VAg reactivity indices (ß) measured for naphthalene, anthracene, 1,2-benzanthracene, naphthacene, 1,2,5,6-dibenzanthracene, pentacene, and/or certain derivatives vary by six orders of magnitude in benzene at 25°. An orbital correlation through the transition state is presented for anthracene as a model acceptor in an attempt to identify those acceptor properties which contribute to the activation energy for O^Ag addition insofar as this largely controls acceptor reactivity. It is shown that the x-relocalization energy provides a satisfactory reactivity parameter for unsubstituted acceptors if this is estimated as the difference in x-electron energy of the acceptor and of those odd-alternant fragments which provide electron localization at the site of CVAg addition, with a value of -36 kcal for the bond integral. Electron donating substituents at the site of (VAg addition increase acceptor reactivity in the order H < C6H5 < CH30 ~CH3, each methyl substituent producing an increase in reactivity by a factor of *~13 for anthracene.

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Is the intensity of the high overtones you see caused by the electrical anharmonicity of the bonds being stretched? B. R. Henry. We have actually looked on the problem more from the point of view of mechanical anharmonicity than of electrical anharmonicity, but in this region of the spectrum it may be impossible to disentangle one from the other. The detailed intensity problem in normal mode language is one that I think we haven't solved, and to my knowledge, neither has anyone else. S. J. STRICKLER. I do not believe you can say the results are all due to electrical anharmonicity. The local mode states are just those for which the mechanical anharmonicity is a maximum. One can think of anharmonicity in terms of a sort of Morse potential-the lower the dissociation energy, the greater the anharmonicity. For a CH2 group, for example, the Morse curve for a symmetric CH stretch would level