2‐Amino‐5‐(2‐pyridyl)‐thiadiazole as Bidentate Ligand

Abstract

AbstractThe amino substituted bidentate chelating ligand 2‐amino‐5‐(2‐pyridyl)‐1,3,4‐thiadiazole (H2L) was used to prepare 3:1‐type coordination compounds of iron(II), cobalt(II) and nickel(II). In the iron(II) perchlorate complex [FeII(H2L)3](ClO4)2·0.6MeOH·0.9H2O a 1:1 mixture of mer and fac isomers is present whereas [FeII(H2L)3](BF4)2·MeOH·H2O, [CoII(H2L)3](ClO4)2·2H2O and [NiII(H2L)3](ClO4)2·MeOH·H2O feature merely mer derivatives. Moessbauer spectroscopy and variable temperature magnetic measurements revealed the [FeII(H2L)3]2+ complex core to exist in the low‐spin state, whereas the [CoII(H2L)3]2+ complex core resides in its high‐spin state, even at very low temperatures.