Consequences of orbital symmetry: Why Hoffmann was "always" right

PRES 15

Peter T. Wolczanski, ptw2@cornell.edu, Department of Chemistry & Chemical Biology, Cornell University, Baker Laboratory, Ithaca, NY 14853
Studies of oxygen atom transfer to (silox)3M (M = V, NbL (L = PMe3, 4-picoline), Ta; silox = tBuSiO) and investigations of dissociative olefin substitution in (silox)3M(olefin) (M = Nb, Ta) are readily rationalized by the principles of orbital symmetry. These orbital symmetry arguments are generalized to explain the nominally faster reactivity of the 2nd row elements as compared to those of the 3rd row. There are also related structural consequences, and features of (silox)3MX/R (M = Mo, W; X/R = Cl, Me or Et) provide an intriguing comparison.