The Energy Profile of Proton Transfer from Brønsted Acids to Terminal Hydrides in Transition Metal Complexes Can Be Estimated by Combining in situ IR and NMR Spectroscopy

The enthalpy and entropy changes relative to the stepwise reaction of [(triphos)Re(CO)2H] with perfluoro-tert-butyl alcohol in CH2Cl2 to give first the hydrogen-bonded adduct [(triphos)Re(CO)2H···HOC(CF3)3] and then the stable nonclassical dihydrogen complex [(triphos)Re(CO)2(η2-H2)]+ have been estimated by a combination of in situ IR and NMR experiments in the temperature range from 200 to 260 K [triphos = MeC(CH2PPh2)3].