Heterobimetallic Gold/Ruthenium Complexes Synthesized via Post-functionalization and Applied in Dual Photoredox Gold Catalysis |
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| Authors: | Lea Bayer Dr Bernhard S Birenheide Dr Felix Krämer Dr Sergei Lebedkin Prof Dr Frank Breher |
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| Institution: | 1. Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry, Division Molecular Chemistry, Engesserstraße 15, 76131 Karlsruhe, Germany;2. Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology, Postfach 3630, 76021 Karlsruhe, Germany |
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| Abstract: | The synthesis of heterobimetallic AuI/RuII complexes of the general formula syn- and anti-{AuCl}( L1 ∩ L2 ){Ru(bpy)2}]PF6]2 is reported. The ditopic bridging ligand L1 ∩ L2 refers to a P,N hybrid ligand composed of phosphine and bipyridine substructures, which was obtained via a post-functionalization strategy based on Diels-Alder reaction between a phosphole and a maleimide moiety. It was found that the stereochemistry at the phosphorus atom of the resulting 7-phosphanorbornene backbone can be controlled by executing the metal coordination and the cycloaddition reaction in a different order. All precursors, as well as the mono- and multimetallic complexes, were isolated and fully characterized by various spectroscopic methods such as NMR, IR, and UV-vis spectroscopy as well as cyclic voltammetry. Photophysical measurements show efficient phosphorescence for the investigated monometallic complex anti-( L1 ∩ L2 ){Ru(bpy)2}]PF6]2 and the bimetallic analogue syn-{AuCl}( L1 ∩ L2 ){Ru(bpy)2}]PF6]2, thus indicating a small influence of the {AuCl} fragment on the photoluminescence properties. The heterobimetallic AuI/RuII complexes syn- and anti-{AuCl}( L1 ∩ L2 ){Ru(bpy)2}]PF6]2 are both active catalysts in the P-arylation of aryldiazonium salts promoted by visible light with H-phosphonate affording arylphosphonates in yields of up to 91 %. Both dinuclear complexes outperform their monometallic counterparts. |
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| Keywords: | bimetallic complexes cooperative effects metalloligands photoredox catalysts post-functionalization |
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