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 Delta S(double dagger)contribution to Delta G(double dagger)for iEDDA addition.