Open AccessQuantum Chemical Investigation of Dimerization in the Schlenk Equilibrium of Thiophene Grignard Reagents
Author(s) -
Ethan R. Curtis,
Matthew D. Hannigan,
A. Vítek,
Paul M. Zimmerman
Publication year - 2020
Publication title -
the journal of physical chemistry. a/the journal of physical chemistry. a.
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.756
H-Index - 235
eISSN - 1520-5215
pISSN - 1089-5639
DOI - 10.1021/acs.jpca.9b09985
Subject(s) - chemistry , thiophene , aryl , reactivity (psychology) , ligand (biochemistry) , monomer , reagent , computational chemistry , organic chemistry , polymer , medicine , biochemistry , alkyl , alternative medicine , receptor , pathology
The Schlenk equilibrium of Grignard reagents describes the intricate relationships between monomers, aggregates, and exchange products. The core step of the Schlenk equilibrium, formally 2RMgX ⇌ R 2 Mg + MgX 2 , has been subject to computational studies of simple methyl Grignards and NMR determination of thermodynamics. These studies neglect the effect the R group may have on the accessibility of intermediates in the Schlenk equilibrium. In this study, computational reaction discovery tools were employed to thoroughly search the chemical space for feasible dimerizations and pathways to ligand exchange for thiophene Grignards. Three bridged dimers, μ-(Cl, C), μ-(Cl, Cl), and μ-Cl, were found to be vital intermediates, which are stabilized by π-interactions involving the thiophene group. These dimers are approximately as thermodynamically stable as the Grignard monomers and its ligand exchange products, and therefore, their reactivity should be considered when examining mechanisms for aryl Grignard or cross-coupling reactions.