Michelle Coote

Computer Aided Chemical Design

JACs Image Challenge

Sep 2011

Isse A. A., Gennaro A., Lin C. Y., Hodgson J. L., Coote M.L., Tamaz G. Mechanism of Carbon-Halogen Bond Reductive Cleavage in Activated Alkyl Amine Halide Initiators Relevant to Living Radical Polymerization" Theoretical and Expeirmental Study. J. Am. Chem. Soc. (2011), 113, 6254-6264. http://dx.doi.org/10.1021/ja110538b

The mechanism of dissociation of radical anions RX-, arising from one-electron reduction of RX, can be classified as being either (I) homolytic or (II) heterolytic or neither (III). This work shows that injection of an electron into an alkyl halide follows a concerted dissociative electron transfer mechanism resulting in the formation of a weak adduct between R. and X- rather than a stable RX-. The image below shows the singly occupied molecular orbital (SOMO) and total energy of the RX- radical anion as a function of the R-X distance following injection of an electron into R-X. In terms of the homolytic vs. heterolytic nomenclature how would you classify the mechanism of dissociative electron transfer of carbon-halogen bonds in alkyl halides?

(A) Homolytic (case I)

(B) Heterolytic (case II)

(C) Cannot be classified as either homolytic or heterolytic (case III)

Check your answer here!