A THEORETICAL APPROACH TO THE COMPLEXATION AND DECOMPLEXATION PROCESSES IN THE REACTION C-60+HE-REVERSIBLE-ARROW(HE-AT-C-60)

摘要

To theoretically investigate the complexation and decomplexation processes in the reaction C-60 + He reversible arrow (He @ C-60), four possible reaction paths are assumed, so that while He approaches and penetrates the C-60 cage (a) a pentagon, (b) a hexagon, (c) a short bond, or (d) a long bond will be expanded on its original sphere or plane to form a window. The computation is performed by the quantum chemical method EHMO/ASED. The results show that the probability of completing this reaction in terms of the tunnel effect can be neglected and the reaction is completed by overcoming a potential barrier of the reaction. It is easily completed by opening a planar window than by opening a spherical window. The probability through reaction path (b) with a barrier of 1247.94 kJ/mol is larger than that through reaction path (a) with a barrier of 1438.26 kJ/mol, when the planar expansion forming a window of a 9-membered ring is at the optimized value of 0.40 Angstrom. When He deviates the center and approaches the C-60 cage, there will be a charge distribution on C-60 with changing in size and even in sign along the longitude corresponding to the symmetry axis, but the absolute value gradually decreases. This situation is similar to the charge transfer on carbons in straight-chain polyene. (C) 1995 John Wiley & Sons, Inc. [References: 29]