On the Performance of Second-Order Polarization Propagator Methods in the Calculation of and NMR Spin-Spin Coupling Constants.

This study evaluates the performance of doubles-corrected random phase approximation (RPA) and higher random phase approximation (HRPA) approaches in predicting nuclear magnetic resonance (NMR) coupling constants involving fluorine. Their performance is benchmarked against experimental data and compared with that of higher-level theoretical methods, specifically second-order polarization propagator (SOPPA) and SOPPA(CCSD). Additionally, we discuss their performance relative to density functional theory (DFT).

Morphology of lithium halides in tetrahydrofuran from molecular dynamics with machine learning potentials.

The preferred structures of lithium halides (LiX, with X = Cl, Br, I) in organic solvents have been the subject of a wide scientific debate, and a large variety of forms has been isolated and characterized by X-ray diffraction. The identified molecular scaffolds for LiX are diverse, often built on (LiX) rings with a prevalence of rhomboidal arrangements and an appropriate number of solvent or Lewis base molecules coordinating the lithium ions. Much less is known about the structures of LiX in solution, limiting the understanding of the synergistic role of LiX in reactions with various organometallic complexes, as prominently represented by the turbo Grignard reaction.

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 CHMgCl, as model constituents of the turbo Grignard reagent. LiCl aggregates as LiCl, which preferentially assumes compact cubane-like conformations. In particular, an open-edge pseudotetrahedral frame is promoted by solvent-assisted Li-Cl bond cleavage.

On the Unexpected Accuracy of the M06L Functional in the Calculation of Spin-Spin Coupling Constants.

One-bond spin-spin coupling constants (SSCCs) between F and C are computed with density functional theory (DFT). Surprisingly, M06L stands out for its striking accuracy, outperforming any other investigated functional, including PBE0, otherwise considered one of the most reliable for couplings involving F. Although the computation of nuclear magnetic resonance (NMR) parameters involving F is known to be a challenging task, even with a rather small basis set as pcJ-1, M06L provides results with a MAD = 11.