Aurophilicity

The non-relativistic band structures of silver and gold are very similar so that, were it not for relativistic effects, gold would look silver . 

Copyright 1990 John Wiley. Reprinted by permission of John Wiley Sons, Inc.) 

Iso-structural series of transition-metal and main-group clusters. 

The mean Au- Au distance from the central atom to the surrounding atoms is 268 pm, and the mean distance between the ten Au vertices is 298 pm. 

Structure of some gold oligomeric aggregate molecules (a) Au5(mes)5 (mes = C6H3Me3-2,4,6) (b) [LAuClb, 1--------------1 

Aurophilicity presumably arises from relativistic modification of the gold valence AOs energies, which brings the 5d and 6s orbitals into close proximity in the energy level diagram. In more recent theoretical studies, the effect is primarily attributed to electron correlation, which takes precedence over 6s/5d hybridization. To date, the origin of the aurophilicity has not yet been unambiguously established. 

Some mixed Au and Ag metal complexes (filled circle, Au open circle, Ag) (a) [Au(CH2PPh2)2]2[Ag(0C103)2]2, 

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Alkene complexes Alkynyl complexes Ammine complexes Aqueous chemistry Arsine complexes Auranofin Auride ion Aurophilicity Binary compounds Bond lengths acetylacetonate complex alkyls and aryls ammine complexes carboxylates cyanide complexes dialkyl sulphide complexes dithiocarbamates to gold... 

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. 

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... 

Hayashi, A., Olmstead, M.M., Attar, S. and Balch, A.L. (2002) Crystal chemistry of the Gold (I) trimer, Au3(NC5H4)3 formation of hourglass figures and self-assodation through aurophilic attraction. Journal of the American Chemical Society, 124, 5791-5795. 

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,... 

Another interesting example of aurophilic interactions influencing electronic excited state properties is the unusual photochemical cis to trans conversion observed in dinudear goldhalide bis(diphenylphosphino)ethylene complexes, Au2X2(dppee)... 

Schmidbaur, H. (2000) The Aurophilicity Phenomenon A Decade of Experimental Findings, Theoretical Concepts and Emerging Applications. Gold Bulletin, 33, 3-10. 

Scherbaum, F., Grohmann, A., Huber, B., Kruger, C. and Schmidbaur, H. (1988) Aurophilicity as a Consequence of Relativistic Effects The Hexakis (triphenylphosphaneaurio)methane Dication [(Ph3PAu)6C]2. Angewandte Chemie International Edition, 27, 1544-1546. 

Pyykkd, P. and Zhao, Y.-F. (1991) Ab initio calculations on the (ClAuPH )2 dimer with relativistic pseudopotential Is the aurophilic attraction a correlation effect Angewandte Chemie International Edition, 30, 604—605. 

Runeberg, N., Schiitz, M. and Werner, H.-J. (1999) The aurophilic attraction as interpreted by local correlation methods. Journal of Chemical Physics, 110, 7210-7215. 

Ray, L., Shaikh, M.M. and Ghosh, P. (2008) Shorter Argentophilic Interaction than Aurophilic Interaction in a Pair of Dimeric (NHC)MC1 2 (M=Ag, Au) Complexes Supported over a N/O-Functionalized N-Heterocyclic Carbene (NHC) Ligand. Inorganic Chemistry, 47, 230-240. 

Zhang, H.-X. and Che, C.-M. (2001) Aurophilic Attraction and Luminescence of Binuclear Gold(I) Complexes with Bridging Phosphine Ligands ah initio Study. Chemistry - A European Journal, 7, 4887-4893. 

Pan, Q.-J. and Zhang, H.-X. (2003) Aurophilic attraction and excited-state properties of binuclear Au(I) complexes with bridging phosphine and/or thiolate ligands An ah initio study. Journal of Chemical Physics, 119, 4346-4352. 

Rosch, N., Gorling, A., Ellis, D.E. and Schmidbaur, H. (1989) Aurophilicity as Concerted Effect Relativistic MO Calculations on Carbon-Centered Gold Clusters. Angewandte Chemie International Edition, 28, 1357-1359. 

Pyykkd, P. and Runeberg, N. (2002) Icosahedral WAU]2 A Predicted Closed-Shell Species, Stabilized by Aurophilic Attraction and Relativity and in Accord with the 18-Electron Rule. Angewandte... 

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