Structural nonrigidity of 9,9,10-trimethyland 4,5,9,9,10-pentamethylphenanthrenylium ions
摘要:
DFT quantum-chemical calculations predicted structural nonrigidity of 9,9,10-trimethyl- and 4,5,9,9,10-pentamethylphenanthrenylium ions. The cross section of the potential energy surface at the nonrigidity coordinate for the first of these ions is symmetric, and for the second, asymmetric. These results were confirmed experimentally: the C-13 NMR spectra of 4,5,9,9,10-pentamethylphenanthrenylium showed considerable temperature dependence of chemical shifts which is not typical of 9,9,10-trimethylphenanthrenylium.