Importance of frontier orbital interactions in addition reaction of water to disilene

Addition mechanisms of water to disilene were investigated in detail using the high level ah initio molecular orbital (MO) theory. We have found that the search for transition states by ab initio MO calculations combined with the frontier MO theory provides a good perspective view of the mechanisms of the reaction of disilenes and water. The initial electrophilic and nuele ophilic interactions of the water with disilene give the corresponding weak complexes, C-E and C-N, which leads to the next nucleophilic and electroph ilic attack of the water part, respectively. The latter pathway requires an antarafacial approach, while the former pathway proceeds via suprafacial a ddition. Whereas in the model disilene-water addition reaction, the pathway from C-E is more favorable than the pathway from C-N, the stereochemical a mbiguity of the addition reactions found experimentally may be explained by the competition of the two pathways. (C) 2001 John Wiley & Sons, Inc.