A retro‐style arcade machine needs an oxidant or a proton to be inserted to start playing and to switch the donating capabilities of novel phosphine ligands orthogonally and reversibly. Rh‐catalysed hydrosilylation showed that these triggers can influence either the rate of conversion and/or the product distribution. The Japanese kanji for “iron” highlights the ferrocene moiety in the ligands′ metal complexes. More information can be found in the Communication by F. Dielmann, F. Breher et al. (DOI: 10.1002/chem.202101969).
Novel multistimuli-responsive phosphine ligands comprising a redox-active [3]dioxaphosphaferrocenophane backbone and a P-bound imidazolin-2-ylidenamino entity that allows switching by protonation are reported. Investigation of the corresponding metal complexes and their redox behaviour are reported and show the sensitivity of the system towards protonation and metal coordination. The experimental findings are supported by DFT calculations. Protonation and oxidation events are applied in Rhcatalysed hydrosilylations and demonstrate a remarkable influence on reactivity and/or selectivity.
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.
The synthesis and full characterization of novel 1,1′‐difunctionalized ferrocene metalloligands is described. While one cyclopentadienyl ring has been functionalized with 2,2′‐bipyridine for secondary coordination, the second Cp ring has been decorated with different aryl moieties containing electron withdrawing groups such as 4‐(CF3)C6H4 (2A) 3,5‐(CF3)2C6H3 (2B) or 4‐(NO2)C6H4 (2C). The newly developed metalloligands were reacted with [Pd(cod)Cl2] (3A–C), CuCl2 (4A–C) and trans‐[(PPh3)2Ni(Mes)Br] (5A,B) to obtain the corresponding square‐planar and dimeric square‐pyramidal complexes. The electrochemical behaviour of the ligands and complexes was investigated with the aid of cyclic voltammetry and compared with the corresponding monofunctionalized derivatives. The influence of the implemented functional groups on the nickel complexes was then confirmed for the reductive elimination reaction of an aryl ether induced by oxidation of the corresponding methoxides (6A,B,D). The experimental findings are supported by quantum chemical calculations.
Enjoying the sun: The cover illustrates the potential of heterobimetallic AuI/RuII complexes to facilitate the P arylation of H‐phosphonates with diazonium salts, while visible light kicks off the dual gold and photoredox catalytic cycle. The underlying structure of the catalysts’ coordinating ligand system is accessible by a novel postfunctionalization approach, and the stereochemistry can be controlled by the order of metal coordination and click reaction. More information can be found in the Research Article by F. Breher and co‐workers (DOI: 10.1002/chem.202201856).
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