Structural and solution calorimetric studies of sulfur binding to nucleophilic carbenes

The enthalpy of sulfur atom transfer to stable cyclic carbenes has been mea sured by solution calorimetry. Absolute values of the R2C=S bond strengths (approximate to 100 kcal/mol) are in a range comparable to those of R3P=S b ond strengths. These data are compared to reported enthalpies of binding of carbenes and phosphines to metal complexes. Similar patterns of donor abil ities are displayed for both oxidative addition of sulfur and binding to me tal complexes.