Ylide-gold complexes synthesis

Schmidbaur. H. Hartmann, C. Reber. G. Muller, G. Isovalent and mixed-valent ylide complexes of gold The synthesis of trinuclear compounds having double paddle-wheel structure. Angew. Chem.. Int. Ed. Engl. 1987. 26. 1146. 

The compound 70 has also been reported showing the ambident character (both C- and N-coordination) of the cyano-stabilized ylide as ligand. The authors have also transposed their work concerning the keto-bis-ylide and palladium, with the synthesis of the C-bonded complex 71 or the new cycloplatinated or-thometallated compound 72. The latter by various treatments allows one to obtain other ylidic cationic complexes of platinum such as 73. A C,C,C-terdentate coordination of the keto bis-ylide, already observed with the palladium is also obtained from the reaction of 73 with gold derivatives. 

Uson, R., Laguna, A., Laguna, M. and Uson, A. (1983) A new route for the synthesis of gold(I) and gold(III) pentafluorophenyl(ylide) complexes. Inorganica Chimica Acta, 73(1),... 

Scheme 1.3 Synthesis of polynuclear gold(II) ylide complexes.

There now exists a large number of methods for the synthesis of organogold complexes with various ylide ligands. In an extensive reaction chemistry, successive oxidation of the gold centres [Au(I) -> Au(II) Au(III)] can often be accomplished. Ylide complexes of gold have therefore been summarized in the following sections regardless of their oxidation state. 

SCHEME 8. Synthesis of gold(I) complexes containing carbonyl-stabilized phosphorus ylides... 

Metallocarbene precursors other than diazocarbonyls have been examined sporadically for the generation of oxonium ylides, though not in the context of complex target synthesis. Among these, iodonium ylides and oxidative activation of allqnies in the presence of gold catalysts have shown significant promise. 

As a versatile alternative to the generation of free carbenes, Hashmi and co-workers developed a methodology for the synthesis of abnormal NHCs where the carbene is constructed directly at the metal center. Thus, a [3 + 2] dipolar cycloaddition of azomethine ylides and gold isonitriles afforded the abnormal saturated imidazolinylidene gold eomplexes 9 [eqn (3.3)]. This methodology circumvents the regioseleetivity issue of C4 vs. C5 eoordination because the carbenic carbon is pre-coordinated to the metal center in the isonitrile precursor. Moreover, this procedure provided aeeess to a new subclass of abnormal carbenes and yielded the first abnormal earbene complexes featuring a saturated heteroeyele, unlike all previous abnormal imidazolylidene complexes, derived from unsaturated heteroeyeles. 

Interest in the synthesis and reactivity of the six-membered, potentially aromatic, phosphinine ring system has also continued, but at a much lower level than in recent years. New synthetic work includes the application of the pyrylium salt route to phosphinine synthesis, this time starting from pyrylium salts bearing chiral substituents to give the related chiral phosphinines," and the development of new routes to the 2-phosphanaphthalene (137)" ° and the phosphinine-2-aldehyde (138). Also reported is an approach to the synthesis of l,2-dihydro-l,4,2-benzo-diazaphosphinines," cationic gold(I) complexes of 2,4,6-tri-t-butyl-l,3,5-triphosphabenzene," and the synthesis of some X -phosphinines from phosphonium-iodonium ylides." " ... 

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