The First Crystal Structure of a Metal-Stabilized Tetrazine Anion Radical:  Formation of a Dicopper Complex through Self-Assembly in a Comproportionation Reaction

The reaction of Cu, Cu(BF4)2, PPh3, and 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) in the appropriate amounts gave the stable radical complex [(Ph3P)2Cu(η4,μ-bptz)Cu(PPh3)2](BF4), whose crystal structure demonstrates π(Ph)/π(bptz•-)/π(Ph) interactions and the localization of the unpaired electron in the central tetrazine ring.