Gold(I) complexation with trialkyl/triaryl phosphine selenide ligands

A number of phosphine selenide ligands and their gold(I) complexes of gener al formula R3P=Se-Au-X (where X is Cl-, Br- and CN- and R=phenyl, cyclohexy l and tolyl) were prepared. The complexes were characterized by elemental a nalysis, IR and P-31 NMR spectroscopic methods. In the IR spectra of all co mplexes a decrease in frequency of P=Se bond upon coordination was observed , indicating a decrease in P=Se bond order. P-31 NMR showed that the electr onegativity of the substituents is the most important factor determining th e P-31 NMR chemical shift. It was observed that phosphorus resonance is mor e downfield in alkyl substituted phosphine selenides, as compared to the ar yl substituted ones. Ligand disproportionation in the complex Cy3P=SeAuCN i n solution to form [Au(CN)(2)](-) and [(Cy3P=Se)(2)Au](+) was investigated by C-13 and N-15 NMR spectroscopy.