Halogen-gold derivatives

The chemistry of compounds with gold-germanium bonds has developed considerably since Schmidbaur and coworkers reported the first derivatives obtained by the insertion reaction of GeCl2 (as its dioxane complex) into a gold-halogen bond [75]. Both neutral and ionic compounds have been reported and a larger structural diversity in comparison with the silicon analogs has been established (Table 4.4). 

Complexes [AuX3(PR3)] are usually prepared by oxidation of the gold(I) derivative [AuX(PR3)j with the corresponding halogen. Mixed halogen complexes can be prepared in a similar way as in equation (70).329 7... 

The halogen acids do not form salts with the tetrammino-auric ion in solution, for if an aqueous solution of potassium chloride be added to tetrammino-auric nitrate a yellow colour is produced, and a yellow precipitate formed which apparently is a derivative of explosive gold chloride. 

Homoleptic complexes with bidentate C C donor ylide derivatives are well known. Oxidative addition of some gold(I) [Au2 (CH2)2PR2 2] species by addition of halogen, pseudo-halogen, or alkyl halide affords dinuclear Au(II) complexes which... 

This type of interatomic contact is sometimes found in halogen or chalcogen gold derivatives, and the vast majority of the examples described in the literature are of the type X- X, that is, they contain the same element in both extremes of the interaction. Of these, the most frequent are I- -I or S- -S interactions, although there are other non-metal- non-metal contacts, such as F- F, Br- -Br, Se- -Se or - - . 

Research in this area was developed further by Li et at. using 1,3-dienes 64 for the gold-catalyzed annulation of phenols and naphtols [58, 59]. These generated various dihydrobenzofuran derivatives. The best yields were achieved when the catalytic system included enough AuCl3 and silver salt to remove halogen atoms and deliver cationic gold. 

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