Phosphorus-31, cadmium-111, cadmium-113 and mercury-199 N.M.R. studies of cadmium(II) halide and mixed cadmium(II)-mercury(II) halide complexes with tributylphosphine

Abstract

Phosphorus-31, cadmium-111 and cadmium-113 n.m.r, studies have been carried out on CdX₂(PBu₃)₂ (where X = Cl, Br, I). The results are consistent with exchange of both phosphine and halogen. Phosphine exchange becomes slow on the N.M.R. time scale in all cases by -40°C. Mixtures of CdX₂(PBu₃)₂ with different halogens give averaged signals at room temperature, but below about -80°C exchange becomes slow and halogen redistribution reactions can be observed.    

Reaction of CdX₂ and PBu₃ in 1 : 1 proportions in ethanol gives Cd₂X₄(PBu₃)₃ as the isolated product, not Cd₂X₄(PBu₃)₂. It is shown that ethanol is an effective ligand to cadmium and redistribution reactions between coordinated ethanol and the phosphine occur.    

The mixed metal complexes CdHgX₄(PBu₃)₂ have been shown by phosphorus-31, cadmium-113 and mercury-199 n.m.r, studies to have all the phosphine coordinated to mercury.    

Cadmium-111 and cadmium-113 chemical shifts in these compounds span a range of over 500 ppm and shifts have been correlated with ³¹P chemical shifts and the coupling constant J_P,Cd.