An investigation of mechanistic aspects of the ethylene reaction by using C2D4 shows a significant amount of hydrogen4euterium scrambling, eliminating 11% D2, 74% HD, and 15% H2, which is somewhat different from the statistical distribution of 28.6% D2, 57.1% HD, and 14.3% H2. A similar experiment with [C12TiCH3]+ and C2D4 was performed by Uppal et al., I9 and, in contrast to our result, at least 85% HD is lost. Reaction of [Cp2ZrD]+ with ...