New sulfur-oxygen mixed-donor ligand N,N'-dimethyl-piperazine-3-oxo-2- thione (Me₂pipto) and its Ni(ii) and Fe(ii) complexes

Structural and electronic features of the novel title sulfur-oxygen donor ligand Me₂pipto (1), are discussed in comparison with those of the corresponding dithione ligand Me₂pipdt. A tuning of the electronic and coordination properties of the ligand, relatable to the soft/hard power of the donor atoms, is achieved. Coordination properties have been checked towards Ni(ii) and Fe(iii) cations obtaining [Ni(Me₂pipto) ₃](BF₄)₂ (2) and [Fe(Me₂pipto) ₃](BF₄)₂ (4) complexes, which show significant differences when compared with the corresponding reaction products when using Me₂pipdt.