Experimental and Theoretical Evidence of the Existence of Gold(I)⋅⋅⋅Mercury(II) Interactions in Solution through Fluorescence‐Quenching Measurements

Abstract

Heteronuclear complexes {[Hg(R)2][Au(R')(PMe3)]2}n (R=R'=C6Cl2F3 (3); R=R'=C6F5 (4); R=C6Cl2F3, R'=C6F5 (5); R=C6F5, R'=C6Cl2F3 (6)) were prepared by the treatment of the corresponding organomercury compounds, [Hg(C6X5)2], with two equivalents of [Au(C6X5)(PMe3)]. Their crystal structures, as determined by using X-ray diffraction methods, display Au···Hg interactions. Although only compound 4 and 5 show luminescence in the solid state, all of these compounds quench the fluorescence of naphthalene in solution. Solution studies of these derivatives suggest a cooperative effect of the gold(I) center in switching on the quenching capabilities of the [Hg(C6X5)2] synthon with naphthalene. Theoretical studies confirmed the quenching ability of the organomercury species in the presence of gold.

Tri‐ and Tetranuclear Metal‐String Complexes with Metallophilic d10–d10 Interactions

“…In this way, the two conformers adopt Au‐Hg‐Au transoid and cisoid arrangements, respectively. Overall, the Au⋅⋅⋅Hg contacts of 6 (3.0253(4) to 3.4082(4) Å) are somewhat longer than the Au–Au contacts in 3 – 5 , but are close to intermolecular Au⋅⋅⋅Hg distances (3.097(2)–3.498(3) Å) observed recently for a number of so called molecular Au–Hg amalgams, as well as the intramolecular Au⋅⋅⋅Hg distances (3.112(1)–3.2940(9) Å) observed for some similar complexes . Complex 6 may be also regarded as a metallo‐pincer complex [ClHg( AuCAu )] between Hg II and the anionic tridentate ligand [2,6‐(Ph 2 PAuCl) 2 C 6 H 3 ] − ( AuCAu ) − containing a central carbanionic binding site and two “gold‐arms” contributing pincer‐type chelation through metallophilic interactions.…”

The Energetic Significance of Metallophilic Interactions

“…electrostatic interactions were also found to dominate the dimeric packing modes of literature examples of other Au(I) complexes 5, 6, and 7 (Figure 4). [22,[30][31] The dispersion contribution scales qualitatively with the contact area of the dimers. Interestingly, the orbital component is the most consistent across all four species, suggesting that this is a transferrable characteristic of aurophilic interactions.…”

“…Electrostatic potentials (left) and computed energy decomposition analysis (right) determined from the crystal structures of complex 2 and literature complexes 5, 6, and 7. [22,31] Electrostatic potential surfaces calculated using M06/LACVP level, and EDA calculations performed using the ADF2017.110 package at ZORA-PBE-D3BJ/TZ2P level. electrostatic interactions were also found to dominate the dimeric packing modes of literature examples of other Au(I) complexes 5, 6, and 7 (Figure 4).…”

[AuHg(o-C6H4PPh2)2I]: A Dinuclear Heterometallic Blue Emitter

“…Thus, we have described complexes with d 10 -d 10 interactions between Au I and their group congeners Ag I or Cu I [8][9][10][11][12][13]; d 10 -d 8 interactions as, for instance, those appearing in the complexes [Hg{Au(C6F5)Cl2(μ-2-C6H4PPh2)}2] or [{AuCl(Ph2PCH2SPh)}2PdCl2] [14,15]; or with post-transition metals as Tl I , Sn II or Bi III , in which the interactions are of the type d 10 -s 2 [16][17][18]. In addition, very recently, we reported the synthesis of complexes displaying unsupported Au I -Hg II interactions, that in addition to their interesting structural characteristics show fascinating luminescent properties or even the capability to quench very effectively the emission of organic molecules [19,20].…”

“…Usually, complexes displaying Au(I)-M(I) (M = coinage metals) or Au(I)-Hg(II) interactions show emission lifetimes in the nanosecond range, and colors in the yellow-orange range of the visible spectrum, which was assigned to delocalized excitons in extended chains or two-or three-dimensional networks [8][9][10][11][12][13]19,20]. Only a few cases complexes behave as blue emitters and show longer (microsecond) lifetimes.…”