ORGN 313 |
| Lawrence M. Pratt1, Donald G Truhlar2, Christopher J Cramer3, and Jason D. Thompson2. (1) Department of Chemistry, Fisk University, 1000 17th Ave. N, Nashville, TN 37211, (2) Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455-0431, (3) Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455-0431 |
| Several NMR studies have determined the aggregation states of lithium dialkylamides in hydrocarbon and ethereal solvents. The results depend on the solvent and the nature of the alkyl ligand. In pentane, trimers and tetramers are common aggregates, whereas in THF, dimers often predominate. Very hindered lithium amides are monomeric or exist as a monomer-dimer mixtures in THF. In the present study, hybrid DFT was used to calculate the effects of solvation and steric effects on the aggregation state and to compare different solvation models. These models include microsolvation by THF ligands and by methyl ligands, which are computationally less demanding. Continuum solvation was also used in conjunction with the microsolvation model. The results were compared for the relatively unhindered lithium dimethylamide, which is mostly dimeric in THF, and lithium tetramethylpiperidide, which exists as an equilibrium mixture of monomers and dimers in THF. |
|
Physical Organic, Combinatorial, Materials, Molecular Recognition
8:00 PM-10:00 PM, Tuesday, March 30, 2004 Anaheim Convention Center -- Hall A, Poster
Sci-Mix
Division of Organic Chemistry |