MOLECULAR-ORBITAL STUDY OF LITHIUM ION ASSOCIATION WITH BASES .1. CARBONYL BASES R2CO

Ab initio SCF calculations have been performed to determine the relative lithium ion affinities of the carbonyl bases R2CO and the structures of the complexes R2COLi+. The predicted order of lithium ion affinity for the bases R2CO with respect to R is NH2 > CH3 > OH > H > F. Except for (OH)2COLi+ which has Ca, symmetry, the complexes R2COLi+ have C2v symmetry, with the lithium ion located on the symmetry axis near the oxygen. The major structural changes in the intramolecular coordinates of the bases which occur upon lithium ion complexation include an increase in the carbonyl CO bond length, a decrease in the length of the bond from the carbonyl carbon to the substituent atom X, and an increase in the XCX angle at the carbonyl carbon. The energetic, structural, and electronic properties of the complexes indicate that the interaction between the lithium ion and a carbonyl base is predominantly an ion-dipole attraction rather than a covalent interaction. © 1979.