Anisochronous Methylene Protons of Metalloporphyrins Bearing Peripheral Alkyl Groups
Busby, C.A. and David Dolphin
J. Magn. Reson.
The 100 MHz spectra of thallium, lead, and scandium octaethylporphyrins and of a μ-oxo dimer of scandium octaethylporphyrin show the methylene protons, of the ethyl side chains, to be anisochronous. The 100 and 300 MHz H spectra of a thallium etioporphyrin show that the methylene protons of the 4 ethyl side groups of this porphyrin are also anisochronous. It is suggested that these phenomena result from the inherent asymmetry of the metalloporphyrins rather than from hindered rotations of the side chains.