Recently accumulated experimental evidence for aurophilic interactions in and between molecular gold(I) compounds and the results of pertinent theoretical calculations are reviewed for the period from 2007 to mid-2011. The influence of the intra- and intermolecular bonding contacts between the closed-shell metal centres, Au-Au, on the molecular and crystal structures, and the consequences of these effects for the chemical and physical properties of gold compounds are summarized for the various classes of mono- and polynuclear systems. The literature survey builds on the contents of previous reviews and relates new experimental and theoretical findings to earlier observations (353 references).

The decade 1990-2000 saw a growing interest in aurophilic interactions in gold chemistry. These interactions were found to influence significantly a variety of structural and other physical characteristics of gold(I) compounds. The attention paid to this unusual and counterintuitive type of intra- and intermolecular bonding between seemingly closed-shell metal centers has rapidly been extended to also include silver chemistry. Hundreds of experimental and computational studies have since been dedicated to the argentophilicity phenomenon. The results of this development are reviewed herein focusing on molecular systems where two or more silver(I) centers are in close contact leading to specific structural characteristics and a variety of novel physical properties. These include strongly modified ligand-to-metal charge-transfer processes observed in absorption and emission spectroscopy, but also colossal positive and negative thermal expansion on the one hand and unprecedented negative linear compressibility of crystal parameters on the other.

There is now compelling experimental evidence for the existence of specific intra- and intermolecular bonding between seemingly closed-shell gold(I) centers (5d10) which manifests itself in all areas of gold chemistry. This "aurophilic interaction", which had not been predicted by conventional valence theory, was found to be associated with binding energies in some cases exceeding even those of strong hydrogen bonds and therefore to be highly significant in co-determining molecular structure and dynamics. In high-level theoretical treatments the attraction is rationalized as a "super van der Waals bonding" based on particularly strong relativistic, dispersion and correlation effects (critical review, 265 references).

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The term 'aurophilicity' was introduced in 1989 to describe phenomena in the structural chemistry of gold which could not be readily rationalized by conventional concepts of chemical bonding. In the following decade the aurophilicity concept has been widely applied and supported by the results of many experimental as well as theoretical studies. It will be carried over into the new millennium as a continued incentive for investigations that will help in the understanding of the unique properties of gold.

Chemists today are increasingly fascinated by gold's unique position in the family of elements. In this review, the author looks at important new results emerging from recent research in gold chemistry.

The class of “porcupine compounds”, includes the title cation 1, whose structure has been determined as the BPh4 salt. The analytically, mass‐spectrometrically and crystallographically detected interstitial C atom occupies the crystallographic inversion center in an octahedron composed of gold atoms: the structure is probably stabilized by AuċAu interactions. The periphery of tetraauriomethanes is apparently “aurophile” with respect to further LAu⊕ ions, so that the hypervalent complex cation [C(AuL)6]2⊕ is formed spontaneously. The supposedly uncentered octahedral cluster cations formulated previously as (AuL) 62⊕ were in fact probably indentical with the C‐centered species described here.

We introduce the collection of reviews in this thematic issue of Chemical Society Reviews that demonstrate and discuss the current cutting edge research in the field of gold chemistry and materials science as it stands today. We also highlight achievements in the fields of gold catalysis, gold nanoparticles and the preparative, structural and theoretical chemistry of gold, and discuss the remaining challenges and opportunities. Our aim is to inspire further discovery in these new and deeply fascinating fields.