Mononuclear gold units

The following section shows specific examples of association of dicoordinated mononuclear gold units which have been classified according to the nuclearity of the aggregate. Despite this general classification, the different polymorphic forms of a specific compound are discussed together, as well as the structures of complexes with small ligand variations. 

Formation of dimers is widely observed in the crystal structures of dicoordinated gold (I) mononuclear species. The majority of them are built from [AuXL] units, where X is an anionic ligand and L a neutral one. One type of such species is the well known [ AuX (PR3)] (where PR3 is a tertiary phosphine and X a halogen atom). These species can be mainly synthesized (i) from tetrachloroauric acid (Equation 2.1), or by displacement of a weakly coordinating ligand (Y), such as alkylsulfides or CO, from [AuClY]. 

Thus, in the next examples, we comment on supramolecular entities, including linear chains, two-dimensional sheets, and even three-dimensional networks. From them, perhaps the most common structural arrangement is that in which the metals form extended linear systems, usually built from mononuclear units, dinuclear, using polydentate donor ligands and polymetallic units. It is worth mentioning that in this part and also in the following we consider only structures built by gold-heterometal interactions, not bonds thus formal clusters will not be considered. 

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