Aurophilic bonding

The TCNQ molecule in [TR(bzim)]2-TCNQ is sandwiched between two units of [ J,-N, C -bzimAu]3 in a face-to-face manner so that it is best represented by the formula (7t-[ J,-N, C -bzimAu]3)( j,-TCNQ)(7t-[p-N, C -bzimAu]3). The cyanide groups clearly are not coordinated to the gold atoms. The distance between the centroid of TCNQ to the centroid of the AU3 unit is 3.964 A. The packing of [TR(bzim)]2-TCNQ shows a stacked linear-chain structure with a repeat pattern of-(Au3)(Au3)(p-TCNQ) (Au3)(Au3)(p-TCNQ)- an ABBABB repeat The complex [TR(bzim)]2-TCNQ contains two very short intermolecular Au Au distances of 3.152 A (identical for the two aurophilic bonds). The intermolecular Au Au distance is even shorter than the intramolecular distances in the starting compound, which are 3.475, 3.471, and 3.534 A. The adjacent AU3 units in [TR(bzim)]2-TCNQ form a chair-type structure rather than the face-to-face (nearly eclipsed) pattern reported in Balch s studies of the nitro-9-fluorenones adducts with the trinuclear Au(I) alkyl-substituted carbeniate complexes. 

Cao, L., Jennings, M.C. and Puddephatt, R.J. (2007) Amine-amide equilibrium in gold(III) complexes and a gold(III)-gold(I) aurophilic bond. Inorganic Chemistry,... 

Bachman, R.E., Fioritto, M.S., Fetics, S.K and Cocker, T.M. (2001) The Structural and Functional Equivalence of Aurophilic and Hydrogen Bonding Evidence for the First Examples of Rotator Phases Induced by Aurophilic Bonding. Journal of the American Chemical Society, 123, 5376-5377. 

A large number of these complexes has been prepared via the above direct route or via other methods (below). The structure features a linear skeleton. With small ligands L, the compounds are generally associated into oligomers or polymers via aurophilic bonding, as recently demonstrated for Me3PAuC=CPh.26... 

Unusual aurophilic bonding between gold in different oxidation states appears to be responsible for the adduct formation between (G6F5)3Au and cyclic ylide complexes with gold in the oxidation state +1 and +2 and in related compounds with an ionic structure (Scheme 24)155-157... 

Structure and bonding in cyclic ylide complexes have been studied extensively in earlier experimental and theoretical work.2 There is general agreement that transannular aurophilic bonding has a significant influence on the stability and reactivity of this family of compounds. There is also evidence for inter -molecular aurophilic bonding between these auracycles, but the number of examples is still limited (Scheme 43) 27455-i57,i8i... 

Cations Au+ have been embedded between parallel -C=C-Au-C=C- units connecting two calixarenes (Scheme 82). The symmetrical side-on coordination is slightly distorted to allow for aurophilic bonding.51... 

The electron-rich trinudear Au3 (bzim) 3 and Au3 (carb) 3 react with F6 to yield the sandwich clusters [n Au3(bzim)3 2](PF6) 29 and [n Au3(carb)3 2](PF6) 30 [54]. The cation of both compounds contains atom which interacts in a distorted trigonal prismatic coordination with six Au(I) atoms from two cyclic Au3C3N3 moieties at Au- distances ranging from 2.971(1) to 3.107(1) A, indicative of appretiable metal-metal interaction. Two Au(I) atoms on each planar trinudear unit are involved in intermolecular aurophilic bonding interactions [Au-Au 3.109(1)/3.066(1) A in 29 3.059(1)/3.052(1) A in 30], thus resulting in an infinite columnar chain with a BBABBA- pattern (Figure 4.11). 

A] to form [(Tab)2M][Au(CN)2] units. Two such fragments are further connected by one gold-gold aurophilic bonding interaction [Au-Au 3.0140(5) A] to form an uncommon Ag-Au-Au-Ag linear string structure with three ligand-unsupported metal-metal bonds [605]. 

T-coordination. In the presence of donors, L, linear 1 1 complexes are generated (equations 10 and 11). Dinuclear complexes LAuC CAuL are also readily accessible (equation 12), and are found to be associated into aggregates through aurophilic bonding (An- Au). ... 

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