Methanide-gold complexes

The presence of an excess of electron density on the carbon atom in methanide gold (III) complexes permits them to act as C-donor nucleophiles forming dinuclear or even polynuclear derivatives. 

SCHEME 5. Synthesis of a polynuclear gold complex containing bis(diphenylphosphino)methanide ligands... 

Very few examples of bridging non-cyclic methanides of gold are known. Among them the complex 79 has been reported as the result of the reaction of phosphine-phosphonium derivatives with acetylacetonate derivatives of gold(I) [103,104]. The complexes 80 [89,98], already seen in previous paragraphs, cor-... 

Thus, the abstraction of the chlorine atom in [Au(QF5)2Cl(dppm)j [175] provides a mononuclear gold(I II) derivative with the diphosphine acting as a chelate ligand, which is an excellent starting material in the synthesis of dinuclear or polynuclear methanide and methanidiide complexes after deprotonation of the dppm ligand (first deprotonation with HNa and the second with acetylacetonate gold(I) derivatives) [198-201] (Scheme 3.3)... 

Bardaji, M., Gimeno, M.C., Jones, P.G., Laguna, A., Laguna, M., Merchan, F. and Romeo, I. (1997) Carbon-Carbon Coupling via Nucleophilic Addition of a Gold(l) Methanide Complex to Heterocumulenes. Organometallics, 16(5), 1083-1085. 

Bidentate phosphines such as Ph2PCH2PPh2 or Ph2PNHPPh2 form cyclic dinuclear complexes with gold(I). These complexes can be deprotonated with strong bases to give the corresponding methanide or amide complex as shown in equation (7). 

An alternative strategy for the preparation of mononuclear ylide complexes is to start from gold(I) precursors which already contain an ylide ligand. Displacement in such complexes of tetrahydrothiophene, SC4H8, by neutral or anionic ligands (including polyfunctional phosphines, acetylides, carbonyl metalates and methanide complexes) leads to a variety of mono-, di- and tetranuclear compounds of remarkable stability (Scheme 9)55,114,211... 

---