Spontaneous Resolution of a Triple‐Stranded Dinickel(II) Helicate Generated via Intermolecular Transamination Reaction of S ‐Methylisothiocarbohydrazide in the Presence of Ni 2+

The reaction of S-methylisothiocarbohydrazide hydroiodide [H2NNHC(SCH3)NNH2·HI] with NiCl2·6H2O in water at room temperature yielded a triple-stranded dinickel(II) helicate [NiII(L1–L1)3NiII]I4·4H2O (14+·4I–·4H2O), where L1–L1 = H2NNHC(SCH3)NNC(SCH3)NHNH2, in 35 % yield, which spontaneously separates in enantiomers upon crystallization. The enantiomers do not racemize at room temperature, even not after 15 h of heating at 90 °C. X-ray diffraction structures of both enantiomers, chiroptical and magnetic properties of 14+·4I–·4H2O are reported. Demetallation of the complex by treatment with S2– resulted in 3,6-bis(methylthio)-1,4-dihydro-1,2,4,5-tetrazine (2). Compound 2 undergoes 2-e– oxidat…