Formation of bidentate metal chelates from some related pyridine compounds

2,2?-Dipyridylamine (dpa), 2-pyridyl-2-thiazolylamine (pta), 2,2?- dipyridyl sulphide (dps), 2,2?-dipyridyl sulphone (dpso), and 2,2?- dipyridylmethane (dpm) have been shown to function as bidentate chelating agents with various metal ions. A qualitative consideration of their metal complexes establishes the following stability sequence: dpa ˜ pta > dps > dpm > dpso.