| Abstract
| - Computations are reported at the HF/6-31+g* level for ion pair SN2 reactions of methyl, ethyl, n-propyl,isopropyl, and allyl halides with LiX·E, LiX·2E, and LiX·3E (X = F, Cl, Br; E = dimethyl ether as amodel for THF). Some calculations were also done at the MP2, B3LYP, and mPW1PW91 levels. Inaddition to normal SN2-type (type I) transition structures (TSs), novel unsymmetrical TSs were found inwhich the Li is coordinated to a single halide. With LiX·2E, such structures are already competitive withthe type I structures, and with LiX·3E, only the type II structures were found. With incorporation ofdielectric solvation, the type II structures are relatively even more stable. The results suggest that suchstructures are better models for ion pair displacement reactions in ethereal solvents.
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