Structure and Photochemical Isomerization of the Dinuclear Gold(I) Halide Bis(diphenylphosphanyl)ethylene Complexes: Correlation Between Quantum Yield and Aurophilicity

Abstract

The crystal structures for cis‐(Ph2PCH=CHPPh2)(AuI)2 and trans‐(Ph2PCH=CHPPh2)(AuI)2 are reported. The structure of cis‐(Ph2PCH=CHPPh2)(AuI)2 reveals a short intramolecular Au–Au distance of 2.9526(5) Å, while the structure of trans‐(Ph2PCH=CHPPh2)(AuI)2 shows intermolecular Au–Au distances of 3.2292(7) Å. Structural data for the iodide complexes are compared to previously reported crystal structural data for cis‐ and trans‐(Ph2PCH=CHPPh2)(AuCl)2 and dppbz(AuCl)2. The quantum yields for the photochemical isomerization of cis‐(Ph2PCH=CHPPh2)(AuX)2 with 334‐nm light, Φ(cis → trans), are 0.204, 0.269, and 0.363 for X = Cl, Br, and I, respectively. Prior results from ab initio calculations on the model cis‐ and trans‐Au2X2C2H2(PH2)2 complexes aid in the interpretation of the correlation between the quantum yield for isomerization and the calculated aurophilic attraction potential V(Re). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Photochemical reactivity of two gold(I) dinuclear complexes, cis/trans-(AupNBT)2dppee: Isomerization for the cis-(AupNBT)2dppee isomer, radical substitution for trans-(AupNBT)2dppee

“…Eggleston et al [29] report an intermolecular gold-gold distance of 3.043 Å between two molecules of trans-(AuCl) 2 dppee in the crystal. In the unit cell of trans-(AuI) 2 dppee [12] there are two dimers, each with an intermolecular gold-gold distance of 3.2292 Å. A crystal structure of an analogous thiophenol, trans-(AuSPh) 2 dppee [35], shows an infinite chain forming a two-dimensional network held together by intermolecular gold-gold interactions and p-p interactions of the SPh ligands.…”

“…Quantum yields, measured at 334 nm for the halides were found to be U = 0.204 ± 0.062 (Cl), 0.269 ± 0.092 (Br), 0.363 ± 0.0 55 (I) [12]. Ab initio calculations [13] attribute the isomerization to a p ⁄ excited state accessible to the cis isomer because of the intramolecular gold-gold interaction.…”

Steric effects and aurophilic interactions in crystals of Au2(μ-1,2-bis(diphenylphosphino)ethane)X2 and Au2(μ-1,2-bis(dicyclohexylphosphino)ethane)X2 (X = Cl, Br, I)

“…32 However, Au 2 (µ-cis-dppee)I 2 , where dppee is cis-di(phenylphosphine)ethylene, has a structure of type (C) with the two gold centers positioned closer together with a Au•••Au distance of 2.9526(5) Å. 25 The differences between the structure of Au 2 (µ-dcpe)X 2 and those of Au 2 (µ-dcpe)Br 2 and Au 2 (µ-dcpe)I 2 are likely to result from subtle differences in packing efficiency that are tied to the differences in the lengths of the Au-X bonds, the sizes of the halides, and the strength of the aurophilic interactions.…”

“…Thus, Au 2 (µ-cis-dppee)X 2 (dppee is cis-bis(diphenylphosphine)ethylene) adopts structure of type (C) because the rigid backbone positions the two gold centers in close proximity. 24,25 Finally, molecules of the type Au 2 (µ-R 2 P(CH 2 ) n PR 2 )X 2 may have no aurophilic interactions at all as shown in (D) in Scheme 1. With four known structural motifs possible for the Au 2 (µ-dppe)X 2 and Au 2 (µ-dcpe)X 2 series, we identify here which motifs are actually found for these two series and explore their luminescent properties.…”

Partition of electronic excitation energies: the IQA/EOM-CCSD method

“…The study of molecules and molecular clusters in excited states has opened exciting possibilities in organic and inorganic chemistry. For example, photoexcitation might induce (i) a substantial increase in acidity [1,2] (ii) ultrafast intramolecular proton transfers [3] , (iii) isomerisations [4,5] , (iv) polymerisations using incident intensities reduced in two orders of magnitude relative to those of usual initiators [6] , and (v) changes in chemical structure which can be used in the design of molecular switches [7] among many other effects. Besides these advances, our understanding of physical and chemical processes of molecules in excited states will play a critical role in the development of emergent technologies, like the production of photovoltaic cells [8,9] , the use of artificial photosynthesis to generate biofuel [10] and biological detection and imaging [11] .…”