Phosphorus-31, mercury-199 and selenium-77 n.m.r. studies of ligand exchange reactions in mercury(II) halide complexes

Abstract

Mercury(II) halide complexes of tris(4-methoxyphenyl)phosphine have been investigated by ³¹P and ¹⁹⁹Hg n.m.r. spectroscopy of CH₂Cl₂ solutions. At room temperature the phosphine exchanges at an appreciable rate and halogen exchange is fast. At -50°C both phosphine and halogen exchange are slow on the n.m.r. time scale and halogen redistribution reactions are observed.    

Mercury(II) halide complexes with tributylphosphine selenide have been investigated by ³¹P, ¹⁹⁹Hg and ⁷⁷Se n.m.r. methods. This ligand is labile and exchanges rapidly on the n.m.r. time scale at room temperature, although the exchange can be slowed down at about -100°C. Halogen exchange is also fast at room temperature.

    Ligand exchange reactions between tributylphosphine and either tris(4-methoxyphenyl)phosphine or tributylphosphine selenide were investigated and redistribution reactions to give mixed ligand complexes were observed.