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Synthesis of New Donor‐Substituted Biphenyls: Pre‐ligands for Highly Luminescent (C^C^D) Gold(III) Pincer Complexes
Author(s) -
Feuerstein Wolfram,
Holzer Christof,
Gui Xin,
Neumeier Lilly,
Klopper Wim,
Breher Frank
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202003271
Subject(s) - pincer movement , phosphorescence , carbene , chemistry , pyridine , imidazole , photochemistry , pincer ligand , diimine , ligand (biochemistry) , luminescence , crystallography , combinatorial chemistry , medicinal chemistry , stereochemistry , materials science , catalysis , organic chemistry , physics , fluorescence , biochemistry , receptor , quantum mechanics , optoelectronics
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 K[AuCl 4 ] forming non‐palindromic [(C^C^D)Au III ] 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 sp 2 and one carbenic carbon donor. The [(C^C^D)Au III ] 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.