Hexaphenylethane is a hypothetical organic compound consisting of an ethane core with six phenyl substituents. , all attempts at its synthesis have been unsuccessful. The trityl free radical, Ph<sub>3</sub>C, was originally thought to dimerize to form hexaphenylethane. However, an inspection of the NMR spectrum of this dimer reveals that it is in fact a non-symmetrical species, Gomberg's dimer instead.
A substituted derivative of hexaphenylethane, hexakis(3,5-di-t-butylphenyl)ethane, has however been prepared. It features a very long central CâÂÂC bond at 167 pm (compared to the typical bond length of 154 pm). Attractive London dispersion forces between the t-butyl substituents are believed to be responsible for the stability of this very hindered molecule.