Influence of the correlation,aggregation, and solvation on ab initio computed Li-C,Li-N,and Li-Li NMR coupling constants

The (1)J and (3)J(C-Li), (1)J(N-Li), and (2)J(Li-Li) NMR coupling constants have been calculated for various homogeneous and heterogeneous aggregates of methyllithium and lithium dimethylamide at the HF and MP2 levels of calculation. Ethereal solvation has also been taken into account either through a continuum model or through the explicit introduction of Me(2)O molecules. The results obtained are in good general agreement with the experimental data available for methyllithium itself or model alkyllithiums and supports the empirical rule proposed by Bauer, Winchester, and Schleyer to evaluate (1)J(C-Li) provided that calculations include solvent and/or aggregation effects.