Ab Initio MO Calculations of NMR 15N–6Li Coupling Constants in Lithium Amide Monomers, Oligomers, and Mixed Aggregates with LiCl

The NMR 15N–6Li coupling constants 1JNLi in LiNH2 and LiN(CH3)2 monomers and their oligomers and mixed aggregates with LiCl were calculated using ab initio self-consistent perturbation theory and the relation between the molecular structure and 1JNLi values was examined. The calculated 1JNLi values in the monomers are influenced by solvation and agree well with experimetal values when model solvent molecules are coordinated at the lithium atom. The calculated 1JNLi values in cyclic oligomers also agree well with experiment and support the structures derived from NMR experiments in solution. For the mixed trimer, (LiNH2)2LiCl, a ladder form was obtained as the most stable structure when the lithium atoms are solvated by two H2O or two NH3 molecules.