Latent metathesis catalyst stabilized with NO2⋯I interaction

• Ruthenium complex with chelating 2-iodo-3-nitrobenzylidene ligand was synthesized.
• The complex displays latent behavior as metathesis catalyst at room temperature.
• The catalytic activity strongly increases at higher temperature.
• Nitro group in ortho position to the coordinating iodine atom stabilizes the chelate.

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.

Ruthenium complex incorporating a chelating 2-iodobenzylidene ligand is stabilized by the presence of adjacent nitro group. The interaction decreases its activity as metathesis catalyst in model RCM reactions.Figure optionsDownload as PowerPoint slide