Abstract
Dinuclear gold(I) compounds are of great interest due to their aurophilic interactions that influence their photophysical properties. Herein, we showcase that gold-gold interactions can be influenced by tuning the electronic properties of the ligands. Therefore, various para substituted (R) N,N'-bis(2,6-dimethylphenyl)formamidinate ligands (pRXylForm; Xyl = 2,6-dimethylphenyl and Form = formamidinate) were treated with Au(tht)Cl (tht = tetrahydrothiophene) to give via salt metathesis the corresponding gold(I) compounds [pRXylForm2Au2] (R = -OMe, -Me, -Ph, -H, -SMe, and -CO2Me). All complexes showed intense luminescence properties at low temperatures. Alignment with the Hammett parameter σp revealed the trends in the 1H and 13C NMR spectra. These results showed the influence of the donor-acceptor abilities of different substituents on the ligand system which were confirmed with calculated orbital energies. Photophysical investigations showed their lifetimes in the millisecond range indicating phosphorescence processes and revealed a redshift with the decreasing donor ability of the substituents in the solid state.
Highlights
Due to its applications in various fields such as catalysis, medicine and small molecule activation, increasing research on molecular gold(I) compounds has been observed during the last few decades.[1]
The differently substituted amidine ligands L1–L6 were synthesised by an ethanol condensation reaction from the corresponding amines and triethyl orthoformate (Scheme 2).[55–64]
We established a second route for obtaining this ligand by synthesising N,N′-bis(4-bromo-2,6dimethylphenyl)formamidine first,[57] followed by cross coupling under similar conditions (Scheme 3)
Summary
Due to its applications in various fields such as catalysis, medicine and small molecule activation, increasing research on molecular gold(I) compounds has been observed during the last few decades.[1]. As a scale for the intensity of the electronic influence, the Hammett parameter was applied.[52,53] Similar studies have been reported by Tunik et al, who investigated the influence of the ligand substituents of gold–copper alkynyl complexes on their photoluminescence properties. We report the synthesis of six different dinuclear gold complexes exhibiting fully supported aurophilic interactions by using a variety of formamidinate ligands with different substituents in para position on the 2,6-dimethylphenyl side groups.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
