Morphological Plasticity of LiCl Clusters Interacting with Grignard Reagent in Tetrahydrofuran.

Ab initio molecular dynamics simulations are used to explore tetrahydrofuran (THF) solutions containing pure LiCl and LiCl with CH 3 MgCl, as model constituents of the turbo Grignard reagent. LiCl aggregates as Li 4 Cl 4 , which preferentially assumes compact cubane-like conformations. In particular, an open-edge pseudotetrahedral frame is promoted by solvent-assisted Li-Cl bond cleavage. Among the Grignard species involved in the Schlenk equilibrium, LiCl prefers to coordinate MgCl 2 through μ 2 -Cl bridges. Using a 1:1 Li:Mg ratio, the plastic tetranuclear LiCl cluster decomposes to a highly solvated mixed LiCl·MgCl 2 aggregate with prevalent Li-(μ 2 -Cl) 2 -Mg rings and linear LiCl entities. The MgCl 2 -assisted disaggregation of Li 4 Cl 4 occurs through transient structures analogous to those detected for pure LiCl in THF, also corresponding to moieties observed in the solid state. This study identifies a synergistic role of LiCl for the determination of the compounds present in turbo Grignard solutions. LiCl shifts the Schlenk equilibrium promoting a higher concentration of dialkylmagnesium, while decomposing into smaller, more soluble, mixed Li:Mg:Cl clusters.