Theoretical Studies on Structures and Spectroscopic Properties of Cyclometalated Gold(III) Complexes

Synthesis of New Donor-Substituted Biphenyls: Pre-ligands for Highly Luminescent (C^C^D) Gold(III) Pincer Complexes

We herein report on new synthetic strategies for the preparation of pyridine and imidazole substituted 2,2'-dihalo biphenyls. These structures are pre-ligands suitable for the preparation of respective stannoles. The latter can successfully be transmetalated to K[AuCl4 ] forming non-palindromic [(C^C^D)AuIII ] pincer complexes featuring a lateral pyridine (D=N) or N-heterocyclic carbene (NHC, D=C') donor. The latter is the first report on a pincer complex with two formally anionic sp2 and one carbenic carbon donor. The [(C^C^D)AuIII ] complexes show intense phosphorescence in solution at room temperature. We discuss the developed multistep strategy and touch upon synthetic challenges. The prepared complexes have been fully characterized including X-ray diffraction analysis. The gold(III) complexes' photophysical properties have been investigated by absorption and emission spectroscopy as well as quantum chemical calculations on the quasi-relativistic two-component TD-DFT and GW/Bethe-Salpeter level including spin-orbit coupling. Thus, we shed light on the electronic influence of the non-palindromic pincer ligand and reveal non-radiative relaxation pathways of the different ligands employed.

Synthetic access to a phosphorescent non-palindromic pincer complex of palladium by a double oxidative addition – comproportionation sequence

A highly phosphorescent non-palindromic (C^C^N) palladium complex may be prepared by means of a double oxidative addition – comproportionation sequence, which is a new approach for the synthesis of non-palindromic pincer complexes.

Luminescent aryl–group eleven metal complexes

This perspective highlights the recent developments in the study of the photoluminescent properties of aryl–group eleven complexes. Related properties and applications such as electroluminescence, triboluminescence, mechanochromism, luminescent liquid crystals, low molecular weight gelators and photocatalysts are also discussed.

Luminescent (N^C^C) Gold(III) Complexes: Stabilized Gold(III) Fluorides

We report the design, synthesis, and application of a (N^C^C)-ligand framework able to stabilize highly electron-deprived gold(III) species. This novel platform enabled the preparation of C(sp(2))-gold(III) fluorides for the first time in monomeric, easy-to-handle, bench-stable form by a Cl/F ligand-exchange reaction. Devoid of oxidative conditions or stoichiometric use of toxic Hg salts, this method was applied to the preparation of multiple [C(sp(2))-Au(III)-F] complexes, which were used as mechanistic probes for the study of the unique properties and intrinsic reactivity of Au-F bonds. The improved photophysical properties of [(N^C^C)Au(III)] complexes compared to classical pincer (C^N^C)-Au systems paves the way for the design of new late-transition-metal-based OLEDs.

Ab initio and DFT study of luminescent cyclometalated N-heterocyclic carbene organogold(III) complexes

The structures of versatile N-heterocyclic carbene-containing Au(III) complexes in the ground and low-lying excited states have been optimized at the B3LYP functional and the single-excitation configuration interaction (CIS) method, respectively. The spectral properties are predicted with time-dependent density functional theory (TDDFT). In addition, the charge transport quality has been estimated approximately by the predicted reorganization energy (λ). As revealed from the calculations, the introduction of methyl has a bigger influence on the spectral properties than phenyl. Furthermore, we find that changing the auxiliary ligand could tune the charge transfer properties.