Novel ligational behaviour of thiosalicylohydrazide and its derivatives with cobalt(II), nickel(II), copper(II), and palladium(II)

Abstract

The metal (Co^II, Co^III, Ni^II, Cu^II, and Pd^II) complexes of thiosalicylohydrazide, H₂L¹[o-HOC₆H₄C(S)N¹-R¹N²R²R³, R¹= R²= R³= H], and its derivatives H₂L²(R¹= H, R²= R³= Me), HL³(R¹= Me, R²= R³= H), H₂L⁴(R¹= R²= H, R²= Ph), and HL⁵(R¹= Ph, R²= R³= H) have been prepared and characterised. The compounds H₂L¹, H₂L², and H₂L⁴ act as monobasic bidentate ligands {except in [Pd(HL⁴)₂] where one ligand is bidentate and the other one is tridentate to form a five-co-ordinate neutral chelate} to form neutral chelates. Compounds HL³ and HL⁵ behave as both bi- and tri-dentate species and form four-co-ordinate cationic aquocobalt(II), aquo- and halogeno-copper(II), Zwitterionic palladium(II) chelates, and five-co-ordinate cationic halogenonickel(II) chelates. The chelating ligands show four types of co-ordination, i.e. N¹O, N²S, OS, and N²OS. The structural relationships of the complexes are discussed.