We recently reported a study of the steric effect on the 1 isotope dependence of 2 degrees KIEs for several hydride-transfer reactions in solution (J Am. Chem. Soc. 2015, 137, 6653). The unusual 2 KIEs decrease as the 1 isotope changes from H to D, and more in the sterically hindered systems. These were explained in terms of a more crowded tunneling ready state (TRS) conformation in D-tunneling, which has a shorter donor acceptor distance (DAD) than in H-tunneling. To examine the isotopic DAD difference explanation, in this paper, following an activated motion assisted H-tunneling model that requires a shorter DAD in a heavier isotope transfer process, we computed the 2 KIEs at various H/D positions at different DADs (2.9 angstrom to 3.5 angstrom) for the hydride-transfer reactions from 2-propanol to the xanthylium and thioxanthylium ions (Xn and TXn(+)) and their 9 -phenyl substituted derivatives (Ph(T)Xn+). The calculated 2 KIEs match the experiments and the calculated DAD effect on the 2 KIEs fits the observed 1 isotope effect on the 2 KIEs. These support the motion-assisted H-tunneling model and the isotopically different TRS conformations. Furthermore, it was found that the TRS of the sterically hindered Ph(T)Xn(+) system does not possess a longer DAD than that of the (T)Xn(+) system. This predicts a no larger 1 KIE in the former system than in the latter. The observed 1 KIE order is, however, contrary to the prediction. This implicates the stronger DAD-compression vibrations coupled to the bulky Ph(T)Xn(+) reaction coordinate.