Hydrogen Exchange Reactions in C₆₀

Michael McKee, Department of Chemistry, Auburn University

The interactions of several H₂ molecules (H₂)_n n=1-5 within C₆₀, C₇₀, and C₈₂ have been studies with several density functional methods as well as with MP2 and SCS-MP2.  As expected B3LYP, significantly underestimates dispersion interactions while the M05-2X and M06-2X methods are in much better agreement with SCS-MP2 results.  Degenerate exchange reactions were calculated for 3H₂; 3H₂ inside C₆₀, C₇₀ and C₈₂.  The free energy barrier at 298 K is reduced from 88.8 to 36.2 kcal/mol within C₆₀.  Steric compression, dispersion, and a favorable entropy contribution contribute similar increments to the barrier reduction.  At 298K k_cat/k_uncat = 10³⁶.

Oral