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Trinuclear metallacyclic oxidovanadium(V) complexes, [{VO(L3+2R)}3] (1–3) with asymmetric multidentate linking ligands (H3L3+2R: R = H, Me, Br), were synthesized. The molecular structure of 1 is characterized as a tripod structure, with each V(V) ion coordinated by ONO-atoms from a tridentate Schiff base site and ON-atoms from a bidentate benzoxazole site of two respective H3L3+2H ligands. The intramolecular V⋯V distances range from 8.0683 to 8.1791 Å. Complex 4 is a mononuclear dioxidovanadium(V) complex, (Et3NH)[VO2(HL3+2H)]. Cyclic voltammograms of 1−3 in DMF revealed redox couples attributed to three single-electron transfer processes.

The study of the redox chemistry of mid‐actinides (U−Pu) has historically relied on cerium as a model, due to the accessibility of trivalent and tetravalent oxidation states for these ions. Recently, dramatic shifts of lanthanide 4+/3+ non‐aqueous redox couples have been established within a homoleptic imidophosphorane ligand framework. Herein we extend the chemistry of the imidophosphorane ligand (NPC=[N=PtBu(pyrr)2]−; pyrr=pyrrolidinyl) to tetrahomoleptic NPC complexes of neptunium and cerium (1‐M, 2‐M, M=Np, Ce) and present comparative structural, electrochemical, and theoretical studies of these complexes. Large cathodic shifts in the M4+/3+ (M=Ce, U, Np) couples underpin the stabilization of higher metal oxidation states owing to the strongly donating nature of the NPC ligands, providing access to the U5+/4+, U6+/5+, and to an unprecedented, well‐behaved Np5+/4+ redox couple. The differences in the chemical redox properties of the U vs. Ce and Np complexes are rationalized based on their redox potentials, degree of structural rearrangement upon reduction/oxidation, relative molecular orbital energies, and orbital composition analyses employing density functional theory. [ABSTRACT FROM AUTHOR]

A stereogenic‐at‐iron(II) catalyst scaffold is introduced which contains one coordinated meridional tridentate imidazolidin‐2‐ylidene‐functionalized 2,2′‐bipyridine, one bidentate pyrazolylpyridine, and one monodentate acetonitrile ligand. This (3+2+1)‐coordination sphere implements a stereogenic iron center. A carbon stereocenter in the N‐heterocyclic carbene moiety controls the absolute metal‐centered configuration. The bench‐stable diamagnetic iron(II) complexes can be synthesized in a highly diastereoselective fashion from iron dibromide in an efficient one‐pot coordination reaction. The obtained enantiopure complexes were applied as chiral catalysts in the ring contraction of an isoxazole to a chiral 2H‐azirine (quantitative yields, up to 90 : 10 er). [ABSTRACT FROM AUTHOR]

A new family of heteroleptic diimine‐diphosphine copper(I) complexes is reported, with six new complexes compared to benchmark [Cu(bcp)(DPEPhos)]PF6. These new complexes are based on 1,4,5,8‐tetraazaphenanthrene (TAP) ligands with representative electronic properties as well as substitution patterns and DPEPhos and XantPhos as diphosphine ligands. Their photophysical and electrochemical properties were investigated and correlated with the number and position of substituents on the TAP ligands. Stern‐Volmer studies using Hünig's base as reductive quencher demonstrated the influence of the complex photoreduction potential and of the excited state lifetime on the photoreactivity. This study refines the structure‐property relationship profile for heteroleptic copper(I) complexes and confirms that such profiles are of high interest to design new copper complexes as optimized photoredox catalysts. [ABSTRACT FROM AUTHOR]

A new C3‐symmetric tris‐imidazolium tribromide salt 3, featuring 1,3,5‐substituted triethynylbenzene, was used for the preparation of a trinuclear PdII pyridine‐enhanced precatalyst preparation stabilization and initiation‐type (PEPPSI) complex by triple C2 deprotonation followed by the addition of PdCl2. Trinuclear PdII complex possessing a combination of NHC and PPh3 ligands has also been synthesized. The corresponding mononuclear palladium(II) complexes have also been synthesized for the comparison purpose. All these complexes have been characterized by using NMR spectroscopy and ESI mass spectrometry. The molecular structure of the trinuclear palladium(II) complex bearing mixed carbene and pyridine donor ligands has been established by using single crystal XRD. All the palladium(II) complexes have been used as pre‐catalysts, which gave good to excellent yields in intermolecular α‐arylation of 1‐methyl‐2‐oxindole and Sonogashira coupling reaction. Catalytic studies indicate an enhanced activity of the trinuclear PdII complex in comparison to the corresponding mononuclear PdII complex for both catalytic transformations. The better performance of the trinuclear complex has also been further supported by preliminary electrochemical measurements. A negative mercury poison test was observed for both the aforementioned catalyses and therefore, it is likely that these organic transformations proceed homogeneously. [ABSTRACT FROM AUTHOR]

Amphotericin B has been an essential drug in the fight against leishmaniasis and fungal pathogens for decades, and has more recently gained attention for the very limited microbial resistance displayed against it. However, its toxicity has restricted its use to only the most severe cases of disease, and attempts to reduce these ill effects via formulation have had only minor success. Genetic engineering has allowed the development of superior amphotericin analogues, notably 16-descarboxyl-16-methyl amphotericin B (MeAmB), which shows a ten-fold reduction in toxicity in addition to a slight improvement in therapeutic activity. However, MeAmB is difficult to extract from its bacterial source and purify. Presented here is an alternative method of MeAmB purification. A biomimetic polymer with a high affinity for MeAmB was designed via computational modelling and synthesised. Prepared as a separation column, the polymer was able to retain the target MeAmB whilst allowing the removal of cell debris from the bacterial extract. Starting with a simple bacterial extract, the relatively simple process allowed the purification of an MeAmB salt complex at approximately 70% MeAmB, and likely higher purification from further extraction. The mean MeAmB recovery between the pre-purification extract sample and the final product was 81%. This is the first successful demonstration of extraction or purification of any amphotericin molecule with any polymeric material. The biomimetic polymer was additionally reusable and simple to fabricate, giving this technique significant advantages over traditional methods of extraction and purification of valuable compounds. [ABSTRACT FROM AUTHOR]

Polydentate ligands are used for thermodynamic stabilization of tetrylenes—low-valent derivatives of Group 14 elements (E = Si, Ge, Sn, Pb). This work shows by DFT calculations how the structure (the presence or absence of substituents) and type (alcoholic, Alk, or phenolic, Ar) of tridentate ligands 2,6-pyridinobis(1,2-ethanols) [AlkONOR]H2 and 2,6-pyridinobis(1,2-phenols) [ArONOR]H2 (R = H, Me) may affect the reactivity or stabilization of tetrylene, indicating the unprecedented behavior of Main Group elements. This enables the unique control of the type of the occurring reaction. We found that unhindered [ONOH]H2 ligands predominantly led to hypercoordinated bis-liganded {[ONOH]}2Ge complexes, where an E(+2) intermediate was inserted into the ArO-H bond with subsequent H2 evolution. In contrast, substituted [ONOMe]H2 ligands gave [ONOMe]Ge: germylenes, which may be regarded as kinetic stabilized products; their transformation into E(+4) species is also thermodynamically favorable. The latter reaction is more probable for phenolic [ArONO]H2 ligands than for alcoholic [AlkONO]H2. The thermodynamics and possible intermediates of the reactions were also investigated. [ABSTRACT FROM AUTHOR]

Three new ligands containing a bicyclo[2.2.2]oct‐7‐ene‐2,3,5,6‐tetracarboxydiimide unit have been used to assemble lantern‐type metal‐organic cages with the general formula [Cu4L4]. Functionalisation of the backbone of the ligands leads to distinct crystal packing motifs between the three cages, as observed with single‐crystal X‐ray diffraction. The three cages vary in their gas sorption behaviour, and the capacity of the materials for CO2 is found to depend on the activation conditions: softer activation conditions lead to superior uptake, and one of the cages displays the highest BET surface area found for lantern‐type cages so far. [ABSTRACT FROM AUTHOR]

The reactivity of metal‐hydride complexes can be harnessed by the modification of ancillary ligands. With the aim of improving the hydride‐donor ability of the key Mn−H intermediate and reducing steric hindrance, we herein report the rational design of a versatile and efficient NHC‐based NNC‐pincer Mn catalyst for hydrogenation reactions. This newly developed catalyst exhibited higher activity than the corresponding NNP‐pincer Mn catalyst owing to its reduced steric hindrance and enhanced Mn−H σ‐bonding orbital energy level through a π‐antibonding interaction. Using this highly active NNC‐pincer Mn catalyst, a rich array of polar unsaturated compounds (>80 examples) including esters, N‐heteroarenes, amides, carbonates, and urea derivatives, were successfully hydrogenated under relatively mild conditions. This work represents a rare example of a general phosphine‐free Mn‐catalyzed hydrogenation system. [ABSTRACT FROM AUTHOR]

One of the most effective synthetic pathways to produce unsaturated compounds and polymers, meant for both industrial and pharmaceutical applications, is olefin metathesis. These useful reactions are commonly promoted by ruthenium-based precatalysts, namely the second-generation Grubbs' catalyst (GII) and complexes bearing a styrenyl ether ligand, referred to as the second-generation Hoveyda–Grubbs' catalyst (HGII). By altering the steric and electronic characteristics of substituents on the backbone and/or on the nitrogen atoms of the NHC ligand, it is possible to increase the reactivity and stability of second-generation ruthenium catalysts. The synthesis of an HG type II complex bearing two anti-phenyl backbone substituents (anti-HGIIPh-Mes) with mesityl N-substituents is reported. The catalytic performances of the new complex were investigated in standard ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) and compared to those of the analogue complex syn-HGIIPh-Mes and to the classic HGII complex. A thorough analysis of the temperature dependence of the performances, along with a detailed comparison with the commercially available HGII, is conducted. The HGIIPh-Mes complexes are more thermally stable than their parent HGII, as shown by the fact that their activity in the ROMP of 5-ethylidene-2-norbornene does not alter when the polymerization is carried out at room temperature after the complexes have been held at 180 °C for two hours, making them particularly interesting for materials applications. [ABSTRACT FROM AUTHOR]

The combination of two different β-diketone ligands facilitates the size-controlled assembly of pure heterometallic [LnLn'Ln] linear compounds thanks to two different coordination sites present in the molecular scaffold. [HoCeHo], [ErCeEr], and [YbCeYb] analogues are presented here and are characterized both in the solid state and in solution, demonstrating the selectivity of this unique method to produce heterometallic 4f molecular entities.

Amide is one of the most widespread functional groups in organic and bioorganic chemistry, and it would be valuable to achieve stereoselective C(sp3)−H functionalization in amide molecules. Palladium(II) catalysis has been prevalently used in the C−H activation chemistry in the past decades, however, due to the weakly‐coordinating feature of simple amides, it is challenging to achieve their direct C(sp3)−H functionalization with enantiocontrol by PdII catalysis. Our group has developed sulfoxide‐2‐hydroxypridine (SOHP) ligands, which exhibited remarkable activity in Pd‐catalyzed C(sp2)−H activation. In this work, we demonstrate that chiral SOHP ligands served as an ideal solution to enantioselective C(sp3)−H activation in simple amides. Herein, we report an efficient asymmetric PdII/SOHP‐catalyzed β‐C(sp3)−H arylation of aliphatic tertiary amides, in which the SOHP ligand plays a key role in the stereoselective C−H deprotonation‐metalation step. [ABSTRACT FROM AUTHOR]

The introduction of a phenolate pendant arm in place of an acetate on AAZTA‐ and DATA‐like ligands resulted in hepta‐ and hexadentate chelators able to form Ga(III) complexes with thermodynamic stability and kinetic inertness higher than that of other Ga(III) complexes based on the parent 6‐amino‐6‐methylperhydro‐1,4‐diazepine scaffold. In particular, the heptadentate AAZ3A‐endoHB with a phenolate arm on an endocyclic N‐atom shows a logKGaL of 27.35 and a remarkable resistance to hydroxide coordination up to basic pH (pH>9). This behaviour allows to also improve the kinetic inertness of the complex showing a dissociation half‐life (t1/2) at pH 7.4 of 76 h. Although also the hexadentate AAZ2A‐exoHB chelator forms a stable (logKGaL=24.69) and inert (t1/2=33 h at pH 7.4) Ga(III) complex, the 68Ga labelling showed a better radiochemical yield with AAZ3A‐endoHB, especially at room temperature. Thus, a bifunctional chelator of AAZ3A‐endoHB was synthesized bearing an isothiocyanate group that was conjugated to the N‐terminus of a c(RGD) peptide for integrin receptor targeting. Finally, the conjugate was successfully labelled with 68Ga isotope, and the resulting radiotracer tested for its stability in human serum and then in vivo for targeting B16‐F10 tumours with miniPET imaging. [ABSTRACT FROM AUTHOR]

[Ru(bpyPO3H2)(bpy)Cl]Cl (bpyPO3H2=6,6'‐bipyridin‐2‐yl)phosphonic acid) and [Ru(tpy)(MepyPO3H2)Cl]Cl (MepyPO3H2=(pyridin‐2‐ylmethyl)phosphonic acid) were synthesized and characterized spectroscopically and electrochemically. Each compound was found to exhibit proton‐coupled electron transfer (PCET). In the case of [Ru(bpyPO3H2)(bpy)Cl]Cl, a Ru(V/IV) couple was detected at 1.4 V vs. NHE. Each complex was tested for its ability to catalyze C−H bond oxidation using a variety of sacrificial oxidants, and it was found that under aqueous conditions [Ru(bpyPO3H2)(bpy)Cl]Cl oxidizes secondary C−H bonds using sodium periodate (NaIO4) as the primary oxidant. [ABSTRACT FROM AUTHOR]

Transition-metal-catalyzed asymmetric hydrogenation (AH) is a growing field and a fundamental tool for the construction of chiral compounds. The use of earth-abundant transition metals in AH reactions remains generally limited but has received increased attention in recent years due to cost, sustainability, and environmental concerns. Here, we will summarize progress in first row transition metal catalyzed AH of minimally functionalized alkenes, including scope, mechanism, and challenges in this field. 1 Introduction 2 Ti-Catalyzed AH of Minimally Functionalized Alkenes 3 Zr-Catalyzed AH of Minimally Functionalized Alkenes 4 Co-Catalyzed AH of Minimally Functionalized Alkenes 5 Fe-Catalyzed AH of Minimally Functionalized Alkenes 6 Summary and Outlook [ABSTRACT FROM AUTHOR]

The syntheses of the first B9‐connected carboranylphosphines (B9‐Phos) featuring two carboranyl moieties as well as access to B9‐Phos ligands with bulky electron‐donating substituents, previously deemed unattainable, is reported. The electrochemical properties of the B9‐Phos ligands were investigated, revealing the ability of the mesityl derivatives to form stabilized phosphoniumyl radical cations. The B9‐Phos ligands display an extremely electron‐releasing character surpassing that of alkyl phosphines and commonly used N‐heterocyclic carbenes. This is demonstrated by their very small Tolman electronic parameters (TEPs) as well as extremely low P−Se coupling constants. Cone angles and buried volumes attest to the high steric demand exerted by the (di)carboranyl phosphines. The dicarboranyl phosphine AuI complexes show superior catalytic performance in the hydroamination of alkynes compared to the monocarboranyl phosphine analogs. [ABSTRACT FROM AUTHOR]

The reliable self‐assembly of microporous metal‐phosphonate materials remains a longstanding challenge. This stems from, generally, more coordination modes for the functional group allowing more dense structures, and stronger bonding driving less crystalline products. Here, a novel orthogonalized aryl‐phosphonate linker, 1,3,5‐tris(4'‐phosphono‐2',6'‐dimethylphenyl) benzene (H6L3) has been used to direct formation of open frameworks. The peripheral aryl rings of H6L3 are orthogonalized relative to the central aromatic ring giving a tri‐cleft conformation of the linker in which small aromatic molecules can readily associate. When coordinated to magnesium ions, a series of porous crystalline metal‐organic, and hydrogen‐bonded metal‐organic frameworks (MOFs, HMOFs) are formed (CALF‐41 (Mg), HCALF‐42 (Mg), ‐43 (Mg)). While most metal‐organic frameworks are tailored based on choice of metal and linker, here, the network structures are highly dependent on the inclusion and structure of the guest aromatic compounds. Larger guests, and a higher stoichiometry of metal, result in increased solvation of the metal ion, resulting in networks with connectivities increasingly involving hydrogen‐bonds rather than direct phosphonate coordination. Upon thermal activation and aromatic template removal, the materials exhibit surface areas ranging from 400–600 m2/g. Self‐assembly in the absence of aromatic guests yields mixtures of phases, frequently co‐producing a dense 3‐fold interpenetrated structure (1). Interestingly, a series of both more porous (530–900 m2/g), and more robust solids is formed by complexing with trivalent metal ions (Al, Ga, In) with aromatic guest; however, these are only attainable as microcrystalline powders. The polyprotic nature of phosphonate linkers enables structural analogy to the divalent analogues and these are identified as CALF‐41 analogues. Finally, insights to the structural transformations during metal ion desolvation in this family are gained by considering a pair of structurally related Co materials, whose hydrogen‐bonded (HCALF‐44 (Co)) and desolvated (CALF‐44 (Co)) coordination bonded networks were fully structurally characterized. [ABSTRACT FROM AUTHOR]

Metal‐ligand cooperation has emerged as a versatile tool for substrate activation in chemical reactivity. Herein, we provide the synthesis and characterization of a monoboranyl‐containing analogue of the ubiquitous bulky diphosphine ligand, 1,2‐bis(di‐tert‐butylphosphino)ethane, whose reactivity has been examined using nickel. Together, the pairing of nickel and boron provides a platform that allows for the cooperative coordination of organonitriles, giving unusual examples of intermolecularly bound dinickelacycles. [ABSTRACT FROM AUTHOR]

The selective forging of carbon‐boron bonds via C−H borylation stands as a central means to access fine chemical precursors. Notwithstanding, achieving selectivity in this reaction is difficult, calling for the design of molecular catalysts that offer a vector for mechanistic control. This report aims to achieve such through the strategic placement of Lewis acids in the ligand periphery, permitting engagement with a substrate through non‐covalent Lewis acid/base interactions. Various diphosphine iridium(I/III) complexes having 1,2‐bis(di‐n‐propylphosphino)ethane) (dnppe), tetrakisallylphosphinoethane (tape) and 1,2‐bis(di(3‐dicyclohexylboranyl)propylphosphino)ethane (P2BCy4) ligands were prepared. The P2BCy4 ligand scaffold boasts four Lewis acidic boron groups in its secondary coordination sphere, which are shown to engage with N‐heterocycles, tape is the precursor to P2BCy4, and dnppe is a saturated n‐propyl analogue devoid of boron functionality. Select combinations of such iridium salts/diphosphine ligands were assayed in the catalytic borylation of 2‐methylpyridine using B2Pin2 (Pin=pinacol). [ABSTRACT FROM AUTHOR]

1,4‐Diphosphabarrelenes are bicyclic diphosphines relevant, for example, for the generation of polymetallic coordination compounds. However, current synthetic protocols either suffer from low yields or require multiple reaction steps. Herein, we report the one‐step synthesis of pyrrole‐based 1,4‐diphosphabarrelenes that are obtained in very good yields from the reaction of 1,2,5‐trimethylpyrrole with 1,2‐bis(dichlorophosphino)ethane or 1,2‐bis(dichlorophosphino)benzene. The new caged diphosphines are strong donor ligands and act as bridging ligand in nickel(0), rhodium(I), iridium(I) and copper(I) coordination compounds. [ABSTRACT FROM AUTHOR]

A stereoselective total synthesis of O,N-dimethylhamatine, an analogue of an axially chiral naphthylisoquinoline natural biaryl product from tropical Ancistrocladus lianas, is reported. The route features a late-stage atropo-diastereoselective biaryl bond formation. Generation of this especially challenging, sterically hindered tetra-ortho-substituted array was achieved by using Nolan's (IPr*NHC)PdCinCl pre-catalyst under mild Negishi coupling conditions. Discussion is offered regarding the selectivity obtained experimentally and predicted from DFT calculations on the key biaryl coupling step that leads to the desired M-diastereomer.

PdII‐catalyzed C(sp3)−H activation of free carboxylic acids represents a significant advance from conventional cyclopalladation initiated reactions. However, developing a modular synthetic platform for diverse quaternary and tertiary carbon centers based on this reactivity, two challenges remain to be addressed: mono‐selectivity in each consecutive C−H functionalization step; compatibility with heteroatoms. While the exclusive mono‐selectivity was achieved by β‐lactonization/nucleophilic attack, the latter limitation remains to be overcome. Herein, we report the PdII‐catalyzed β‐ and γ‐C(sp3)−H heteroarylation of free carboxylic acids using pyridine‐pyridone ligands capable of overcoming these limitations. A sequence of three consecutive C(sp3)−H activation reactions of pivalic acid provides an unique platform for constructing diverse quaternary carbon centers containing heteroaryls which could serve as an enabling tool for escaping the flat land in medicinal chemistry. [ABSTRACT FROM AUTHOR]

A flurry of recent research has centered on harnessing the power of nickel catalysis in organic synthesis. These efforts have been bolstered by contemporaneous development of well‐defined nickel (pre)catalysts with diverse structure and reactivity. In this report, we present ten different bench‐stable, 18‐electron, formally zero‐valent nickel–olefin complexes that are competent pre‐catalysts in various reactions. Our investigation includes preparations of novel, bench‐stable Ni(COD)(L) complexes (COD=1,5‐cyclooctadiene), in which L=quinone, cyclopentadienone, thiophene‐S‐oxide, and fulvene. Characterization by NMR, IR, single‐crystal X‐ray diffraction, cyclic voltammetry, thermogravimetric analysis, and natural bond orbital analysis sheds light on the structure, bonding, and properties of these complexes. Applications in an assortment of nickel‐catalyzed reactions underscore the complementary nature of the different pre‐catalysts within this toolkit. [ABSTRACT FROM AUTHOR]

Metalloproteins activate inert molecules under mild conditions by exploiting the low‐coordinated metal centers formed in protein pockets. The creation of biomimetic metal centers using bulky ligands is an attractive strategy in bioinorganic chemistry. Herein, we report a highly bulky arenethiolato ligand containing acylamino groups that forms a neutral single‐ligand Co(II) complex. X‐ray analysis revealed that the amide NH group of the ligand was deprotonated to form an S,N‐chelate, and the cobalt center was stabilized by strong π coordination. The cobalt center exhibited a quasi‐square‐planar geometry inducing a low‐spin configuration in the solid state and in toluene, which was revealed by SQUID and ESR measurements. By contrast, Co(II)‐π coordination could be reversibly replaced by THF molecule, resulting in a high‐spin state. The novel structure was induced by the local coordination space, wherein the binding atoms were appropriately positioned, as in the hydrophobic pockets of proteins. [ABSTRACT FROM AUTHOR]

A one‐dimensional (1D) halogen‐bridged dinuclear‐metal complex (MMX‐chain) exhibits various electronic states based on a mixed‐valence metal‐dimer system. This report deals with the synthesis and physical properties of a new MMX‐chain with a bulky pendant ligand, Pt2(mcc‐HexCS2)4I (mcc‐HexCS2=trans‐4‐(methoxycarbonyl)cyclohexanedithiocarboxylate). The steric hindrance caused by the bulky substituent induces a strain in its 1D chain, achieving at ambient condition the first pure alternate charge‐polarization (ACP) state (−Pt2+−Pt3+−I−−Pt3+−Pt2+−I−−), a kind of spin‐Peierls state, as confirmed by X‐ray diffraction and its conducting and magnetic properties. The strain effect is also manifested as a very large linear thermal expansion along the chain direction, which is quite different from conventional MMX‐chains without a bulky ligand. The design of low‐dimensional materials with ligand variations is expected to lead to the emergence of new electron–lattice coupled electronic states. [ABSTRACT FROM AUTHOR]

Spatial control of reactivity is intrinsically difficult in gold catalysis due to the linear coordination mode of Au(I) and the commonly flat ligands employed for Au(III) complexes. Our recent report of a novel and sterically encumbered (NNN)diiPrAu−OH complex (Eur. J. Inorg. Chem. 2021, 3561–3564.) suggested that the (NNN) ligand framework is capable of sterically interacting with substrates through its conveniently oriented aryl groups. We have now examined these steric properties in more detail by varying the ortho‐substituent of the aryl group in (NNN)xAu−Cl complexes. With just small modifications we were able to vary the buried volume around the Cl atom and correlate this to yields obtained in a Au‐catalyzed Overman rearrangement. Computationally we further elucidate that the stark difference in yields obtained originates from a shift in binding mode of the substrate to the Au catalyst in the rate limiting step of the reaction. We thus conclude that delicate spatial control can be exercised in gold catalysis and propose the (NNN) ligand framework to be an attractive platform for the efficient design of Au(III) complexes for stereoselective catalysis. [ABSTRACT FROM AUTHOR]

Co and Fe complexes supported by a novel tetra-imine macrocycle were synthesized and characterized, and their solubility in polar organic solvents was explored. [Display omitted] The syntheses and characterization of Fe and Co complexes supported by a new tetra-imine macrocycle, TEIM (2,3,9,10-tetraethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene), are reported. Templating with Co(OAc) 2 ·4H 2 O yielded trans -[Co(TEIM)Cl 2 ][PF 6 ] (1a), which was converted to trans -[Co(TEIM)X 2 ][PF 6 ] (X = N 3 (2a) and NO 2 (3a)) through reactions with NaX (X = N 3 or NO 2). Templating with Fe generated trans -[Fe(TEIM)(NCCH 3) 2 ][PF 6 ] 2 , which was oxidized to trans -[Fe(TEIM)Cl 2 ][PF 6 ] (1b). The reaction of 1b with NaN 3 formed [Fe(TEIM)(N 3) 2 ][PF 6 ] (2b) while the reaction with [Fe(TEIM)(NCCH 3) 2 ][PF 6 ] 2 and NaNO 2 yielded trans -[Fe(TEIM)(NO 2) 2 ] (3b). Single crystal X-ray diffraction studies revealed a pseudo-octahedral geometry around the Co / Fe centers with the ethyl groups oriented above or below the plane of the TEIM ring. The absorption spectra of 1b displays weak charge transfer bands near the UV to visible region, while 2b and 3b displayed intense charge transfer bands within the visible region. Cyclic voltammograms of 1a revealed four 1 e− reductions while those of 2a and 3a display only three cathodically shifted reductions. Analogous studies of 1b and 2b revealed two 1 e- reductions while 3b displays only an oxidation event. EPR studies of ferric complexes 1b and 2b indicated a low spin d 5 electronic figuration with S = ½ ground state. [ABSTRACT FROM AUTHOR]

Using the previously designed biphenyl-2-ylphosphine ligand, featuring a remote tertiary amino group, the first gold-catalyzed intermolecular hydroalkenylation of alkynes has been developed. Synthetically valuable conjugated dienyl alcohols are formed in moderate to good yields. A range of alkenyltrifluoroborates are allowed as the alkenyl donor, and no erosion of alkene geometry and/or the propargylic configuration are detected. DFT calculations confirm the critical role of the remote basic group in the ligand as a general-base catalyst for promoting this novel gold catalysis with good efficiency.

Catalytic conversion of CO2 and hydrogen to methanol was achieved in a self‐separating multiphasic system comprising the tailor‐made complex [Ru(CO)ClH(MACHO‐C12)] (MACHO‐C12=bis{2‐[bis(4‐dodecylphenyl)phosphino]ethyl}amine) in n‐decane as the catalyst phase. Effective catalyst recycling was demonstrated for the carbonate and the amine‐assisted pathway from CO2 to methanol. The polar products MeOH or MeOH/H2O generated from the catalytic reactions spontaneously formed a separate phase, allowing product isolation and catalyst separation without the need for any additional solvent. In the amine‐assisted hydrogenation of CO2, the catalyst phase was recycled over ten subsequent runs, reaching a total turnover number to MeOH of 19200 with an average selectivity of 96 %. [ABSTRACT FROM AUTHOR]

Three molybdenum trihalogenido complexes supported by different PN3P pincer ligands were synthesized and investigated regarding their activity towards catalytic N2-to-NH3 conversion. The highest yields were obtained with the H-PN3PtBu ligand. The corresponding Mo(V)-nitrido complex also shows good catalytic activity. Experiments regarding the formation of the analogous Mo(IV)-nitrido complex lead to the conclusion that the mechanism of catalytic ammonia formation mediated by the title systems does not involve N-N cleavage of a dinuclear Mo-dinitrogen complex, but follows the classic Chatt cycle. [ABSTRACT FROM AUTHOR]

One monometallic and three bimetallic ruthenium nitrosyl (RuNO) complexes are presented and fully characterized in reference to a parent monometallic complex of formula [FTRu(bpy)(NO)]3+, where FT is a fluorenyl‐substituted terpyridine ligand, and bpy the 2,2'‐bipyridine. These new complexes are built with the new ligands FFT, TFT, TFFT, and TF‐CC‐TF (where an alkyne C≡C group is inserted between two fluorenes). The crystal structures of the bis‐RuNO2 and bis‐RuNO complexes built from the TFT ligand are presented. The evolution of the spectroscopic features (intensities and energies) along the series, at one‐photon absorption (OPA) correlates well with the TD‐DFT computations. A spectacular effect is observed at two‐photon absorption (TPA) with a large enhancement of the molecular cross‐section (σTPA), in the bimetallic species. In the best case, σTPA is equal to 1523±98 GM at 700 nm, in the therapeutic window of transparency of biological tissues. All compounds are capable of releasing NO⋅ under irradiation, which leads to promising applications in TPA‐based drug delivery. [ABSTRACT FROM AUTHOR]

In this study, dinuclear cobalt complexes (1 and 2) featuring bis(benzimidazole)pyrazolide‐type ligands (H2L and Me2L) were prepared and evaluated as molecular electrocatalysts for water oxidation. Notably, 1 bearing a non‐innocent ligand (H2L) displayed faster catalytic turnover than 2 under alkaline conditions, and the base dependence of water oxidation and kinetic isotope effect analysis indicated that the reaction mediated by 1 proceeded by a different mechanism relative to 2. Spectroelectrochemical, cold‐spray ionization mass spectrometric and computational studies found that double deprotonation of 1 under alkaline conditions cathodically shifted the catalysis‐initiating potential and further altered the turnover‐limiting step from nucleophilic water attack on (H2L)CoIII2(superoxo) to deprotonation of (L)CoIII2(OH)2. The rate–overpotential analysis and catalytic Tafel plots showed that 1 exhibited a significantly higher rate than previously reported Ru‐based dinuclear electrocatalysts at similar overpotentials. These observations suggest that using non‐innocent ligands is a valuable strategy for designing effective metal‐based molecular water oxidation catalysts. [ABSTRACT FROM AUTHOR]

The influence of the ligand backbone on the enantioselectivity in the ruthenium‐catalyzed direct asymmetric reductive amination of acetophenone with NH3 and H2, using bidentate binaphthyl‐substituted phosphine ligands, was investigated in a combined computational and experimental study. A model for the bite angle dependence of the enantiomeric excess (ee) when using diphosphines bearing binaphthyl‐groups on the P‐atoms was developed. This revealed a significant potential for increasing the enantioselectivity, if ligands with a larger bite angle than the previously reported (S,S)‐f‐binaphane are used. Suitable backbone candidates were selected from more than one million structures provided by the Cambridge Structural Database (CCDC‐CSD) and the most promising candidates were synthesized accordingly. Despite all efforts, an increase of the ee was not possible with this approach. The larger backbones resulted in the preference of different ligand coordination modes avoiding the formation of the more strongly enantiodiscriminant substrate pocket between the naphthyl wings. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Ammonia (NH3) is one of the most important industrial feedstocks in the fields of fertilizers, drugs, explosives, ordnance, commercial cleanings, and so on. However, the features of ammonia such as high toxicity and corrosivity, and difficulty in handling would inevitably increase the risk of environmental damage and the deterioration of natural/public lands. Although sorts of solid adsorbents such as metal oxides, zeolites, organic polymers, activated carbons, and metal organic frameworks have been applied in NH3 capture, they still show low uptake capacity, low affinities, and instability. Herein, we developed the first case of a highly stable sulfuric acid covalent organic framework (COF), namely TpBD‐(SO3H)2, as NH3 capturer, in which sulfonic acid sites can strongly interact with NH3 molecules, and enhance the performance of NH3 sorption. As a result, TpBD‐(SO3H)2 shows high chemical stability under strong acid and water conditions, an important merit for the potential application in harsh environment. And it also exhibits high ammonia capacity of 11.5 mmol·g−1 at 298 K and 1.0 bar, making it one of the best in all chemically stable NH3 adsorbents up to date. This work thus develops sulfuric acid COF materials as a new platform for ammonia capture and storage. [ABSTRACT FROM AUTHOR]

The sterically demanding anionic pyridine ligand [4‐(Ph3B)‐2,6‐Mes2py]− ([1]−) was used in salt metathesis reactions in order to obtain main group and transition metal complexes. Instead, reduction reactions were observed and identified as single electron transfer processes from [1]− to the respective Lewis acidic cations. The electron transfer was confirmed by reduction of the trityl cation. In order to reduce the reductive power of [1]− the borate function of the ligand was substituted with strongly electron withdrawing 3,5‐bis(trifluoromethyl)phenyl groups to give [1F]−. The redox potential was shifted from +0.56 V to +1.32 V and hence, [1F]− cannot reduce the trityl cation in contrast to [1]−. Consequently, the measured pKa value of 1F‐H (16.44) was lowered by two pKa units compared with 1‐H. Unfortunately, [1F]− still undergoes single electron transfer processes when used in salt metathesis reactions. We synthesized the anionic borane adduct [Li(THF)4][1F‐BH3] which demonstrates that [1F]− can be used as a ligand in main group chemistry. The determination of the crystal structures of [Li(THF)4][1F] and [Li(THF)4][1F‐BH3] revealed separated ion pairs while their analogs with the more electron rich [1]− are contact ion pairs. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Ammonia (NH3) is one of the most important industrial feedstocks in the fields of fertilizers, drugs, explosives, ordnance, commercial cleanings, and so on. However, the features of ammonia such as high toxicity and corrosivity, and difficulty in handling would inevitably increase the risk of environmental damage and the deterioration of natural/public lands. Although sorts of solid adsorbents such as metal oxides, zeolites, organic polymers, activated carbons, and metal organic frameworks have been applied in NH3 capture, they still show low uptake capacity, low affinities, and instability. Herein, we developed the first case of a highly stable sulfuric acid covalent organic framework (COF), namely TpBD‐(SO3H)2, as NH3 capturer, in which sulfonic acid sites can strongly interact with NH3 molecules, and enhance the performance of NH3 sorption. As a result, TpBD‐(SO3H)2 shows high chemical stability under strong acid and water conditions, an important merit for the potential application in harsh environment. And it also exhibits high ammonia capacity of 11.5 mmol·g−1 at 298 K and 1.0 bar, making it one of the best in all chemically stable NH3 adsorbents up to date. This work thus develops sulfuric acid COF materials as a new platform for ammonia capture and storage. [ABSTRACT FROM AUTHOR]

In this work, for the one-pot two-step coupling reaction of aryl halides with bis(pinacol)diboron, we first applied a phosphorus-free N,S-chelated triazole sulfide palladium-catalyzed system. At the same time, we also carried out careful ligand design to explore the effect of the environment around the coordinating sulfur atom on the reaction. Experiments have shown that the N 2-thioether substituted 1,2,3-triazlole palladium is an optimal catalyst The reaction could also reach up to quantitative yield in 4 h with only 1 mol% catalyst. Moreover, some low-activity aryl chlorides can also be coupled with bis(pinacolato)diboron under this catalytic system. We were able to obtain biaryls containing various functional groups in good to excellent yields. N,S-Chelating triazole-thioether palladium for the one-pot coupling of aryl halides with bis(pinacolato)diboron is reported for the first time. By changing the surrounding environment of the coordinating sulfur atom, we designed and synthesized oxidized and bulky thioether-substituted triazole ligands, and investigated the catalytic performance of the palladium/triazole system. [ABSTRACT FROM AUTHOR]

Au(I)/Au(III) redox catalysis, also known as redox gold catalysis, has evolved as a new technique in the past decade, opening up possibilities for the cross-coupling and 1,2-difunctioalization reactions of C–C multiple bonds that were previously inaccessible with gold(I) or gold(III) catalysis. However, the enantioselective Au(I)/Au(III) redox catalysis was missing until recently. The research group of Patil and Shi independently developed new hemilabile chiral (P,N)-ligands to achieve enantioselective redox gold catalysis for the first time. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of a small series of cyclic triimidazole derivatives functionalized with methylated pyridine or guanidine moieties is reported. These compounds were tested for their ability to bind to G‐quadruplexes from both telomeric and oncogene promoter sequences. Some of them exhibited high affinity and effective G‐quadruplex‐stabilizing properties. Overall, these compounds may represent useful leads for developing more potent and selective analogues. [ABSTRACT FROM AUTHOR]

Perfluororhodacyclopentane supported by PBP pincer ligand PBP‐RhIII(CF2)4 (2) was prepared from PBP‐RhI‐PPh3 (1) and tetrafluoroethylene (TFE). By scXRD analysis, it was revealed that the Rh−CF bond trans to the boryl ligand was largely elongated compared to the one in the apical position. Although M−CF bonds of perfluorometallacyclopentanes are known to be very stable, 2 shows high reactivity toward hydrogenolysis, iodinolysis and protonolysis, thanks to the strong trans‐effect of the highly σ‐donating boryl ligand. Analogous PCP pincer complex PCP−RhIII(CF2)4 (4) showed slower reaction rate both in oxidative cyclization with TFE and hydrogenolysis of Rh−CF bond. Catalytic production of 1,1,2,2,3,3,4,4‐octafluorobutane from two TFE and hydrogen in one pot was achieved via repetitive oxidative cyclization of TFE and Rh followed by the hydrogenolysis of Rh−CF bonds. This report demonstrates the possible application of PBP‐pincer skeleton to the preparation of fluorinated compounds from TFE. [ABSTRACT FROM AUTHOR]

Photoswitchable reagents can be powerful tools for high‐precision biological control. TRPC5 is a Ca2+‐permeable cation channel with distinct tissue‐specific roles, from synaptic function to hormone regulation. Reagents giving spatiotemporally‐resolved control over TRPC5 activity may be key to understanding and harnessing its biology. Here we develop the first photoswitchable TRPC5‐modulator, BTDAzo, to address this goal. BTDAzo can photocontrol TRPC5 currents in cell culture, as well as controlling endogenous TRPC5‐based neuronal Ca2+ responses in mouse brain slices. BTDAzos are also the first reported azo‐benzothiadiazines, an accessible and conveniently derivatised azoheteroarene with strong two‐colour photoswitching. BTDAzo′s ability to control TRPC5 across relevant channel biology settings makes it suitable for a range of dynamically reversible photoswitching studies in TRP channel biology, with the aim to decipher the various biological roles of this centrally important ion channel. [ABSTRACT FROM AUTHOR]

This perspective review shows how the coordination chemistry approach to magnetic wires based on dinuclear copper(II) complexes with rodlike aromatic oligomers (RAOs) as extended π-conjugated spacers can be extended to the design and synthesis of a novel class of metallo-carbon nanostructures (MCNs) with polycyclic aromatic hydrocarbons (PAHs) as illustrative examples of advanced magnetic nanodevices for single-molecule spintronics and quantum computing nanotechnologies. In this pursuit, two opposite but complementary ways have been explored: (i) the preparation of synthetic models through the skillful organic synthesis of tailor-made diamine-functionalized RAOs and PAHs as bridging ligands for experimental investigation of their single-molecule electron exchange (EE) and electron transport (ET) or quantum interference (QI) and quantum coherence (QC) properties, or (ii) their theoretical prediction with the aid of first-principle density functional (DFT) and time-dependent density functional (TDDFT) theories on appropriate models from chemists' creative imagination. [ABSTRACT FROM AUTHOR]

This perspective review shows how the coordination chemistry approach to magnetic wires based on dinuclear copper(II) complexes with rodlike aromatic oligomers (RAOs) as extended π-conjugated spacers can be extended to the design and synthesis of a novel class of metallo-carbon nanostructures (MCNs) with polycyclic aromatic hydrocarbons (PAHs) as illustrative examples of advanced magnetic nanodevices for single-molecule spintronics and quantum computing nanotechnologies. In this pursuit, two opposite but complementary ways have been explored: (i) the preparation of synthetic models through the skillful organic synthesis of tailor-made diamine-functionalized RAOs and PAHs as bridging ligands for experimental investigation of their single-molecule electron exchange (EE) and electron transport (ET) or quantum interference (QI) and quantum coherence (QC) properties, or (ii) their theoretical prediction with the aid of first-principle density functional (DFT) and time-dependent density functional (TDDFT) theories on appropriate models from chemists' creative imagination. [ABSTRACT FROM AUTHOR]

Despite recent advances in cluster-based catalysis for organic synthesis, the substrate scope of reactions catalyzed by metal nanoclusters is typically not superior to previously established catalytic systems. Herein, we develop new atomically precise copper nanoclusters for protosilylation, with scope expanding to alkenes and simple enynes that were not suitable for prior synthetic methodologies with traditional copper complexes. The involvement of a second copper center in the metal kernel during the migratory insertion step is thought to be responsible for the expanded scope. In addition, the reaction is highly compatible with water and can be carried out in open air rather than under inert gas protection. Mechanistic studies suggest that the cluster-catalyzed protosilylation proceeds in the absence of silyl radicals. The current findings demonstrate the potential of using metal nanoclusters for practical and sustainable chemical synthesis., (© 2024 Wiley‐VCH GmbH.)