6533b7dcfe1ef96bd1271e03

RESEARCH PRODUCT

Theoretical and structural studies of lithium cyclic amide conformations. Monomers and aggregates

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description

High level ab initio calculations on the conformations of unsolvated and solvated lithium piperidide, 1, and lithium morpholide, 2, were carried out. It was found that both monomers exhibit a global minimum for a chair structure with a planar nitrogen, and 2 shows an additional stable pseudo boat conformation. Dimers and amine–lithium amide mixed aggregates were also calculated including discrete solvation; the role of aggregation is clearly shown both by the changes in geometries and in the stabilization energies. Semiempirical calculations carried out on a recently synthesized tetrameric mixed aggregate give a geometry very similar to the structure determined by X-ray diffraction. The present calculations very usefully confirm the likelihood of mixed aggregates of morpholine–lithium morpholide predicted by the carbonylation reactions and not attainable in solid forms.