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.