Intermolecular Interactions in Polymorphs of Trinuclear Gold(I) Complexes:  Insight into the Solvoluminescence of Au^I₃(MeNCOMe)₃

Abstract

The trinuclear complex, Au(I)3(MeN=COMe)3, which displays a number of remarkable properties including solvoluminescence, has been found to crystallize as three polymorphs. The new triclinic and monoclinic polymorphs crystallized as colorless blocks, whereas the original hexagonal polymorph formed colorless needles. These polymorphs differ in the manner in which the nearly planar molecules pack and in the nature of the aurophilic interactions between them. Each of the three polymorphs of Au(I)3(MeN=COMe)3 shows a distinctive emission spectrum, but only the original hexagonal polymorph shows the low-energy emission that is responsible for its solvoluminescence. Colorless Au(I)3(n-PentN=COMe)3 crystallized from diethyl ether as needles of an orthorhombic polymorph and blocks of a triclinic polymorph. These polymorphs differ in the orientation of the n-Pent substituents, in the orientation of the trimers with respect to one another, and in the nature of the aurophilic interactions between the molecules. Only the triclinic polymorph of Au(I)3(n-PentN=COMe)3 shows luminescence at room temperature, but it is not solvoluminescent. Colorless Au(I)3(i-PrN=COMe)3 has also been prepared and crystallographically characterized. The isopropyl groups protrude out of the plane of the nine-membered ring and prevent self-association. The closest Au...Au contact between molecules is 6.417 A. Crystalline Au(I)3(i-PrN=COMe)3 is not luminescent at room temperature.

Remarkable Luminescence Behaviors and Structural Variations of Two-Coordinate Gold(I) Complexes

“…Like a number of other Au(I) complexes, Au I 3 (MeN = COMe) 3 exists as different polymorphs. To date three polymorphs have been identified [41]. The hexagonal polymorph forms colorless needles with an intense yellow emission, while the triclinic and monoclinic polymorphs crystallize as colorless blocks.…”

“…15 Comparisons of the emission and excitation spectra of the polymorphs of Au I 3 (MeN = COMe) 3 at 298 K: A hexagonal polymorph; B triclinic polymorph; and C monoclinic polymorph. From [41] Aspects of the structures of these three polymorphs are shown in the following figures. Figure 16 shows the molecular structure of the trimer in the hexagonal polymorph and the flip disorder that results from the two positions for the methoxy methyl groups with 0.5 fractional occupancy for each group in the two alternate locations.…”

“…3 (n-PentN=COMe) 3 Two different polymorphs appeared in the product, the cyclic trimer Au I 3 (nPentN=COMe) 3 (whose structure is shown below in Scheme 1), that was ob- tained from the reaction of a methanol solution of potassium hydroxide with (Ph 3 As)Au I Cl and n-pentyl isocyanide [41]. Since these two types of crystals were obtained by evaporating a diethyl ether solution of the material, they are concomitant polymorphs.…”

Cupriphication of gold to sensitize d 10 –d 10 metal–metal bonds and near-unity phosphorescence quantum yields

“…Although the former compound was studied for decades (22,23), the crystal structure of [Au(μ-C 2 ,N 3 -BzIm)] 3 was only recently published; it exhibited a semiprismatic conformation with one long (3.558 Å) and two short (3.346 Å) intertrimer distances to manifest its strong aurophilic interactions (11). The copper precursor for 1-4 has been studied by Dias et al (24) 3 ] that nonetheless represented weaker aurophilic interaction vs. its hexagonal polymorph (27). Even with partial oxidation via organic electron acceptors, some of the aforementioned cyclotrimers exhibited shortened Au⋯Au intertrimer distances that nevertheless remained >3.15 Å (22, 23), which are still much longer than the two 2.8750(8) Å "intertrimer" Cu I -Au I bonds in 4a herein.…”

Dynamische Kristalle: visuell wahrnehmbare mechanochemische Lumineszenzänderungen von Gold‐ und anderen Übergangsmetallkomplexen

“…Es gibt bereits zahlreiche Beispiele für durch variierende aurophile Wechselwirkungen hervorgerufene Lumineszenzänderungen. [4,5] Einzelne Polymorphe von zweifach koordinierten Gold(I)-Komplexen (zum Beispiel [Au(CNC 6 H 11 ) 2 ](PF 6 ), [6] solvolumineszierendes [Au 3 (MeOC=NMe) 3 ] [7,8] und Zn[{Au(CN) 2 } 2 ] [9] ) zeigen charakteristische Emissionseigenschaften, die durch die Selbstassoziation der Gold-Ionen zustande kommen, und weisen Au···Au-Abstände im Bereich von 2.9 bis 3.5 auf.…”