The field of multimetallic catalysis is rapidly developing and some multimetallic complexes catalyze organic transformations to yield the desired products in more efficient ways owing to the combined ...action of different metals in a cooperative fashion. This Concept article describes the recent advances of cooperative catalysis playing in multimetallic systems such as homo‐multimetallic complexes with short metal‐metal distances, homo‐multimetallic complexes with long metal‐metal distances, hetero‐multimetallic complexes and metallocene‐based multimetallic complexes with special attention towards redox‐switchable catalysis. Examples are illustrated in which the use of multimetallic complexes show clear enhancement of catalytic outcomes when compared with the sum of their corresponding mononuclear counterparts. Furthermore, several examples are discussed showing the effects of electronic communication in cooperative systems.
Teamwork: In this Concept article the authors discuss selected examples of cooperativity in multimetallic systems. Homobimetallic systems with short and long metal‐metal distances are considered, and the interplay of the different metals in several heterometallic complexes is reviewed. Cooperativity in metallocene‐based systems and their utilization in redox‐switchable catalysis is also discussed.
The synthesis of heterobimetallic AuI/RuII complexes of the general formula syn‐ and anti‐{AuCl}(L1∩L2){Ru(bpy)2}PF62 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}PF62 and the bimetallic analogue syn‐{AuCl}(L1∩L2){Ru(bpy)2}PF62, 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}PF62 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.
Acting in concert: Novel heterobimetallic AuI/RuII complexes synthesized in a Diels‐Alder reaction are reported. The applied post‐functionalization strategy allows which isomer is obtained to be controlled. Their application as catalysts in carbon‐phosphorus cross‐coupling showed that the dinuclear complexes can outperform their monometallic counterparts
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).
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).
Let's play dominoes with SF6: The photoredox catalytic activation of SF6 in the presence of a‐substituted styrenes and alkynols initiates a reaction sequence that consecutively forms a C−O bond, a ...C−C bond and a C−SF5 bond, one after another. Finally, this domino reaction yields pentafluorosulfanylated oxygen‐containing heterocycles in a single step. These new compounds bear a complex structure and broaden the scope of pentafluorosulfanylated building blocks for chemical synthesis in the future. More information can be found in the Communication by D. Rombach, B. Birenheide, and H.‐A. Wagenknecht. (DOI: 10.1002/chem.202100767).
Virtually inert sulfur hexafluoride becomes a precious pentafluorosulfanylation agent, if properly activated by photoredox catalysis, to access α‐fluoro and α‐alkoxy SF5‐compounds. This advanced ...protocol converts SF6 in the presence of alkynols as bifunctional C−C‐ and C−O‐bond forming reagents directly into pentafluorosulfanylated oxygen‐containing heterocycles in a single step from α‐substituted alkenes. The proposed mechanism is supported by theoretical calculations and gives insights not only in the pentafluorosulfanylation step but also into formation of the carbon‐carbon bond and is in full agreement with Baldwin's cyclization rules. The key step is a radical type 5‐, 6‐ respectively 7‐exo‐dig‐cyclization. The synthesized oxaheterocycles cannot be simply prepared by other synthetic methods, show a high level of structural complexity and significantly expand the scope of pentafluorosulfanylated building blocks valuable for medicinal and material chemistry.
Become complex! The advanced one‐step photoredox catalytic activation of SF6 allows the preparation of pentaflurosulfanylated oxepans, tetrahydropyrans and tetrahydrofurans as products with high structural complexity.
Virtually inert sulfur hexafluoride becomes a precious pentafluorosulfanylation agent, if properly activated by photoredox catalysis, to access α-fluoro and α-alkoxy SF
-compounds. This advanced ...protocol converts SF
in the presence of alkynols as bifunctional C-C- and C-O-bond forming reagents directly into pentafluorosulfanylated oxygen-containing heterocycles in a single step from α-substituted alkenes. The proposed mechanism is supported by theoretical calculations and gives insights not only in the pentafluorosulfanylation step but also into formation of the carbon-carbon bond and is in full agreement with Baldwin's cyclization rules. The key step is a radical type 5-, 6- respectively 7-exo-dig-cyclization. The synthesized oxaheterocycles cannot be simply prepared by other synthetic methods, show a high level of structural complexity and significantly expand the scope of pentafluorosulfanylated building blocks valuable for medicinal and material chemistry.
One‐electron oxidation converts the ferrocene‐substituted borane into a Lewis superacid, as reported by Frank Breher, Jan Paradies, and co‐workers in their Communication (e202216959). The Lewis ...superacid activates almost inert carbon–fluorine and sulfur–fluorine bonds for reductions, alkylations, and arylations to form new chemical bonds.
A series of redox‐responsive ferrocenyl‐substituted boranes and boronic esters were synthesized. Oxidation of the ferrocenyl ligand to the ferrocenium resulted in a drastic increase in the Lewis ...acidity beyond the strength of SbF5, which was investigated experimentally and computationally. The resulting highly Lewis acidic boron compounds were used for catalytic C−F and S−F bond activation.
The oxidation of ferrocenyl‐substituted boranes and boronic esters allows for the straightforward synthesis of strong boron‐centered Lewis superacids. The Lewis superacids were characterized by NMR, XRD and FIA computation. The ferrocenium‐substituted boranes were applied in catalytic C−F and S−F bond activations.
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