Tridentate Ligand Effects on Enthalpies of Protonation of (L(3))M(CO)(3) Complexes (M = W, Mo).

Titration calorimetry has been used to determine the enthalpies of protonation (DeltaH(HM)) for the reaction of (L(3))M(CO)(3) complexes, where M = W and Mo and L(3) = cyclic and noncyclic tridentate ligands of the N, S, and P donor atoms, with CF(3)SO(3)H in 1,2-dichloroethane solution at 25 degrees C to give (L(3))M(CO)(3)(H)(+)CF(3)SO(3)(-). The basicities (-DeltaH(HM)) increase with the ligand donor groups (X, Y, or Z) in the order S