text: Various extreme cases have been identified where the C-C bond is elongated.  In Gomberg's dimer, one C-C bond is rather long at 159.7 picometers.  It is this bond that reversibly and readily breaks at room temperature in solution:
  In the even more congested molecule hexakis(3,5-di-tert-butylphenyl)ethane, the bond dissociation energy to form the stabilized triarylmethyl radical is only 8 kcal/mol. Also a consequence of its severe steric congestion, hexakis(3,5-di-tert-butylphenyl)ethane has a greatly elongated central bond with a length of 167 pm.