Facile Synthesis of (Phosphine)- and (N-heterocyclic Carbene)Gold(I) and Silver(I) Azide Complexes

Two general protocols for the synthesis of N-heterocyclic carbene- or phosphine-ligated gold(I) and silver(I) azide complexes have been developed. The first utilizes thallium(l) acetylacetonate, followed by treatment with trimethylsilyl azide, while the second protocol exploits the relative weakness of d(10) metal-oxygen bonds in the reaction of metal(I) acetate with trimethylsilyl azide. Both methods give products in high yield, but only the metal(I) acetate/trimethylsilyl azide method proceeds to completion for an N-heterocyclic carbene-ligated silver(I) acetate. The successful application of this method to silver(I) suggests that this nonaqueous protocol may have general applicability to late transition element or main group acetate precursors. Eight new complexes are reported, of which six are metal azides; four have been crystallographically characterized. Products have been characterized by vibrational and multinuclear NMR spectroscopies and combustion analysis. The synthesis methods described here provide useful alternatives for the syntheses of azide complexes in cases where protic solvents cannot be used.