Figure 2.

¹H NMR spectra (recorded at 300 K, 200 MHz in C₆D₆) of the reaction monitoring for the synthesis of zirconacyclopentadiene 11 a (Negishi's reagent) with naphthalene as standard (1 equiv). a) Starting material Cp₂ZrCl₂, b) naphthalene, c) starting material 10 a at t=0 min. Reaction monitoring after d) t=10 min, e) t=30 min, f) t=1 h, g) t=3 h, and h) t=22 h. i) Zirconacyclopentadiene 11 a previously isolated.23