Synthesis and spectral studies of platinum complexes of para-substituted 4-phenylthiosemicarbazides

Article abstract of DOI:10.1016/S1386-1425(97)00054-1

Platinum(II) complexes of para-substituted 4-phenylthiosemicarbazides, RPhNHCSNHNH₂ (R = H, CH₃, Br, F and NO₂) have been prepared and characterised by infrared and multinuclear NMR spectroscopy. The thiosemicarbazides act as bidentate ligands bonding through the sulphur and hydrazinic nitrogen atoms to form mixtures of cis- and trans-isomers of square planar complexes. ¹H and ¹⁹⁵Pt NMR spectroscopy suggest that the trans-isomer predominates in solution and that the relative ratio of trans: cis increases with increasing temperature of synthesis. ¹⁵N NMR spectroscopy has also been used to assign the cis- and trans-isomers of platinum complexes of ¹⁵N enriched 4-(4′-bromophenyl)thiosemicarbazide using ¹⁵N chemical shifts and |¹J ¹⁹⁵Pt-¹⁵N| values. The magnitude of the coupling constant |¹J ¹⁹⁵Pt-¹⁵N| of 238 Hz compares favourably with other platinum(II) complexes in which the ¹⁵N donor atom is trans to ¹⁵N and thus confirms the assignment of the trans-isomer as the predominant one in solution.