species. Therefore, carbanion formation from OH-bearing Grignard-type molecules is made feasible for triggering C-C bond formation reactions. Graphical abstract This study asks whether recently introduced, astrobiologically dihydroxymagnesium carboxylates form Grignard-type reagent molecules via decarboxylative fragmentation.
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Publication type Article: Journal article
Document type Scientific Article
Keywords Organometallics ; Astrochemistry ; Organomagnesium Molecules ; Grignard Reagent ; Dft ; Mp2 ; Nbo
Language english
Publication Year 2018
HGF-reported in Year 2018
ISSN (print) / ISBN 1610-2940
e-ISSN 0948-5023
Quellenangaben Volume: 24, Issue: 4, Pages: , Article Number: 106 Supplement: ,
Publisher Springer
Reviewing status Peer reviewed
POF-Topic(s) 30202 - Environmental Health
Research field(s) Environmental Sciences
PSP Element(s) G-504800-001
Scopus ID 85044588163
PubMed ID 29589173
Erfassungsdatum 2018-05-25