Reaction mechanisms of dissociative chemisorption of HI, I 2 , and CH 3 I on a magic cluster Al 13 −

We have investigated the transition‐state structures and reaction mechanisms for the dissociative chemisorption reactions of HI, I 2 , and CH 3 I on the magic cluster Al   13 − . The HI, I 2 , and CH 3 I molecules approach Al   13 −with an end‐on orientation rather than a side‐on orientation because of the more effective orbital overlap in the end‐on orientation. The reactions of Al   13 −with HI and I 2 would produce Al 13 HI – and Al 13 I 2 − , respectively, because of large exothermic energy changes and relatively small activation energies. The reaction of Al   13 −with CH 3 I is unlikely to take place because of the low mobility of CH 3 on Al   13 −and the high activation barrier for the S N 2‐type reaction. The dissociative chemisorption reactions are preferred thermodynamically to the abstractive chemisorption reactions. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008