Reactivity of 1.1.1-Propellane with (silox)3M (M = Ti, V, Cr): Structures of (silox)3V=(cC4H4)=CH2 and [(silox)3Cr-(1.1.1-C5H6)-]2

Application of the two-orbital, two-electron, four-state paradigm to 1.1.1-propellane (111P), which contains an unusual ???inverted??? central bond, suggests that an electrophilic metal center can activate it toward ring opening. Low-valent, early-metal complexes ((silox)3M (M = Ti (1), V (2) (or M = V(THF) (2-THF), Cr (3))) were employed to test this assessment with mixed results. Facile ring opening of 111P occurs for 1, producing known degradation products, and 2, which generates the alkylidene (silox)V=(cC4H4)=CH2 (2= C5H6), a species capable of catalyzing the ROMP (ring-opening metathesis polymerization) of norbornene. For 3 and 111P, a radical-like dimerization to [(silox)3Cr-(1.1.1-C5H6)???]2 (or (silox)3Cr(C5H6)2Cr(silox)3 (32P2)) effectively competes with ring opening. In conjunction with the experiments, high-level calculations provide a rationale for the trichotomy in reactivity. Superscript/Subscript Available更多