Ab Initio Modeling of Organolithium Equilibria

Abstract

Experimental ion pair pK's of monomeric contact ion pair lithium salts in THF from our previous studies give good correlations with ab initio calculations at the Hartree-Fock 6-31+g(d) level. PCM methods were found to be inadequate in nonpolar organic solvents, and dielectric solvation was not used in the correlations. Specific coordination of two or three ether solvent molecules with lithium was found to be satisfactory. These correlations include carboxamides, amines, dithianes, sulfones, and sulfoxides, as well as some ketones, beta-diketones, and the lithium salts of dianions.

Lithium Choreography: Intramolecular Arylations of Carbamate‐Stabilised Carbanions and Their Mechanisms Probed by In Situ IR Spectroscopy and DFT Calculations

“…Thus, our model (Scheme 13) involves one explicit LDA dimer coordinated to the carbonyl oxygen of the carbamate 2 a (A), a structure corresponding to the pre-lithiated complex indicated by the in situ IR studies. vation in our model, in line with the findings of Streitwieser et al, [41] who found that the integral equation polarisable continuum model (IEPCM) was poor at predicting the solvation energies of a range of organic species in THF, and in the absence of bulk solvation, pK(Li) values for a range of lithium compounds were well predicted. In view of the experimental observation that excess base facilitates the reaction our model has a dimer of LDA coordinated to the carbonyl oxygen atom.…”

The Mechanism of the Stereospecific Intramolecular Arylation of Lithiated Ureas: The Role of Li+ Probed by Electronic Structure Calculations, and by NMR and IR Spectroscopy

“…[31] Thus, we used the B3LYP/6-31++G** optimal structures to determine single-point energies at the M06-2X /6-31++G** level and corrected these to give free energies as before. As far as bulk solvation is concerned, we decided, following the work of Streitwieser and co-workers, [32] to ignore bulk solvation effects. They found that the integral equation polarisable continuum model (IEPCM) was poor at predicting the solvation energies of a range of organic species in THF, whilst with no bulk solvation the pK(Li) values of a range of lithium compounds can be well predicted.…”

Chiral Lithiated Allylic α‐Sulfonyl Carbanions: Experimental and Computational Study of Their Structure, Configurational Stability, and Enantioselective Synthesis

“…However, a similar calculation of the analogous lithiated α‐trifluormethylsulfonyl carbanion [PhC(Me)SO 2 CF 3 ]‐Li ⋅ (OMe 2 ) 2 20 showed a CIP structure of type K with two OLi bonds to be the most stable one. While an initio calculation of [PhC(H)SO 2 Ph]Li ⋅ (OMe 2 ) 2 also gave a structure of type A , that of [PhC(H)SO 2 Ph]Li ⋅ (OMe 2 ) 3 , which carries three ether molecules at the Li atom, gave a structure of type L having no CLi bond 52. A DFT calculation of [MeC(H)SO 2 Ph]Li ⋅ (OMe 2 ) 2 found a structure of type A to be more stable than a structure of type K 35…”