Synthesis of New Donor-Substituted Biphenyls: Pre-ligands for Highly Luminescent (C^C^D) Gold(III) Pincer Complexes |
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Authors: | Wolfram Feuerstein Dr Christof Holzer Xin Gui Dr Lilly Neumeier Prof Dr Wim Klopper Prof Dr Frank Breher |
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Institution: | 1. Institute of Inorganic Chemistry, Karlsruhe Institute of, Technology (KIT), Engesserstr. 15, 76131 Karlsruhe, Germany;2. Institute of Theoretical Solid State Physics, Karlsruhe Institute of, Technology (KIT), Wolfgang-Gaede-Straße 1, 76131 Karlsruhe, Germany;3. Institute of Physical Chemistry, Karlsruhe Institute of, Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany |
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Abstract: | 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 KAuCl4] 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. |
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Keywords: | gold complexes luminescence photophysics pincer ligand quantum chemistry |
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