Gomberg's dimer is the organic compound with the formula Ph₂C=C₆H₅-CPh₃, where Ph = C₆H₅. It is a yellow solid that is air-stable for hours at room temperature and soluble in organic solvents. The compound achieved fame as the dimer of

triphenylmethyl radical The triphenylmethyl radical (often shortened to trityl radical after 1927 suggestion by Burckhardt Helferich, Helferich et al.) is an organic compound with the formula (C6H5)3C. It is a persistent radical. It was the first radical (chemistry), rad ...

, which was prepared by Moses Gomberg in his quest for hexaphenylethane. Its quinoid structure has been determined by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

. The C-C bond that reversibly breaks is rather long at 159.7

picometer The picometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer ( American spelling) is a unit of length in the International System of Units (SI), equal to , or one trillionth o ...

Synthesis and reactions

Gomberg's dimer can be prepared quantitatively by treating trityl bromide with powdered copper or silver: :2Ph₃CBr + 2Cu → Ph₂C=C₆H₅-CPh₃ + 2CuBr Gomberg's dimer reversibly dissociates to the

in organic solvents: : Gomberg dimer dissociation

References

{{reflist Aromatic hydrocarbons

Synthesis and reactions

See also

References