Understanding barriers to internal rotation in toluene phenylsilane and their cations

摘要

Abstract: Threshold photoionization spectra of toluene$+$PLU$/ and phenylsilane$+$PLU$/ using the new pulsed field ionization technique resolve internal rotor states. As in the neutral S$-0$/ and S$-1$/ states, sixfold barriers to internal rotation are small in the cations, $LS 25 cm$+$MIN@1$/. Ab initio calculations support a donor-acceptor model that qualitatively explains why all sixfold barriers are small while some threefold barriers are much larger.!24