Electron affinity and substituent effects in radical anions

The first vertical electron affinities EA of 13 series of molecules and free radicals D(X-i)(n) are related to the inductive (sigma(I)), resonance (sigma(R)), and polarization (sigma(alpha)) parameters of substituents X-i by the dependences EA = EA(H) + a Sigma sigma(I) + b Sigma sigma(R) + c Sigma sigma(alpha). In radical anions D+.(X-i)(n), compared to radical cations D+.(X-i)(n), the polarization interaction is weaker or similar in magnitude but has an opposite sign. The previously unknown resonance parameters sigma(R) of substituents SiMe3 and CH2SiMe3 bound to the radical anion center R H2C=CH-. were calculated.