Scheme 3. Proposed mechanism for the reaction of 9 with ethylene. (a) Calculated relative energies (kcal mol–1) for model compounds bearing 2,6-[CH(SiMe3)2]2-C6H3 (Bbp) groups instead of Bbt groups. (b) ΔE ‡ (9′–13′) = 5.9 kcal mol–1. (c) ΔE ‡ (13′–10′) = 3.4 kcal mol–1. (d) ΔE ‡ (10′–14′) = 8.6 kcal mol–1. (e) ΔE ‡ (14′–12′) = 16.4 kcal mol–1. (f) 14 and 15 are rotational isomers with respect to a rotation around the central GeH2C–CH2Ge bond. (g) ΔE ‡ (14′–15′) = 0.8 kcal mol–1. (h) ΔE ‡ (15′–11′) = 0.9 kcal mol–1.
