Au interactions

The soft Au+ forms relatively few complexes compared with those of phosphines. Complexes with ammines, nitriles and diazoles like Au(NH3)2 and Au(RCN)2 are known but little studied. In linear Au(NH3)2, Au-N is 2.01-2.03 A [70a], [Au(NCPh)2]+ has been used as a labile source of other gold complexes [70b]. AuCl(piperidine) is a monomer with weak tetra-meric association in contrast AuX(py) (X = Cl, Br, I) are [Aupy2]+[AuX2] with a chain structure in the solid state (and Au-Au interactions), suggesting a close balance between factors for molecular and ionic structures [70c] (note also the tetrahydrothiophene complexes in section 4.10.6). 

Intramolecular Au-Au interactions are found in some binuclear complexes (AuX)2, where X is a chelating ligand like dithiocarbamate, phosphine ylid (R2P(CH2)2) or bidentate phosphines. Therefore, in [Au(S2CNBu2)]2 the Au-Au distance is 2.78 A (Figure 4.50). 

A related dinuclear species 77, recently described, constitutes the first dinuclear gold(I) complex with heterobridged phosphor-1,1 -dithiolato moieties and bis(ylide) bridging ligands [ 102]. It is obtained by reaction between [ AuS2PPh2] and the diylide gold complex 74 (R=Me). No intermolecular Au-Au interaction is observed in 77 but the oxidative addition of chlorine to the product leads to a new complex 78 in which a single bond is formed between the two Au(II) centers (Scheme 26). 

The Lewis acid Hg3( i-C6F4)3 also forms a pi-acid/pi-base interaction with TR(carb). In addition to the crystal structure demonstrating the ABBABB pattern observed in other stacked materials which retain the aurophilic Au-Au interactions between four of the six basic Au(I) atoms of the BB moieties, studies have shown that the oligomeric acid/base interection is retained in solution. Pulsed gradient diffusion NMR studies [70] suggesting the oligomeric sizes and coupling... 

When [AuTl(C6F5)2]n reacts with DMSO the complex [Tl2 Au(C6F5)2 2 lt-DMSO 3]n [126] is obtained. The crystal structure of this complex shows unsupported Au - Tl interactions that range from 3.2225(6) to 3.5182(8) A but there are no Tl- - - Tl interactions. There are Au- - - Au interactions of3.733 A and the gold centers are almost linearly coordinated to two pentafluorophenyl groups. The complex is strongly luminescent both at room temperature (emits at 440 nm (exc.390 nm)) and at 77 K (emits at 460 nm (exc. 360 nm)). 

The complex obtained with ferrocenylmethylpyrazole (9) is noteworthy because the structure [151] shows the molecules associated into pairs via intermolecular Au Au interactions of 3.1204(6) A and these pairs form chains held together by H Au and H F interactions. The 3D supramolecular structure is formed through additional C— H F hydrogen bonds. These types of H F and H Au interactions are not common in pentafluorophenylgold chemistry. 

Besides intermolecular Au Au interactions, visible metal-centered emission of mononuclear Au(I) complexes is usually associated with trigonal, non-centro-symmetric coordination at Au(I). For example, mononuclear two-coordinate bis... 

Vickery, J.C., Olmstead, M.M., Fung, E.Y. and Balch, A.L. (1997) Solvent-stimulated luminescence from the supramolecular aggregation of a trinuclear gold(I) complex that displays extensive intermolecular Au Au interactions. Angewandte Chemie, 109, 1227-1229 (1997) Angewandte Chemie (International Edition in English), 36, 1179-1181. 

AuCl(alkene)] (alkene = m-cyclooctene. norbornene, CHf/o-dicyclopentadiene ) complexes have been obtained by reaction of [AuCl(CO)] with the alkene.2280,2281 The structure of [AuC1(Ci0H12)] shows the ligand //2-bonded to gold via the C=C bond in the norbornene ring and the molecules are associated into dimers through Au Au interactions.2281... 

Neutral complexes with azolate ligands of the type [AuL(PPh3)], with L representing differently substituted pyrazolates,2251,2366 imidazolates,365,2 69 2370 benzidimidazolates, 71 2372 triazolate,2373 tetraazolate (403),536 or 2,2 -bibenzimidazolates (404),2374,2375 have been prepared. The structure of the [Au(l,2,4-triaz)(PPh3)] is a dimer with Au-,Au interactions (405).23 3 The antimicrobial... 

The structure of the trimer [Au3(NC5H4)3] has been studied and shows that individual molecules self-associate through aurophilic interactions into two distinct structural motifs that involve both extended chains of molecules connected by pairwise and individual Au---Au contacts, and discrete dimers linked by pairwise Au---Au interactions (Figure 25).3131... 

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