Gomberg's dimer

Gomberg's dimer
Names
Preferred IUPAC name
1,1′,1′′-{[4-(Diphenylmethylidene)cyclohexa-2,5-dien-1-yl]methanetriyl}tribenzene
Other names
3-triphenylmethyl-6-diphenylmethylidene-1,4-cyclohexadiene
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/C38H30/c1-6-16-30(17-7-1)37(31-18-8-2-9-19-31)32-26-28-36(29-27-32)38(33-20-10-3-11-21-33,34-22-12-4-13-23-34)35-24-14-5-15-25-35/h1-29,36H
    Key: FWSYACUVHKGULL-UHFFFAOYSA-N
  • C1=CC=C(C=C1)C(=C2C=CC(C=C2)C(C3=CC=CC=C3)(C4=CC=CC=C4)C5=CC=CC=C5)C6=CC=CC=C6
Properties
C38H30
Molar mass 486.658 g·mol−1
Appearance Yellow solid
Density 1.16 g/cm3
Melting point 140–144 °C; 284–291 °F; 413–417 K
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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, which was prepared by Moses Gomberg in his quest for hexaphenylethane.

Its quinoid structure has been determined by X-ray crystallography. The C-C bond that reversibly breaks is rather long at 159.7 picometers.

Synthesis and reactions

Gomberg's dimer can be prepared quantitatively by treating trityl bromide with powdered copper or silver:

2 Ph3CBr + 2 Cu → Ph2C=C6H5-CPh3 + 2 CuBr

Gomberg's dimer reversibly dissociates to the triphenylmethyl radical in organic solvents:

See also

References

  1. 1 2 Bochkarev, L. N.; Molosnova, N. E.; Zakharov, L. N.; Fukin, G. K.; Yanovsky, A. I.; Struchkov, Y. T. (1995). "1-Diphenylmethylene-4-(triphenylmethyl)cyclohexa-2,5-diene Benzene Solvate". Acta Crystallographica Section C Crystal Structure Communications. 51 (3): 489–491. doi:10.1107/S0108270194009005.
  2. ↑ Eisenberg, David C.; Lawrie, Christophe J. C.; Moody, Anne E.; Norton, Jack R. (1991). "Relative Rates of Hydrogen Atom (H.) Transfer from Transition-Metal Hydrides to Trityl Radicals". Journal of the American Chemical Society. 113 (13): 4888–4895. doi:10.1021/ja00013a026.
  3. ↑ Pangia, Thomas M.; Davies, Casey G.; Prendergast, Joshua R.; Gordon, Jesse B.; Siegler, Maxime A.; Jameson, Guy N. L.; Goldberg, David P. (28 March 2018). "Observation of Radical Rebound in a Mononuclear Nonheme Iron Model Complex". Journal of the American Chemical Society. 140 (12): 4191–4194. doi:10.1021/jacs.7b12707. PMC 6047074. PMID 29537258.