Influence of Crown Thioether Ligands in the Structures and of Perhalophenyl Groups in the Optical Properties of Complexes with Argentoaurophilic Interactions

Reaction of [{Au­(C6X5)2}­Ag]n (X = Cl, F)
with the crown thioethers 1,4,7-trithiacyclononane ([9]­aneS3), 1,4,8,11-tetrathiacyclotetradecane ([14]­aneS4), or
1,4,7,10,13,16,19,22-octathiacyclotetracosane ([24]­aneS8) affords a series of heteronuclear AuI/AgI compounds of stoichiometry [{Au­(C6X5)2}­Ag­(L)x] (L = [9]­aneS3, x = 2 (1, 4); L = [14]­aneS4, x = 1 (2, 5);
L = [24]­aneS8, x = 0.5 (3, 6)) formed via Ag–S bonds and Au···Ag
contacts. X-ray diffraction studies of some of these complexes reveal
different structural arrangements and nuclearity depending on the
nature of the crown thioether ligand and on the presence or absence
of aurophilic interactions. All the complexes are luminescent in the
solid state but not in solution. Density functional theory calculations
on representative model systems of complexes 2–4 and 6 were carried out to determine the origin
of the electronic transitions responsible for their optical properties,
which strongly depend on the nature of the perhalophenyl groups bonded
to gold.