Selective formation of heteroligated Pt(II) complexes with bidentate phosphine-thioether (P, S) and phosphine-selenoether (P, Se) ligands via the halide-induced ligand rearrangement reaction

Bidentate phosphine-selenoether (P, Se) ligands were synthesized, and their heteroligated Pt(II) complexes were made and studied. The unique "P, S/P, Se" ligand coordination to Pt(II) can be realized via the halide-induced ligand rearrangement reaction. In all cases, the exclusive formation of semi-open heteroligated complexes was achieved as shown by ³¹P and ⁷⁷Se NMR spectroscopy and from single crystal X-ray diffraction studies. This is the first example of the use of ⁷⁷Se NMR spectroscopy to characterize these types of structures through direct observation of the weak-link interaction with the metal center. Heteroligated structure formation is believed to be driven by the relative electrondonating ability of the substituent groups on the seleno or thioether moieties. This effect is studied by comparing the structures of corresponding P, SMe and P, SeMe complexes bearing a hemilabile P, SCH₂CF₃ group, which is less sterically demanding than P, SPh but is similar in terms of electron withdrawing ability.