Tetrazine derived mononuclear RuII(acac)2(L) (1), [RuII(bpy)2(L)](ClO4)2 (2) and [RuII(bpy)(L)2](ClO4)2 (3) (L = 3-amino-6-(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine, acac = acetylacetonate, bpy = 2,2′-bipyridine): syntheses, structures, spectra

Tetrazine derived rather uncommon mononuclear ruthenium complexes 1, 2 and 3 were prepared. The free tetrazine based ligand exists as a dimeric entity in the solid state via hydrogen bonding interactions with water molecules present in the lattice. 1 exhibits unusually strong bonds especially from RuII to tetrazine-N (1.913(2) Å).