Latent metathesis catalyst stabilized with NO2⋯I interaction

A modified Hoveyda–Grubbs metathesis catalyst incorporating a chelating 2-iodo-3-nitrobenzylidene ligand is described. The complex displays very little activity in model metathesis reactions at rt, while easily initiates at slightly elevated temperatures. Latent behavior of the catalyst is attributed to a through-space electron-donating effect of the nitro group, which stabilizes the chelate by the formation of NO2 → I → Ru triad.