Tetrazine metallation boosts rate and regioselectivity of inverse electron demand Diels-Alder (iEDDA) addition of dienophiles.

Reported herein is the coordination of rhenium complexes to tetrazine ligand in [ReCl(CO)3(TzPy)] [1] (TzPy = 3-(2-pyridyl)-1,2,4,5-tetrazine) and the rates of addition of different dienophiles to the tetrazine. Tetrazine coordiation lowers the ΔS‡ contribution to ΔG‡ for iEDDA addition.