Cyclic trinuclear gold complexes

The use of other potential bidentate ligands also permits the synthesis of cyclic trinuclear gold complexes that form, by stacking, supramolecular assemblies. This is the case for the trinuclear complex [Au3(NC5H4)3] [47] that crystallizes in two... 

Cyclic trinuclear gold(I) complexes provide a novel and productive strategy for achieving supramolecular structures. While molecules of this type have been known for more than twenty years, some of their remarkable properties have only been recognized recently. Some can form liquid crystals at room temperature [41], while others lead to luminescent materials with surprising properties. We will now summarize some selected examples to illustrate the behavior of these trinuclear systems. 

The first cyclic trinuclear compound of gold(I) was reported by Vaughan in 1970 [44], The complex [p,-N, C -pyAu]3 was obtained in a very good yield by adding triphenylarsine gold(I) chloride to a THF solution of 2-pyridyllithium at —40°C, Figure 1.32. 

Based on the fact that pi-acids interact with the trinuclear gold] I) pi-bases, TR(carb) and TR(bzim), the trinuclear 3,5-diphenylpyrazolate silver(I) complex was reacted with each. Mixing [Au3(carb)3] or [Au3(bzim)3] with [Ag3(p,-3,5-Ph2pz)3] in CH2CI2 in stoichiometric ratios of 1 2 and 2 1 produced the mixed metal/mixed ligand complexes in the same gold-silver ratios. The crystalline products were not the expected acid-base adducts. It is suspected that the lability of the M-N bond (M=Au, Ag) in these complexes results in the subsequent cleavage of the cyclic complexes to produce the products statistically expected from the stoichiometry of materials used [74]. As a result of the lability of Au-N and Ag-N bonds, and the stability of... 

Aurophilic attractions are also involved in the remarkable behavior of the trinuclear complex, Au3(MeN=COMe)3. The colorless cyclic complex, whose structure is shown in Figure 3.9, crystallizes in three polymorphic forms, one of which contains prismatic stacks of the gold trimers [35]. When irradiated with UV light these crystals prodnce a long-lived yellow anission. If solvent is dropped on these photoexcited crystals, bright bnrsts of light are anitted [36,37]. This process... 

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