1. Grellman, K-H., Sherman, G. M., and Linschitz, H., J. Amer. Chem. Soc., 85, 1881 (1963); Linschitz, H., and Grellman, K-H., 86, 303 (1964). Bowen, E. J., and Eland, J. H. D., Proc. Chem. Soc., 202 (1963).
2. Walling, C., Free Radicals in Solution, 522 (John Wiley and Sons, London, 1957).
3. Cottrell, T. L., The Strengths of Chemical Bonds, Second ed., 203 (Butter-worths, London, 1958). Mortimer, C. T., Reaction Heats and Bond Strengths, 139 (Pergamon Press, London, 1962).
4. see for example, ref. 2, pp. 481, 522.
5. Lyons, W. E., Nature, 162, 1004 (1948).