Synthesis,characterization, and solution behavior of mercury(II) chloride complexes with phosphine tellurides

The reaction of mercury(II) chloride with neutral phosphine telluride ligands (R₃PTe) produced new mercury(II) complexes, HgCl₂(R₃PTe)₂ R = Me₂N (1), Et₂N (2), C₄H₈N (3), C₅H₁₀N (4) or ^n-Bu (5)]. Attempts to isolate the complex of HgCl₂ with the morpholinyl ligand, (OC₄H₈N)₃PTe, were unsuccessful. Complexes 1–5 have been characterized by elemental analyses, IR, and multinuclear (³¹P, ¹²⁵Te, and ¹⁹⁹Hg) NMR spectroscopy. The solution behavior of the complexes was investigated using variable temperature NMR spectroscopy in the presence of excess ligand and indicated fast ligand exchange on the NMR timescale at room temperature. The metal–ligand exchange barriers in these complexes were estimated to be in the range 8–11 kcal/mol. The results suggest that a slight change in the nature of the substituents on the phosphorus of the ligand can contribute considerably to the lability of the complex obtained. The NMR data are discussed and compared with those obtained for related phosphine chalcogenide systems.