Metal-metal bond formation by Oxidative

Addition in Au/N Chemistry

Au(I)...Au(I) 2.71Å

Br₂

Au(II)…Au(II) 2.52 Å

Amidinates react with THTAu(I)Cl, THT = tetrahydrothiophene, to form either dinuclear or tetranuclear Au(I) products. The dinuclear species such as the one pictured here further react with halogens and alkylhalides to oxidatively add these molecules. The Au-Au bond in these Au(II) products is very short, even shorter than has been found previously with the organometallic ylide complexes previously studied by our group. The shortest gold-gold interaction observed to date is 2.47C. (Synthesis and X-ray structures of silver and gold guanidinate-like complexes. A Au(II) complex with a 2.47 A Au-Au distance. Michael D. Irwin, Hanan E. Abdou, Ahmed A. Mohamed and John P. Fackler, Jr., Chem. Commun., 2003, 2882-2883.) The oxidative addition chemistry of the amidinates being explored looks much like the chemistry of the dinuclear ylide complexes, which has been reviewed in Comprehensive Organometallic Chemistry.

With the amidinates which form tetranuclear species, the Au(I)...Au(I) distances are about 3.0 C, with the gold atoms in almost a perfect square. These products displays an interesting visible luminescence under UV light. (Gold(I) Formamidinate Clusters: The Structure, Luminescence, and Electrochemistry of the Tetranuclear, Base-Free [Au₄(ArNC(H)NAr₄]. Ahmed A. Mohamed, Hanan E. Abdou, Michael D. Irwin, Jose M. Lopez-de-Luzuriaga and John P. Fackler, Jr., J. of Cluster Sci., 2003, 14, 253-66.)