Synthesis, structure and spectroscopic properties of some thiosemicarbazone complexes of platinum

Abstract

Reaction of salicyldehyde thosemicarbazone (H₂L¹), 2-hydroxyacetophenone thiosemicarbazone (H₂L²) and 2-hydroxynapthaldehyde thiosemicarbazone (H₂L³) (general abbreviation H₂L, where H₂ stands for the two dissociable protons, one phenolic proton and one hydrazinic proton) with K₂[PtCl₄] afforded a family of polymeric complexes of type [{Pt(L)}_n]. Reaction of the polymeric species with two monodentate ligands (D), viz. triphenylphosphine (PPh₃) and 4-picoline (pic), yielded complexes of the type [Pt(L)(D)]. These mixed-ligand complexes were also obtained from the reaction of the thiosemicarbazones with [Pt(PPh₃)₂Cl₂] and [Pt(pic)₂Cl₂]. The crystal structure of [Pt(PPh₃)(L²)] has been determined. The thiosemicarbazone ligands are coordinated, via dissociation of the two protons, as dianionic tridentate O,N,S-donors. The [Pt(L)(D)] complexes show characteristic ¹H NMR spectra and intense absorptions in the visible and ultraviolet region. They also fluoresce in the visible region at ambient temperature.