Effect of substituents on the first ionization potentials of aromatic and heteroaromatic compounds. The sigma(+)(R) resonance parameters of Si-, Ge-,Sn-, and Pb-containing fragments

The first vertical ionization potentials (IP) of monosubstituted benzenes, hexafluorobenzenes, naphthalenes, anthracenes, furans, thiophenes, and sele nophenes and the second IP of monosubstituted tellurophenes are related to the inductive, resonance, and polarization parameters of substituents by de pendences of the type IP = a + b sigma(I) + c sigma(R) + d sigma(alpha). Th e contribution of polarizability effect, d sigma(alpha), to the IP value is determined by the degree of delocalization of the positive charge in radic al cations formed upon photoionization of the compounds studied. The sigma( R)(+) resonance parameters of nineteen Si-, Ge-, Sn-, and Pb-containing sub stituents in naphthalene, furan, and thiophene series were calculated.