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rium isotope effect); (iv) regular (type A) isotope effects usually have r us. log Tcurves confined t o the 1.33-1.55 range and exhibiting relatively little structure [occasional exceptions were manifested in small negative deviations appearing in the high-temperature region (T = 1000'K) where, if exhibited by rQM for rates, they would probably be washed out of r by n]; (v) in both anomalous and regular cases, the infinite-temperature asymptotic limit to r is 1.333, as demanded by theory4 (this limit, however, can be approached from either above or below). Representative samples of the r us. log T plots for the equilibrium isotope effect cases are shown in Figure 11. It can be concluded from the work described in this report that one may use the usual estimates of r to calculate deuterium isotope effects from measured tritium effects, or vice versa, only if one is sure that the individual isotope effects are in the normal direction (klight> kheavy),reflect significant force constant changes at the isotopic position(s) between reactant and transition state, and exhibit regular (type A'O) temperature behavior throughout the entire temperature range (0
