Unsymmetrical Pt(II) pincer complexes of tridentate NN’S- and NN’Se-mono(iminophosphorane) ligands: Synthesis, characterization and solid state structure

Four indole-substituted tridentate iminophosphorane ligands carrying NN’S- and NN’Se-donor atoms, i.e., HL^SMe, HL^SPh, HL^SeMe and HL^SePh, were prepared and combined with [Pt(SMe₂)₂Cl₂] to yield complexes of the compositions [Pt(L^SMe)Cl] (1a), [Pt(L^SPh)Cl] (1b), [Pt(L^SeMe)Cl] (2a) and [Pt(L^SePh)Cl] (2b). Product characterization by elemental analysis, mass spectrometry, NMR spectroscopy (¹H/¹³C/³¹P) and single-crystal X-ray diffraction revealed complexes with metal ions embedded in unsymmetrical square-planar coordination environments and largely planar ligand skeletons with extensive π-delocalization. The residual Pt-Cl bond and multiple options for ligand structure modification make this Pt(II) complex class promising for the future development of catalytic and pharmaceutical applications.