Basicity of a stable carbene, 1,3-di-tert-butylimidazol-2-ylidene, in THF.
The basicity of 1,3-di-tert-butylimidazol-2-ylidene (1) was measured in THF against three hydrocarbon indicators. Both ion pairs and free ions were found and the corresponding equilibrium constants were measured. Homoconjugation was not found in either THF or DMSO. The carbene is effectively more basic in DMSO by several pK units, probably because of hydrogen bonding of 1-H(+) to DMSO. Model ab initio computations are consistent with these results.
Kim
Yeong-Joon
YJ
Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
Streitwieser
Andrew
A