“The effect of solvent on the structure of the transition state for the SN2 reaction between cyanide ion and ethyl chloride in DMSO and THF probed with six different kinetic isotope effects” Yao-ren Fang, Susanna MacMillar, Jonas Eriksson, Magdalena Kołodziejska-Huben, Agnieszka Dybała-Defratyka, Piotr Paneth, Olle Matsson, and Kenneth Charles Westaway J. Org. Chem. 71, 4742-4747 (2006)