Luminescent Gold(I) and Silver(I) Complexes of 2-(Diphenylphosphino)-1-methylimidazole (dpim): Characterization of a Three-Coordinate Au(I)−Ag(I) Dimer with a Short Metal−Metal Separation
dataset
posted on 2003-12-15, 00:00 authored by Vincent J. Catalano, Stephen J. HornerThe Au(I) and Ag(I) closed-shell metal dimers of 2-(diphenylphosphino)-1-methylimidazole, dpim, were investigated.
dpim formed the discreet binuclear species [Ag<sub>2</sub>(dpim)<sub>2</sub>(CH<sub>3</sub>CN)<sub>2</sub>]<sup>2+</sup> (<b>1</b>) when reacted with appropriate Ag(I) salts.
Likewise, [Au<sub>2</sub>(dpim)<sub>2</sub>]<sup>2+</sup> (<b>3</b>) and [AuAg(dpim)<sub>3</sub>]<sup>2+</sup> (<b>4</b>) were produced via reactions with (tht)AuCl, tht is
tetrahydrothiophene, and Ag(I). Compound <b>3</b> exhibits an intense blue luminescence (λ<sub>max</sub> = 483 nm) in the solid
state. However, upon initial formation of <b>3</b>, a small impurity of Cl<sup>-</sup> was present giving rise to an orange emission
(λ<sub>max</sub> = 548 nm). Attempts to form [Au<sub>2</sub>(dpim)<sub>2</sub>]Cl<sub>2</sub> yielded only (dpim)AuCl (<b>2</b>), which is not visibly emissive. The
rare three-coordinate heterobimetallic complex [AuAg(dpim)<sub>3</sub>]<sup>2+</sup> (<b>4</b>) exhibits intense luminescence in the solid-state
resembling that of <b>3</b>. The crystal structures of <b>1</b><b>−</b><b>4</b> were determined, revealing strong intramolecular aurophilic and
argentophilic interactions in the dimeric compounds. Compound <b>1</b> has an Ag(I)−Ag(I) separation of 2.9932(9) Å,
while compound <b>3</b> has a Au(I)−Au(I) separation of 2.8174(10) Å. Compound <b>4</b> represents the first example of a
three-coordinate Au(I)−Ag(I) dimer and has a metal−metal separation of 2.8635(15) Å. The linear Au(I) monomer,
<b>2</b>, has no intermolecular Au(I)−Au(I) interactions, with the closest separation greater than 6.8 Å.
