Abstract: Free energy changes of each primary steps in one-step hydride transfer and multistep transfer mechanisms in the reductions of protonated N-arylfluorenimines by an NAD (P) Hmodel, BANH, were derived from approprlate thermodynamic cycles by combining PK_a.and relevant electrochemical data, The mechanism of the reduction was proposed as onestep hydride transfer from thermodynamic points of view and the isotope-labelling experiments.

Key words: BNAH, N-Arylfluorenimines, Thermodynamic energetics, One-step hydride transter mechanism