NMR characterisation and dynamic behaviour of [Pt(bipy)(R-Thiourea)2]Cl2 and [Pt(phen)(R-Thiourea)2]Cl2 complexes

• We have achieved the complete and total characterisation of new PtII–thiourea complexes in solution by heteronuclear NMR.
• We confirm the chemical features by IT-TOF mass spectra.
• We compare these results with those obtained from PdII analogues.
• The overall NMR properties are discussed adding specific knowledge about these systems with potential biological activities.

We have recently reported the synthesis, characterisation and dynamic behaviour of 10 [Pd(bipy)(R-TU)2]Cl2 and [Pd(phen)(R-TU)2]Cl2 (bipy = 2,2′-bipyridyl; phen = 1,10-phenanthroline; R-TU = N-alkyl substituted thioureas) complexes; in this paper PtII analogues are presented to achieve a complete overview on this class of molecules. As expected, PtII derivatives increase the rotation barrier about the thioureas C–N bonds and once again the metal has proved to select preferential conformations for both mono and dialkyl thioureas. In this study, beyond the many shared features of the 20 PtII and PdII complexes, we extensively issue all the data concerning 13C, 15N and 195Pt hetero-nuclear NMR, stressing out the chemical shift differences that any free ligand undergoes upon coordination. To achieve this goal all the hetero-nuclear experiments were performed for the 7 free ligands and the 20 complexes in the same experimental conditions. Further support to the determined structures and dynamics is provided by mass spectrometry measurements by an ion-trap time-of-flight (IT-TOF) detector.

A thorough multinuclear NMR analysis and MS-TOF spectra shed light on a topic so far neglected: structural features and dynamic behaviour of d8 metal thiourea complexes in solution. A comparative analysis of free ligands, PtII and PdII complexes is reported along with the specific dynamic behaviour.Figure optionsDownload as PowerPoint slide