Stabilizing an exotic dianionic tetrazine bridge in a Ln metallocene.

The unique electronic nature of the 1,2,4,5-tetrazine or -tetrazine (tz) ring has sparked tremendous scientific interest over the last few years. Tetrazines have found numerous applications, and their ability to coordinate to metal ions has opened the possibility of exploring their chemistry in both molecular systems and extended networks. The rich redox chemistry of -tetrazines allows them to exchange electrons and switch between their dihydro (Htz), neutral (tz), and radical (tz˙) forms.