Metal complexes with thiazyl chloride: single or double bond?

Many metal complexes are known with thiazyl chloride as a ligand. In some complexes, the structure of the metal–ligand bond can be described as M=N=S–Cl, whereas in other cases the structure is described as M–N≡S–Cl. The metal–nitrogen bond length goes from 1.76 to 2.28 Å. In this study, density functional theory was used to search for the reasons for these differences, taking into account both mononuclear and binuclear complexes.