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A series of a novel CAAC ligands featuring a spiro‐fluorene group have been synthesized and complexed with ruthenium alkylidenes, yielding the corresponding Hoveyda‐type derivatives as a new family of olefin metathesis catalysts. The novel complexes have been characterized by XRD, HRMS and NMR measurements. The synthetised complexes were tested in catalysis and showed good activity in olefin metathesis, as demonstrated on diethyl diallylmalonate and allyl acetate substrates. The unique backbone in the ligand with the large, yet inflexible condensed system renders interesting properties to the catalyst, exemplified by the good catalytic performance and improved Z‐selectivity. In addition, the complex can also serve as a hydrogenation catalyst in a consecutive (one‐pot) reaction. The latter reaction can convert allyl acetate to butane‐1,4‐diol, a valuable chemical intermediate for biodegradable polybutylene succinate (PBS). [ABSTRACT FROM AUTHOR]

Diarylacetylenes ArC≡CAr featuring condensed aromatic hydrocarbon fragments (Ar) such as naphthalene, anthracene, phenanthrene and pyrene were converted into vinylidene ligands by 1,2‐migration reactions within the coordination sphere of half‐sandwich complexes [MII(dppe)Cp]+ (MII = RuII, FeII). Comparison of the extent of conversion of the alkyne substrates to the vinylidene complexes [Ru{=C=CAr2}(dppe)Cp]+ with those obtained from acetylenes functionalized by smaller groups (H, CH3, Ph) show that the molecular volume (VM) of the migrating group and relief of steric congestion plays a role during the rearrangement process. Conversely, the H‐atoms from the larger condensed ring aryl groups that are in close proximity to the migrating sites also have a significant influence on the efficacy and extent of the reaction by restricting access of the alkyne to the metal center, resulting in a less effective migration reaction. This combination of competing steric factors (acceleration due to relief of steric congestion and restricted access of the alkyne moiety to the reaction site) is exemplified by the facile migration of 1‐pyryl entities and the low yields of vinylidene products formed from 1,2‐bis(9‐anthryl)acetylene. [ABSTRACT FROM AUTHOR]

The appropriate arrangement of near‐infrared (NIR) chromophores allows for the modification of the peak wavelength in the NIR region and efficient use of NIR light. However, the preparation of novel NIR chromophores using simple procedures remains a formidable challenge. Herein, we report the synthesis of ball‐shaped ruthenium complex oligomers. The metal complexes can be synthesized in a single step and interact strongly with NIR light. Alkyne‐substituted low‐symmetry ball‐shaped ruthenium complexes were synthesized and subjected to Eglinton coupling to obtain dehydro[12] and [18]annulene‐fused dimers and trimers. Fine‐tuning of the reaction conditions led to the selective synthesis of the target oligomers. NMR spectroscopy confirmed that the 18π‐aromatic and 12π‐antiaromatic properties of the annulene influenced the ruthenium complex chromophore, and magnetic circular dichroism spectroscopy showed changes in the electronic structure of their excited state owing to molecular‐symmetry differences. The absorption coefficient in the NIR region of the absorption spectra of the oligomers increased significantly, supporting the efficient use of light by oligomerization. The formation of oligomers using ball‐shaped metal complexes is a simple and effective strategy for controlling NIR optical properties. [ABSTRACT FROM AUTHOR]

Colloidal Ru nanoparticles (NP) display interesting catalytic properties for the hydrogenation of (hetero)arenes as they proceed efficiently in mild reaction conditions. In this work, a series of Ru based materials was used in order to selectively hydrogenate quinaldine and assess the impact of the stabilizing agent on their catalytic performances. Ru nanoparticles stabilized with polyvinylpyrrolidone (PVP) and 1‐adamantanecarboxylic acid (AdCOOH) allowed to obtain 5,6,7,8‐tetrahydroquinaldine with a remarkable selectivity in mild reaction conditions by choosing the suitable solvent. The presence of a carboxylate ligand on the surface of the Ru NP led to an increase in the activity when compared to Ru/PVP catalyst. The stabilizing agent had also an impact on the selectivity, as carboxylate ligand modified catalysts promoted the selectivity towards 1,2,3,4‐tetrahydroquinaldine, with bulky carboxylate displaying the highest ones. [ABSTRACT FROM AUTHOR]

The catalytic asymmetric synthesis of highly functionalized cyclopropanes from 2‐substituted allylic derivatives is reported. Using ethyl diazo acetate, the reaction, catalyzed by a chiral ruthenium complex (Ru(II)‐Pheox), furnished the corresponding easily separable cis and trans cyclopropanes in moderate to high yields (32‐97 %) and excellent ee (86‐99 %). This approach significantly extends the portfolio of accessible enantioenriched cyclopropanes from an underexplored class of olefins. DFT calculations suggest that an outer‐sphere mechanism is operative in this system. [ABSTRACT FROM AUTHOR]

Formamides are important feedstocks for the manufacture of many fine chemicals. State‐of‐the‐art synthesis of formamides relies on the use of an excess amount of reagents, giving copious waste and thus poor atom‐economy. Here, we report the first example of direct synthesis of N‐formamides by coupling two challenging reactions, namely reductive amination of carbonyl compounds, particularly biomass‐derived aldehydes and ketones, and fixation of CO2 in the presence of H2 over a metal‐organic framework supported ruthenium catalyst, Ru/MFM‐300(Cr). Highly selective production of N‐formamides has been observed for a wide range of carbonyl compounds. Synchrotron X‐ray powder diffraction reveals the presence of strong host‐guest binding interactions via hydrogen bonding and parallel‐displaced π⋅⋅⋅π interactions between the catalyst and adsorbed substrates facilitating the activation of substrates and promoting selectivity to formamides. The use of multifunctional porous catalysts to integrate CO2 utilisation in the synthesis of formamide products will have a significant impact in the sustainable synthesis of feedstock chemicals. [ABSTRACT FROM AUTHOR]

The selective semihydrogenation of C2H2 to C2H4 in crude C2H4 (with ~1 vol % C2H2 contamination) is a crucial process in the manufacture of polyethylene. Comparing to conventional thermalcatalytic route with Pd as catalyst under high temperature with H2 as hydrogen source, photocatalytic C2H2 reduction reaction with H2O as hydrogen source can achieve high selectivity under milder conditions, but has rarely been reported. Here, we present a kind of ultrathin metal–organic framework nanosheets (Cu‐Co‐MNSs) that demonstrate excellent catalytic activities in the semihydrogenation of C2H2. Employing Ru(bpy)32+ as the photosensitizer, this catalyst attains a noteworthy turnover number (TON) of 2124 for C2H4, coupled with an impressive selectivity of 99.5 % after 12 h visible light irradiation. This performance is comparable to molecular catalysts and notably surpasses the efficiency of bulk metal–organic framework materials. Furthermore, Cu‐Co‐MNSs achieve a 99.95 % conversion of C2H2 under industrial relevant conditions (1.10 % C2H2 in C2H4) with 90.3 % selectivity for C2H4 over C2H6, demonstrating a great potential for polymer‐grade C2H4 production. [ABSTRACT FROM AUTHOR]

Nature uses reactive components embedded in biological membranes to perform light‐driven photosynthesis. Here, a model artificial photosynthetic system for light‐driven hydrogen (H2) evolution is reported. The system is based on liposomes where amphiphilic ruthenium trisbipyridine based photosensitizer (RuC9) and the H2 evolution reaction (HER) catalyst [Mo3S13]2− are embedded in biomimetic phospholipid membranes. When DMPC was used as the main lipid of these light‐active liposomes, increased catalytic activity (TONCAT ~200) was observed compared to purely aqueous conditions. Although all tested lipid matrixes, including DMPC, DOPG, DPPC and DOPG liposomes provided similar liposomal structures according to TEM analysis, only DMPC yielded high H2 amounts. In situ scanning electrochemical microscopy (SECM) measurements using Pd microsensors revealed an induction period of around 26 minutes prior to H2 evolution, indicating an activation mechanism which might be induced by the fluid‐gel phase transition of DMPC at room temperature. Stern‐Volmer‐type quenching studies revealed that electron transfer dynamics from the excited state photosensitizer are most efficient in the DMPC lipid environment giving insight for design of artificial photosynthetic systems using lipid bilayer membranes. [ABSTRACT FROM AUTHOR]

An efficient, simple and general protocol for the selective hydration of terminal alkynes into the corresponding methyl ketones has been developed by using a cheap, easy‐to‐synthesise and sustainable FeIII‐based eutectic mixture [FeCl3 ⋅ 6H2O/Gly (3 : 1)] as both promoter and solvent for the hydration reaction, working: i) under mild (45 °C) and bench‐type reaction conditions (air); and ii) in the absence of ligands, co‐catalysts, co‐solvents or toxic, non‐abundant and expensive noble transition metals (Au, Ru, Pd). When the final methyl ketones are solid/insoluble in the eutectic mixture, the hydration reaction takes place in 30 min, and the obtained methyl ketones can be isolated by simply decanting the liquid FeIII‐DES, allowing the direct isolation of the desired ketones without VOC solvents. By using this straightforward and simple isolation protocol, we have been able to recycle the FeIII‐based eutectic mixture system up to eight consecutive times. Furthermore, the FeIII‐eutectic mixture is able to promote the selective and efficient formal oxidation of internal alkynes into 1,2‐diketones, with the possibility of recycling this system up to three consecutive times. Preliminary investigations into a possible mechanism for the oxidation of the internal alkynes seem to indicate that it proceeds through the formation of the corresponding methyl ketones and α‐chloroketones. [ABSTRACT FROM AUTHOR]

Aryl and alkenyl halides are widely used as key intermediates in organic synthesis, particularly for the formation of organometallic reagents or as radical precursors. They are also found in pharmaceutical and agrochemical ingredients. In this work, the synthesis of aryl and alkenyl halides from the corresponding fluorosulfonates using commercially available ruthenium catalysts is reported. Notably, this is the first conversion of phenols to aryl halides that is efficient with chloride, bromide, and iodide. Fluorosulfonates are readily prepared using sulfuryl fluoride (SO2F2) and less expensive substitutes for triflates. Although aryl fluorosulfonates and their reactions are well known, this is the first report of an efficient coupling of alkenyl fluorosulfonates. To finish, it was demonstrated, by means of representative examples, that the reaction is possible in a one‐pot process, starting directly from phenol or aldehyde. [ABSTRACT FROM AUTHOR]

The usage of hierarchical MFI zeolite enables a boost of the catalytic performance of Mo‐based catalysts for the olefin‐metathesis reaction. The harvest of active catalysts roots in a segmental evolution track between hierarchical zeolite and Al2O3 slices for the fabrication of active sites. The working evolution track requires the indispensable engagements from intracrystalline mesoporous surface, Al2O3 slices, and zeolitic Brønsted acid sites. The infilling of disaggregated Al2O3 slices into the intracrystalline mesopores triggers the creation of localized intrazeolite−Al2O3 interfaces, which enables the subsequent migration and trapping of surface molybdates into the micropores. The insulation of intrazeolite−Al2O3 interface or shielding of zeolitic Brønsted acid sites leads to the break of the evolution track. Our findings disclose the hidden functionality of mesoporosity as intrazeolite interface boundary for the fabrication of active sites and supply a new strategy for the rational design of zeolite catalysts. [ABSTRACT FROM AUTHOR]

The utilization of CO2 as a non‐toxic and cheap feedstock for C1 is a desirable route to achieve high value‐added chemicals. In this context, we report a highly efficient ruthenium‐catalyzed semi‐hydrogenation reaction of CO2‐derived ureas. Various alkyl and aryl urea derivatives were successfully hydrogenated to obtain the corresponding recyclable amines and formamides (up to 97 % yield), highlighting the good substrate applicability of this method, which makes this method a sustainable alternative for the hydrogenation of CO2 to formamides in the presence of amines. In the meantime, we have discovered a new pathway that enables rapid hydrogenation of urea derivatives even at lower H2 pressure (<5 bar). This methodology might provide a new insight into the reduction functionalization of CO2 under mild pressure to form new C−N bond. Based on the control experiments and the observed intermediate products, we clarify the mechanism for selective semi‐hydrogenation of ureas. [ABSTRACT FROM AUTHOR]

A set of 16 chiral ruthenium complexes containing atropisomerically stable N‐Heterocyclic Carbene (NHC) ligands was synthesized from prochiral NHC precursors. After a rapid screening in asymmetric ring‐opening‐cross metathesis (AROCM), the most effective chiral atropBIAN‐NHC Ru‐catalyst (up to 97 : 3 er) was then converted to a Z‐selective catechodithiolate complex. The latter proved to be highly efficient in Z‐selective AROCM of exo‐norbornenes affording valuable trans‐cyclopentanes with excellent Z‐selectivity (>98 %) and high enantioselectivity (up to 96.5 : 3.5 er). [ABSTRACT FROM AUTHOR]

Due to rising resistance, new antibacterial strategies are needed, including methods for targeted antibiotic release. As targeting vectors, chelating molecules called siderophores that are released by bacteria to acquire iron have been investigated for conjugation to antibacterials, leading to the clinically approved drug cefiderocol. The use of small‐molecule catalysts for prodrug activation within cells has shown promise in recent years, and here we investigate siderophore‐linked ruthenium catalysts for the activation of antibacterial prodrugs within cells. Moxifloxacin‐based prodrugs were synthesised, and their catalyst‐mediated activation was demonstrated under anaerobic, biologically relevant conditions. In the absence of catalyst, decreased antibacterial activities were observed compared to moxifloxacin versus Escherichia coli K12 (BW25113). A series of siderophore‐linked ruthenium catalysts were investigated for prodrug activation, all of which displayed a combinative antibacterial effect with the prodrug, whereas a representative example displayed little toxicity against mammalian cell lines. By employing complementary bacterial growth assays, conjugates containing siderophore units based on catechol and azotochelin were found to be most promising for intracellular prodrug activation. [ABSTRACT FROM AUTHOR]

The p‐Cymene ruthenium(II) complex is one of the most widely used catalysts in C−H activation. However, enantioselective C−H activation promoted by arene ruthenium(II) complexes has not been realized until recently. The revealed strategies include intramolecular nitrene C−H insertion, the use of chiral transient directing groups, chiral carboxylic acid, relay catalysis, and chiral arene ligands. In this minireview, these advances are summarized and discussed in the hope of spurring further developments. [ABSTRACT FROM AUTHOR]

The neutral complex dichloro‐{diethyl[(5‐phenyl‐1,3,4‐oxadiazol‐2‐ylamino)‐(4‐trifluoro‐methylphenyl)methyl]phosphonate} (p‐cymene)‐ruthenium(II) was encapsulated inside a self‐assembled hexameric host obtained upon reaction of 2,8,14,20‐tetra‐undecyl‐resorcin[4]arene and water. The formation of an inclusion complex was inferred from a combination of spectral measurements (MS, UV/Vis spectroscopy, 1H and DOSY NMR). The 31P and 19F NMR spectra are consistent with motions of the ruthenium complex inside the self‐assembled capsule. Molecular dynamics simulations carried out on the inclusion complex confirmed these intra‐cavity movements and highlighted possible supramolecular interactions between the ruthenium first coordination sphere ligands and the inner part (aromatic rings) of the capsule. The embedded ruthenium complex was assessed in the catalytic oxidation (using NaIO4 as oxidant) of mixtures of three arylmethyl alcohols into the corresponding aldehydes. The reaction kinetics were shown to vary as a function of the substrates' size, with the oxidation rate varying in the order benzylalcohol >4‐phenyl‐benzylalcohol >9‐anthracenemethanol. Control experiments realized in the absence of hexameric capsule did not allow any discrimination between the substrates. [ABSTRACT FROM AUTHOR]

Rhodium‐catalyzed acrylate synthesis from CO2 and ethylene was accomplished by using a guanidine‐based NCN pincer ligand. The repulsion between pπ‐electron of guanidine sidearms and occupied dπ orbital of rhodium center raised the level of d‐electrons close to those of formerly known d8‐ruthenium catalyst, thereby promoting the metallalactone formation from carbon dioxide and ethylene. This work fills the absence of group‐9 metal based catalyst for the acrylate synthesis and provides a designing approach for pincer‐ligated d8‐metal catalysts to utilize pπ‐dπ interaction for promoting desirable redox processes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The article discusses the development of new ruthenium catalysts that can convert post-consumer HDPE waste into butane-1,4-diol, a precursor for biodegradable and chemically recyclable materials. The process involves isomerization metathesis (ISOMET) to produce propylene, which is then used to synthesize allyl acetate. The catalysts enable consecutive olefin metathesis and hydrogenation reactions to convert allyl acetate into butane-1,4-diol. This research offers a potential solution to the problem of plastic waste by providing a method for producing sustainable materials from persistent plastics. [Extracted from the article]

Photo‐release of triphenylphosphine from a sulfonamide azobenzene ruthenium–arene complex was exploited to activate PdIICl2 into Pd0 catalyst, for the photo‐initiation of Sonogashira cross‐coupling. The transformation was initiated on demand – by using simple white LED strip lights – with a high temporal response and the ability to control reaction rate by changing the irradiation time. Various substrates were successfully applied to this photo‐initiated cross‐coupling, thus illustrating the wide functional‐group tolerance of our photo‐caged catalyst activator, without any need for sophisticated photochemistry apparatus. [ABSTRACT FROM AUTHOR]

Low‐valent metals traditionally dominate the domain of catalytic hydrogenation. However, metal‐ligand cooperating (MLC) catalytic systems, operating through heterolytic H−H bond splitting by a Lewis acidic metal and a basic ligand site, do not require an electron‐rich metal. On the contrary, high‐valent metals that induce weaker back donation facilitate heterolytic bond activation. Here we report, for the first time, the efficient hydrogenation of carbonyl and carboxyl compounds under molecular hydrogen catalyzed by a structurally well‐defined RuIV catalyst bearing a bifunctional PCP pincer ligand. The catalyst exhibits reactivity toward molecular hydrogen superior to that of the low‐valent analog and allows hydrogen activation even at room temperature. [ABSTRACT FROM AUTHOR]

To optimize light‐driven catalytic processes, light‐mediated multi‐electron transfer dynamics in molecular dyads need to be studied and correlated with structural changes focusing on the catalytically active metastable intermediates. Here, spectro‐electrochemistry has been employed to investigate the structure‐dependent photoelectron transfer kinetics in catalytically active intermediates of two Ru−Rh catalysts for light‐driven NAD+ reduction. The excited‐state reactivity of short‐lived intermediates was studied along different photoreaction pathways by resonance Raman and time‐resolved transient absorption spectro‐electrochemistry with sub‐picosecond time resolution under operando conditions. The results demonstrate, for the first time, how the bridging ligand serves as a (multi‐)electron storage structure, mediates the strength of the electronic coupling of catalytic and photocenter and impacts the targeted electron transfer as well as parasitic electron‐transfer kinetics. [ABSTRACT FROM AUTHOR]

A dicationic triruthenium complex containing a μ3‐η3‐C3 ring, [(Cp*Ru)3(μ3‐η3‐C3MeH2−)(μ3‐CH)(μ‐H)]2+ (1 a, Cp*=η5‐C5Me5), reacted with ammonia to yield a μ‐amido complex, [(Cp*Ru)3(μ3‐η3‐CHCMeCH) (μ3‐CH)(μ‐NH2)]2+ (5), via N−H bond scission. Subsequent treatment with base resulted in C−N bond formation to yield a μ3‐η2:η2‐1‐azabutadien‐4‐yl complex, [(Cp*Ru)3(μ3‐CH)(μ3‐η2:η2‐NH=CH−CMe=CH−)]+ (6 a). The azaruthenacyclopentadiene skeleton was alternatively synthesized by the photolysis of mono‐cationic complex [(Cp*Ru)3(μ3‐η3‐C3RH2−)(μ3‐CH)]+ (2 a; R=Me, 2 b; R=H) in the presence of ammonia. The C3 ring skeleton was broken via the electron transfer to the π*(C−C) orbital in the C3 ring, and a transiently generated unsaturated μ3‐allylic species can take up ammonia, resulting in N−H bond scission followed by C−N bond formation. [ABSTRACT FROM AUTHOR]

In fabricating an artificial photosynthesis (AP) electrode for water oxidation, we have devised a semiconductor‐mediator‐catalyst structure that mimics photosystem II (PSII). It is based on a surface layer of vertically grown nanorods of Fe2O3 on fluorine doped tin oxide (FTO) electrodes with a carbazole mediator base and a Ru(II) carbene complex on a nanolayer of TiO2 as a water oxidation co‐catalyst. The resulting hybrid assembly, FTO|Fe2O3|−carbazole|TiO2|−Ru(carbene), demonstrates an enhanced photoelectrochemical (PEC) water oxidation performance compared to an electrode without the added carbaozle base with an increase in photocurrent density of 2.2‐fold at 0.95 V vs. NHE and a negatively shifted onset potential of 500 mV. The enhanced PEC performance is attributable to carbazole mediator accelerated interfacial hole transfer from Fe2O3 to the Ru(II) carbene co‐catalyst, with an improved effective surface area for the water oxidation reaction and reduced charge transfer resistance. [ABSTRACT FROM AUTHOR]

Predictive catalysis must be the tool that does not replace experiments, but acts as a selective agent, so that synthetic strategies of maximum profitability are used in the laboratory in a surgical way. Here, nanotechnology has been used in olefin metathesis from homogeneous Ru‐NHC catalysts, specifically annulating a C60 fullerene to the NHC ligand. Based on results with the C60 in the backbone, a sterile change with respect to the catalysis of the metal center, an attempt has been made to bring C60 closer to the metal, by attaching it to one of the two C−N bonds of the imidazole group of the SIMes (1,3‐bis(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene) ligand (reference NHC ligand of the 2nd generation Grubbs catalysts) to increase the steric pressure of C60 in the first sphere of reactivity of the metal. The DFT calculated thermodynamics and the kinetics of SIMes‐derived systems show that they are efficient catalysts for olefin metathesis. [ABSTRACT FROM AUTHOR]

The use of iminophosphoryl‐tethered ruthenium carbene complexes to activate secondary phosphine P−H bonds is reported. Complexes of type [(p‐cymene)‐RuC(SO2Ph)(PPh2NR)] (with R = SiMe3 or 4‐C6H4−NO2) were found to exhibit different reactivities depending on the electronics of the applied phosphine and the substituent at the iminophosphoryl moiety. Hence, the electron‐rich silyl‐substituted complex undergoes cyclometallation or shift of the imine moiety after cooperative activation of the P−H bond across the M=C linkage, depending on the electronics of the applied phosphine. Deuteration experiments and computational studies proved that cyclometallation is initiated by the activation process at the M=C bond and triggered by the high electron density at the metal in the phosphido intermediates. Consistently, replacement of the trimethylsilyl (TMS) group by the electron‐withdrawing 4‐nitrophenyl substituent allowed the selective cooperative P−H activation to form stable activation products. [ABSTRACT FROM AUTHOR]

Covalent functionalisation with alkyl tails is a common method for supporting molecular catalysts and photosensitisers onto lipid bilayers, but the influence of the alkyl chain length on the photocatalytic performances of the resulting liposomes is not well understood. In this work, we first prepared a series of rhenium‐based CO2‐reduction catalysts [Re(4,4'‐(CnH2n+1)2‐bpy)(CO)3Cl] (ReCn; 4,4'‐(CnH2n+1)2‐bpy=4,4'‐dialkyl‐2,2'‐bipyridine) and ruthenium‐based photosensitisers [Ru(bpy)2(4,4'‐(CnH2n+1)2‐bpy)](PF6)2 (RuCn) with different alkyl chain lengths (n=0, 9, 12, 15, 17, and 19). We then prepared a series of PEGylated DPPC liposomes containing RuCn and ReCn, hereafter noted Cn, to perform photocatalytic CO2 reduction in the presence of sodium ascorbate. The photocatalytic performance of the Cn liposomes was found to depend on the alkyl tail length, as the turnover number for CO (TON) was inversely correlated to the alkyl chain length, with a more than fivefold higher CO production (TON=14.5) for the C9 liposomes, compared to C19 (TON=2.8). Based on immobilisation efficiency quantification, diffusion kinetics, and time‐resolved spectroscopy, we identified the main reason for this trend: two types of membrane‐bound RuCn species can be found in the membrane, either deeply buried in the bilayer and diffusing slowly, or less buried with much faster diffusion kinetics. Our data suggest that the higher photocatalytic performance of the C9 system is due to the higher fraction of the more mobile and less buried molecular species, which leads to enhanced electron transfer kinetics between RuC9 and ReC9. [ABSTRACT FROM AUTHOR]

The luminophore Ru(bpy)2(dcbpy)2+ (bpy=2,2'‐bipyridine; dcbpy=4,4'‐dicarboxy‐2,2'‐bipyridine) is covalently linked to a chitosan polymer; crosslinking by tripolyphosphate produced Ru‐decorated chitosan fibers (NS‐RuCh), with a 20 : 1 ratio between chitosan repeating units and RuII chromophores. The properties of the RuII compound are unperturbed by the chitosan structure, with NS‐RuCh exhibiting the typical metal‐to‐ligand charge‐transfer (MLCT) absorption and emission bands of RuII complexes. When crosslinks are made in the presence of IrO2 nanoparticles, such species are encapsulated within the nanofibers, thus generating the IrO2⊂NS‐RuCh system, in which both RuII photosensitizers and IrO2 water oxidation catalysts are within the nanofiber structures. NS‐RuCh and IrO2⊂NS‐RuCh have been characterized by dynamic light scattering, scanning electronic microscopy, and energy‐dispersive X‐ray analysis, which indicated a 2 : 1 ratio between RuII chromophores and IrO2 species. Photochemical water oxidation has been investigated by using IrO2⊂NS‐RuCh as the chromophore/catalyst assembly and persulfate anions as the sacrificial species: photochemical water oxidation yields O2 with a quantum yield (Φ) of 0.21, definitely higher than the Φ obtained with a similar solution containing separated Ru(bpy)32+ and IrO2 nanoparticles (0.05) or with respect to that obtained when using NS‐RuCh and "free" IrO2 nanoparticles (0.10). A fast hole‐scavenging process (rate constant, 7×104 s−1) involving the oxidized photosensitizer and the IrO2 catalyst within the IrO2⊂NS‐RuCh system is behind the improved photochemical quantum yield of IrO2⊂NS‐RuCh. [ABSTRACT FROM AUTHOR]

Alkynyl‐B(aam) (aam=anthranilamidato) derivatives are readily available bench‐stable compounds that undergo remarkably selective reactions with Bu3SnH in the presence of [Cp*RuCl]4 as the catalyst. The addition follows a stereochemically unorthodox trans‐selective course; in terms of regioselectivity, the Bu3Sn‐ unit is delivered with high fidelity to the C‐atom of the triple bond adjacent to the boracyclic head group ("alpha,trans‐addition"). This outcome is deemed to reflect a hydrogen bonding interaction between the protic −NH groups of the benzo‐1,3,2‐diazaborininone ring system and the polarized [Ru−Cl] bond in the loaded catalyst, which locks the substrate in place in a favorable orientation relative to the incoming reagent. The resulting isomerically (almost) pure gem‐dimetalated building blocks are amenable to numerous downstream functionalizations; most remarkable is the ability to subject the −B(aam) moiety to Suzuki‐Miyaura cross coupling without need for prior hydrolysis while keeping the adjacent Bu3Sn‐ group intact. Alternatively, the tin residue can be engaged in selective tin/halogen exchange without touching the boron substituent; the fact that the two ‐NH entities of −B(aam) do not protonate organozinc reagents and hence do not interfere with Negishi reactions of the alkenyl halides thus formed is another virtue of this so far underutilized boracycle. Overall, the ruthenium catalyzed trans‐hydrostannation of alkynyl‐B(aam) derivatives opens a practical gateway to isomerically pure trisubstituted alkenes of many different substitution patterns by sequential functionalization of the 1‐alkenyl‐1,1‐heterobimetallic adducts primarily formed. [ABSTRACT FROM AUTHOR]

Two di‐ and tetranuclear Ru(bda) (bda: 2,2′‐bipyridine‐6,6′‐dicarboxylate) macrocyclic complexes were synthesized and their catalytic activities in chemical and photochemical water oxidation investigated in a comparative manner to our previously reported trinuclear congener. Our studies have shown that the catalytic activities of this homologous series of multinuclear Ru(bda) macrocycles in homogeneous water oxidation are dependent on their size, exhibiting highest efficiencies for the largest tetranuclear catalyst. The turnover frequencies (TOFs) have increased from di‐ to tetranuclear macrocycles not only per catalyst molecule but more importantly also per Ru unit with TOF of 6 s−1 to 8.7 s−1 and 10.5 s−1 in chemical and 0.6 s−1 to 3.3 s−1 and 5.8 s−1 in photochemical water oxidation per Ru unit, respectively. Thus, for the first time, a clear structure–activity relationship could be established for this novel class of macrocyclic water oxidation catalysts. [ABSTRACT FROM AUTHOR]

In the past few decades, chemistry of cyclometalated species has gained momentum with increased applications in several areas of scientific developments. Cyclometalation reactions result in the formation of stable metallacycles through the generation of metal‐carbon covalent bonds by activating the unreactive Csp2‐H or Csp3‐H bonds. The extra stability gained by the formation of metallacycles enhances their applicability scopes especially in the area of homogeneous catalysis. In the recent research development in this area, NHC ligands (strong σ‐donor and generally, weak π‐acceptor) have been found to be one of the most suitable candidates for the intramolecular C−H activation process which leads to the cyclometalated species. The growth in the area of cyclometalation chemistry that started in the late 20th century is still continuing and in the past few decades, various examples of NHC derived transition metal‐based cyclometalated complexes came into the picture. As covering all the reported literatures in this area (includes mainly late transition metals) will exceed the limits of minireview, we restricted ourselves to the recent (2015 – May 2021) examples of the most common Ru‐, Rh‐, and Ir‐based CNHC^C cyclometalated complexes and their applications in various homogeneous catalytic conversions such as transfer hydrogenation, amidation, oxidation of alcohols, annulations, and so forth. [ABSTRACT FROM AUTHOR]

The ruthenium‐catalyzed synthesis of diarylmethane compounds was realized under exceedingly mild photoredox conditions without the use of exogenous photocatalysts. The versatility and robustness of the ruthenium‐catalyzed C−H benzylation was reflected by an ample scope, including multifold C−H functionalizations, as well as transformable pyrazoles, imidates and sensitive nucleosides. Mechanistic studies were indicative of a photoactive cyclometalated ruthenium complex, which also enabled versatile C−H allylations. [ABSTRACT FROM AUTHOR]

Herein we report on the development and application of chemoenzymatic Dynamic Kinetic Asymmetric Transformation (DYKAT) of α‐substituted β‐hydroxyketones (β‐HKs), using Candida antartica lipase B (CALB) as transesterification catalyst and a ruthenium complex as epimerization catalyst. An operationally simple protocol allows for an efficient preparation of highly enantiomerically enriched α‐substituted β‐oxoacetates. The products were obtained in yields up to 95 % with good diastereomeric ratios. [ABSTRACT FROM AUTHOR]

Various triaminocyclopentadienyl ruthenium complexes have been synthesized from Ru3(CO)12. The new complexes were tested for their ability to catalyze cascade conversions of propargyl alcohols. Their associated catalytic activities complement the activities of known diaminocyclopentadienone ruthenium complexes. In particular, the substrate scope of catalytic cycloadditions with 3‐ketolactones or phloroglucinol derivatives is extended to terpenoid‐derived propargyl alcohols containing an internal alkyne moiety. A wide range of cyclic terpenoid and phloroglucinol adducts are obtained by complementary application of both types of catalysts. [ABSTRACT FROM AUTHOR]

The modular synthesis of Au(I)/Ru(II) decorated mono‐ and heterobimetallic complexes with π‐conjugated [2.2]paracyclophane is described. [2.2]Paracyclophane serves as a rigid spacer which holds the metal centers in precise spatial orientations and allows metal‐to‐metal distance modulation. A broad set of architectural arrangements of pseudo ‐geminal, ‐ortho, ‐meta, and ‐para substitution patterns were employed. Metal‐to‐metal distance modulation of Au(I)/Ru(II) heterobimetallic complexes and the innate transannular π‐communication of the cyclophanyl scaffold provides a promising platform for the investigations of structure‐activity relationship and cooperative effects. The Au(I)/Ru(II) heterobimetallic cyclophanyl complexes are stable, easily accessible, and exhibit promising catalytic activity in the visible‐light promoted arylative Meyer‐Schuster rearrangement. [ABSTRACT FROM AUTHOR]

Molybdenum alkylidyne complexes with a trisilanolate podand ligand framework ("canopy catalysts") are the arguably most selective catalysts for alkyne metathesis known to date. Among them, complex 1 a endowed with a fence of lateral methyl substituents on the silicon linkers is the most reactive, although fairly high loadings are required in certain applications. It is now shown that this catalyst decomposes readily via a bimolecular pathway that engages the Mo≡CR entities in a stoichiometric triple‐bond metathesis event to furnish RC≡CR and the corresponding dinuclear complex, 8, with a Mo≡Mo core. In addition to the regular analytical techniques, 95Mo NMR was used to confirm this unusual outcome. This rapid degradation mechanism is largely avoided by increasing the size of the peripheral substituents on silicon, without unduly compromising the activity of the resulting complexes. When chemically challenged, however, canopy catalysts can open the apparently somewhat strained tripodal ligand cages; this reorganization leads to the formation of cyclo‐tetrameric arrays composed of four metal alkylidyne units linked together via one silanol arm of the ligand backbone. The analogous tungsten alkylidyne complex 6, endowed with a tripodal tris‐alkoxide (rather than siloxide) ligand framework, is even more susceptible to such a controlled and reversible cyclo‐oligomerization. The structures of the resulting giant macrocyclic ensembles were established by single‐crystal X‐ray diffraction. [ABSTRACT FROM AUTHOR]

Performing carbonylation without the use of carbon monoxide for high‐value‐added products is an attractive yet challenging topic in sustainable chemistry. Herein, effective methods for producing linear aldehydes or alcohols selectively with formic acid as both carbon monoxide and hydrogen source have been described. Linear‐selective hydroformylation of alkenes proceeds smoothly with up to 88 % yield and >30 regioselectivity in the presence of single Rh catalyst. Strikingly, introducing Ru into the system, the dual Rh/Ru catalysts accomplish efficient and regioselective hydroxymethylation in one pot. The present processes utilizing formic acid as syngas surrogate operate simply under mild condition, which opens a sustainable way for production of linear aldehydes and alcohols without the need for gas cylinders and autoclaves. As formic acid can be readily produced via CO2 hydrogenation, the protocols represent indirect approaches for chemical valorization of CO2. [ABSTRACT FROM AUTHOR]

A novel ruthenium‐catalyzed C−H activation methodology for hydrogen isotope exchange of aromatic carbonyl compounds is presented. In the presence of catalytic amounts of specific amine additives, a transient directing group is formed in situ, which directs selective deuteration. A high degree of deuteration is achieved for α‐carbonyl and aromatic ortho‐positions. In addition, appropriate choice of conditions allows for exclusive labeling of the α‐carbonyl position while a procedure for the preparation of merely ortho‐deuterated compounds is also reported. This methodology proceeds with good functional group tolerance and can be also applied for deuteration of pharmaceutical drugs. Mechanistic studies reveal a kinetic isotope effect of 2.2, showing that the C−H activation is likely the rate‐determining step of the catalytic cycle. Using deuterium oxide as a cheap and convenient source of deuterium, the methodology presents a cost‐efficient alternative to state‐of‐the‐art iridium‐catalyzed procedures. [ABSTRACT FROM AUTHOR]

Novel arene RuII complexes containing 2,2'‐azobispyridine ligands were synthesized and characterized by using 1H and 13C NMR spectroscopy, UV/vis spectroscopy, electrochemistry, DFT calculations and single‐crystal X‐ray diffraction. Z‐configured complexes featuring unprecedented seven‐membered chelate rings involving the nitrogen atom of both pyridines were isolated and were shown to undergo irreversible isomerization to the corresponding E‐configured five‐membered chelate complexes in response to light or electrochemical stimulus. [ABSTRACT FROM AUTHOR]

The newly discovered light‐driven gem hydrogenation of alkynes opens an unconventional yet efficient entry into five‐coordinate Grubbs‐type ruthenium carbene complexes with cis‐disposed chloride ligands. Representatives of this class featuring a chelate substructure formed by an iodo‐substituted benzylidene unit react with (substituted) 2‐isopropoxystyrene to give prototypical "second‐generation" Grubbs‐Hoveyda complexes for olefin metathesis. The new approach to this venerable catalyst family is safe and versatile as it uses a triple bond rather than phenyldiazomethane as the ultimate carbene source and does not require any sacrificial phosphines. [ABSTRACT FROM AUTHOR]

An unprecedented bird‐nest high‐nuclear molybdenum(V) cobalto‐phosphate nanosized wheel modified by imidazole (im) and pyridine (py), {[H55(Mo24O48)(Co4O)2Co16(PO4)42(py)6(EtOH)2(H2O)11]‐ @[(Him)2(Hpy)]}(N‐Et‐py)(H2PO4)(py)7(EtOH)⋅12 H2O (1), has been successfully synthesized by self‐assembly. The anionic huge wheel consists of two rare {Co4O} squares, four {Co4} tetramers, four {Mo4} tetramers and four {Mo2} dimers, linked by bridging oxygen atoms and [PO4] groups and encloses two imidazolium cations and a protonated pyridium for charge balance. Surprisingly, 1 represents the first twisted wheel‐shaped cluster with a record high‐nuclear molybdenum(V) cobalto‐phosphate. The delocalized electron effects of the cluster are enhanced with the help of coordinated py ligands, which endows 1 with an excellent third‐order nonlinear optical (NLO) response. Additionally, 1 also shows a better photocatalytic water oxidation activity than Co(NO3)2 with the O2 production of 205 μmol during 6 h in the absence of the [Ru(bpy)3]2+ photosensitizer. [ABSTRACT FROM AUTHOR]

A cyclic dinuclear ruthenium(bda) (bda: 2,2'‐bipyridine‐6,6'‐dicarboxylate) complex equipped with oligo(ethylene glycol)‐functionalized axial calix[4]arene ligands has been synthesized for homogenous catalytic water oxidation. This novel Ru(bda) macrocycle showed significantly increased catalytic activity in chemical and photocatalytic water oxidation compared to the archetype mononuclear reference [Ru(bda)(pic)2]. Kinetic investigations, including kinetic isotope effect studies, disclosed a unimolecular water nucleophilic attack mechanism of this novel dinuclear water oxidation catalyst (WOC) under the involvement of the second coordination sphere. Photocatalytic water oxidation with this cyclic dinuclear Ru complex using [Ru(bpy)3]Cl2 as a standard photosensitizer revealed a turnover frequency of 15.5 s−1 and a turnover number of 460. This so far highest photocatalytic performance reported for a Ru(bda) complex underlines the potential of this water‐soluble WOC for artificial photosynthesis. [ABSTRACT FROM AUTHOR]

Noyori–Ikariya‐type ruthenium(II)‐catalysts for asymmetric transfer hydrogenation (ATH) have been known for 25 years and have proved as a well‐behaved and user‐friendly platform for the synthesis of chiral secondary alcohols. A progress has been made in the past five years in understanding the asymmetric reduction of complex ketones, where up to four stereocenters can be controlled in a single chemical transformation. Intriguing multi‐chiral molecular architectures are therefore available in few well understood and robust synthetic steps from commercially available building blocks and possess handles for additional functionalization. The aim of this Review is to showcase the availability of three‐dimensional scaffolds and homochiral lead‐like compounds via ATH and inspire their direct use in drug discovery endeavors. Basic mechanistic insights are provided to demystify the stereo‐chemical outcomes, as well as examples of diastereoselective transformations of enantiopure alcohols to give a feeling of how these rigid non‐planar molecules can be further elaborated. [ABSTRACT FROM AUTHOR]

Nitrogen‐doped mesoporous carbon nanosphere (NMCS) with tunable sizes and uniform mesoporosity was synthesized by a facile soft‐templating method. During the synthesis, F127 (PEO–PPO–PEO triblock copolymer) could be used not only as a soft template to generate the mesostructure but also as a size‐control agent to tailor the size of NMCS in a relatively wide range of 100 to 700 nm. In addition, the synthesis process was simple and suitable for large‐scale production. Moreover, the NMCS was used as support of ultrafine Ru nanoparticles (Ru/NMCS), which exhibited good catalytic performances for selective hydrogenation of quinolones. It is expected that the simple synthetic strategy for the NMCS can generate extensive interest in many catalysis and sorption applications. [ABSTRACT FROM AUTHOR]

As a novel rylene type dye a diimine ligand with a fully rigid and extended π‐system in its backbone was prepared by directly fusing a 1,10‐phenanthroline building block with 1,8‐naphthalimide. The corresponding heteroleptic ruthenium photosensitizer bearing one biipo and two tbbpy ligands was synthesized and extensively analyzed by a combination of NMR, single crystal X‐ray diffraction, steady‐state absorption and emission, time‐resolved spectroscopy and different electrochemical measurements supported by time‐dependent density functional theory calculations. The cyclic and differential pulse voltammograms revealed, that the naphthaloylenebenzene moiety enables an additional second reduction of the ligand. Moreover, this ligand possesses a very broad absorption in the visible region. In the RuII complex this causes an overlap of ligand‐centered and metal‐to‐ligand charge transfer transitions. The emission of the complex is clearly redshifted compared to the ligand emission with very long‐lived excited states lifetimes of 1.7 and 24.7 μs in oxygen‐free acetonitrile solution. This behavior is accompanied by a surprisingly high oxygen sensitivity. Finally, this photosensitizer was successfully applied for the effective evolution of singlet oxygen challenging some of the common RuII prototype complexes. [ABSTRACT FROM AUTHOR]

Although PtRu alloy nanocatalysts have been certified to possess excellent electrocatalytic performance and CO‐poisoning tolerance toward formic acid and methanol electro‐oxidation, the unaffordable usages of ruthenium (Ru) and platinum (Pt) have greatly limited their widespread adoption. Here, a facile one‐pot method is reported for implanting atomic dispersed Ru in PtNi colloidal nanocrystal clusters with different Ru/Pt/Ni molar ratios, greatly reducing the dosages of Pt and Ru, and further improving the catalytic performances for the electro‐oxidation of formic acid and methanol. Through simple control of the amount of Ni(acac)2 precursor, trimetallic Ru0.3Pt70.5Ni29.2, Ru0.6Pt55.9Ni43.5, Ru0.2Pt77.3Ni22.5, and Ru0.9Pt27.3Ni71.8 colloidal nanocrystal clusters (CNCs) are obtained. In particular, the Ru0.3Pt70.5Ni29.2 CNCs exhibit excellent specific activities for formic acid and methanol electro‐oxidation, that is, 14.2 and 15.3 times higher, respectively, than those of the Pt/C catalyst. Moreover, the Ru0.3Pt70.5Ni29.2 CNCs also possess better anti‐CO‐poisoning properties and diffusion ability than the other RuPtNi CNCs. The excellent formic acid and methanol electro‐oxidation activities of RuPtNi CNCs are ascribed to the optimal ligand effects derived from the Pt, Ni, and atomic dispersed Ru atoms, which can improve the OH adsorption ability and further the anti‐CO‐poisoning capability. This research opens a new door for increasing the electro‐oxidation properties of liquid fuels by using lower dosages of noble metals in Pt‐based catalysts. [ABSTRACT FROM AUTHOR]

Performing a heterogeneous catalysis with proteins is still a challenge. Herein, we demonstrate the importance of cross‐linked crystals for sulfoxide oxidation by an artificial enzyme. The biohybrid consists of the insertion of an iron complex into a NikA protein crystal. The heterogeneous catalysts displays a better efficiency‐with higher reaction kinetics, a better stability and expand the substrate scope compared to its solution counterpart. Designing crystalline artificial enzymes represents a good alternative to soluble or supported enzymes for the future of synthetic biology. [ABSTRACT FROM AUTHOR]

A pair of diastereomeric dinuclear complexes, [Tp′(CO)BrW{μ‐η2‐C,C′‐κ2‐S,P‐C2(PPh2)S}Ru(η5‐C5H5)(PPh3)], in which W and Ru are bridged by a phosphinyl(thiolato)alkyne in a side‐on carbon P,S‐chelate coordination mode, were synthesized, separated and fully characterized. Even though the isomers are similar in their spectroscopic properties and redox potentials, the like‐isomer is oxidized at W while the unlike‐isomer is oxidized at Ru, which is proven by IR, NIR and EPR‐spectroscopy supported by spectro‐electrochemistry and computational methods. The second oxidation of the complexes was shown to take place at the metal left unaffected in the first redox step. Finally, the tipping point could be realized in the unlike isomer of the electronically tuned thiophenolate congener [Tp′(CO)(PhS)W{μ‐η2‐C,C′‐κ2‐S,P‐C2(PPh2)S}Ru(η5‐C5H5)‐(PPh3)], in which valence trapped WIII/RuII and WII/RuIII cationic species are at equilibrium. [ABSTRACT FROM AUTHOR]

C−H hydroxylation of aryl acetamides and alkyl phenylacetyl esters was accomplished via challenging distal weak O‐coordination by versatile ruthenium(II/IV) catalysis. The ruthenium(II)‐catalyzed C−H oxygenation of aryl acetamides proceeded through C−H activation, ruthenium(II/IV) oxidation and reductive elimination, thus providing step‐economical access to valuable phenols. The p‐cymene‐ruthenium(II/IV) manifold was established by detailed experimental and DFT‐computational studies. [ABSTRACT FROM AUTHOR]

A large‐scale synthesis of known Ru olefin metathesis catalyst VII featuring an unsymmetrical N‐heterocyclic carbene (NHC) ligand with one 2,5‐diisopropylphenyl (DIPP) and one thiophenylmethylene N‐substituent is reported. The optimised procedure does not require column chromatography in any step and allows for preparation of up to 0.5 kg batches of the catalyst from simple precursors. The application profile of the obtained catalyst was studied in environmentally friendly dimethyl carbonate (DMC). Although VII exhibited low efficiency in cross‐metathesis (CM) with electron‐deficient partners, good to excellent results were noted for substrates featuring easy to isomerise C−C double bonds. This includes polyfunctional substrates of medicinal chemistry interest, such as analogues of psychoactive 5F‐PB‐22 and NM‐2201 and two PDE5 inhibitors—Sildenafil and Vardenafil. Finally, a larger scale ring‐closing metathesis (RCM) of a Vardenafil derivative was conducted in DMC, allowing for straightforward isolation of the expected product (23 g) in high yield and with low Ru contamination level (7.7 ppm). [ABSTRACT FROM AUTHOR]