Argentophilic Interactions

Abstract

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.

Exploring Coordination Modes: Late Transition Metal Complexes with a Methylene‐bridged Macrocyclic Tetra‐NHC Ligand

“…[15] The average length of the AgÀC carbene bonds is 2.095 , which is within the range of comparable NHC silver(I) complexes. [9b, c, 16] Hence, the structure can be understood as the result of ad elicate equilibrium between out-of-plane twisting of the macrocyclic ligand, metallophilic interactions and the quasi-linear coordination of the silver ions.…”

N‐Heterocyclic carbenes derived from imidazo‐[1,5‐a]pyridines related to natural products: synthesis, structure and potential biological activity of some corresponding gold(I) and silver(I) complexes

“…The C-Ag (2.057(2) Å) and Ag-O (2.099(2) Å) bond distances again correspond well to the average values for 48 C(carbene)-Ag-O residues found in a CCDC search (2.067 and 2.130 Å). [35] The dimers are further linked by a 'weak' but short contact H9ÁÁÁO2 (2.27 Å) to form corrugated layers parallel to (10). The C(carbene)-Ag bond length in compound 19 is comparable to that found in related NHC-silver(I) acetate complexes, and for instance, a caffeine-based NHC-silver acetate complex exhibits an Ag-C bond length of 2.067(3) Å.…”

“…Adjacent linear (176.31(7)°) C-Ag-O units are connected via an argentophilic AgÁÁÁAg contact [35] (3.2692(3) Å) to form an inversion-symmetric dimer. The C-Ag (2.057(2) Å) and Ag-O (2.099(2) Å) bond distances again correspond well to the average values for 48 C(carbene)-Ag-O residues found in a CCDC search (2.067 and 2.130 Å).…”

Silver(I) Complexes of 12‐Phenylalkynyl‐ and 12‐Triisopropylalkynylcarba‐closo‐dodecaborate Anions

“…The Ag···Ag′ distance of 3.0071(4) Å is well reproduced by a DFT calculation at the M06/def2-TZVPP/def2-ecp level of theory (2.962 Å); it is shorter than twice the van der Waal's radius (3.44 Å), [14] and it is in the range typical for argentophilic interactions. [15] The experimental (< 3σ) and calculated C≡C and B-C bonds are slightly longer than in anion 1 in its [MMIm] + salt ( Figure 1 and Table 1). According to calculations, d(C-C phenyl ) is longer in the complex, as well, but the difference is too small to be displayed by the experimental data.…”