Kinetics of formation of dihydrogen complexes by protonation of CpRuHL complexes (L = DPPM, DPPE, 2 PPh3) with HBF4 center dot Et2O in THF and the failure to observe dihydrogen complexes in the reactions with other acids

The second-order rate constants for the reactions of the title complexes wi th HBF4 in THF do not correlate with the previously reported pK(a)'s of the se complexes. The lack of formation of dihydrogen complexes in their reacti ons with HCl, HBr, or CF3COOH in THF and acetone solutions indicates the li mited validity of predictions based on aqueous pK(a) scales.