Transition metal complexes of 2-formylpyridinethiosemicarbazone (HFpyTSC) and X-ray crystal structures of [Pd(FpyTSC)(PPh3)]PF6 and [Pd(FpyTSC)(SCN)]

The syntheses of five new complexes of the 2-formylpyridinethiosemicarbazone ligand (HFpyTSC) with Pd(II) and Rh(III) ions are described, viz., [Pd(FpyTSC)(PPh3)]PF6, [Pd(FpyTSC)(SCN)], [Pd(FpyTSC)Br], [Pd(HFpyTSC)2]Br2 and [Rh(FpyTSC)(PPh3)2Cl]ClO4. The formulation of the complexes is discussed in terms of their elemental analyses and IR, Raman, NMR (1H, 13C and 31P), mass and electronic spectra. The X-ray crystal structures of [Pd(FpyTSC)(PPh3)]PF6 and [Pd(FpyTSC)(SCN)] show that the HFpyTSC ligand coordinates to the central Pd(II) ion in a planar conformation through the pyridyl nitrogen, the azomethine nitrogen and the deprotonated thiol sulphur atom. Thus, HFpyTSC is a versatile ligand that usually acts as a mononegative tridentate ligand bonding through Npy, NCN and C–S− while, in the case of [Pd(HFpyTSC)2]Br2, it behaves as a neutral bidentate ligand via NCN and CS.