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Azametallacyclopentadienes are an important class of metallacycles as the key intermediates in metal‐promoted or catalyzed carbon‐carbon coupling reaction of nitriles and alkynes. Rare‐earth azametallacyclopentadienes have shown various reactivity toward nitriles, depending on the substituents of nitriles. The reaction of azalutetacyclopentadienes toward 2‐methylbenzonitriles has been investigated in this work, which selectively affords the fused 7‐5‐6‐membered azalutetacycles as products. Computational studies reveal that the reaction of azalutetacyclopentadienes toward 2‐methylbenzonitriles selectively initiates with the remote activation of the benzylic C−H bond by the Lu−N bond, followed by the intramolecular nucleophilic attack from the deprotonated benzylic carbon to form a C−C bond. Subsequently, the high ring strain promoted the generation of the uncoordinated carbanion dissociated from the lutetium center, which then undergoes intramolecular nucleophilic attack toward C=N triple bond to give the final product containing fused 7‐5‐6‐membered azalutetacycle. This work not only achieves highly selective three‐step cascade reaction to form a unique class of rare‐earth metallacycle, but also provides a new idea for the transformation of unsaturated substrates with C−H bonds that can be activated. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Catalytic methylative coupling of internal alkynes and aldehydes/aldimines through regioselective oxidative cyclization promoted by a phosphine–Co complex is presented. Such process constitutes an unprecedented and unique approach for Co‐catalyzed generation of metallacycles that reversed inherent regiochemical biases to furnish a wide range of allylic alcohols and allylic amides bearing a tetrasubstituted alkene in up to 98% yield with high regioselectivity, representing a novel and general strategy for reversal of substrate‐controlled regioselectivity in metal‐catalyzed oxidative cyclization. [ABSTRACT FROM AUTHOR]

Four new Ni16 molecular wheels with the general formula [L4Ni16(RCOO)16(H2O)x(MeOH)12‐x] (where H4L=1,4‐bis((E)‐((2’‐hydroxybenzyl)imino)methyl)‐2,3‐naphthalenediol, and R=H or Me) have been isolated and structurally characterised. Complexes C1−C3 (R=Me) were formed using nickel (II) acetate and presented as polymorphs with the same formulation of charged components. The same wheel‐like architecture was observed in C4 (R=H), which was prepared using nickel (II) formate, demonstrating the potential for further versatility of the system. In contrast to similar four‐fold symmetric Ni(II) wheel clusters, measurements of the static magnetic properties of C1 indicated the presence of dominant antiferromagnetic interactions and an S=0 ground state. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of two bis(dithiolene) proligands involving heteroatomic linkers such as 1,4-dithiine and dihydro-1,4-disiline between the two protected dithiolene moieties are described. Two bimetallic complexes involving these heteroatomic bridges between two redox active bis(cyclopentadienyl)molybdenum dithiolene moieties have been synthesized and characterized by electrochemistry, spectroelectrochemistry, and their properties rationalized with (TD-)DFT. Cyclic voltammetry experiments show sequential oxidation of the two redox centers with ΔE values between successive one-electron transfers varying according to the nature of the bridge. Depending on the nature of the heteroatomic bridge, the bis-oxidized complexes exhibit either a diradical character with both radicals essentially localized on the metallacycles, or a closed-shell dicationic state. [ABSTRACT FROM AUTHOR]

A metallacyclic maltol-tethered organometallic Ir(III) half-sandwich complex was synthesized as an analog of the ruthenium anticancer complexes (RAPTA/RAED) to evaluate its in vitro antiproliferative activity against various human cancer cell lines. [ABSTRACT FROM AUTHOR]

The reaction of organoberyllium compounds with hexaphenylcarbodiphosphorane yields mono‐ortho‐beryllated complexes, which feature a double dative Be=C bond. The bonding situation in these compounds together with a simple carbodiphosphorane and an N‐heterocyclic carbene adduct was analysed with energy decomposition analysis in combination with natural orbital for chemical valence as well as with quantum theory of atoms‐in‐molecules. Furthermore, the driving forces accountable for mono‐ortho‐beryllation were elucidated along with the reactivity of the Be=C bond. [ABSTRACT FROM AUTHOR]

The synthesis of group 4 metal 1‐metallacyclobuta‐2,3‐dienes as organometallic analogues of elusive 1,2‐cyclobutadiene has so far been limited to SiMe3 substituted examples. We present the synthesis of two Ph substituted dilithiated ligand precursors for the preparation of four new 1‐metallacyclobuta‐2,3‐dienes [rac‐(ebthi)M] (M=Ti, Zr; ebthi=1,2‐ethylene‐1,10‐bis(η5‐tetrahydroindenyl)). The organolithium compounds [Li2(RC3Ph)] (1 b: R=Ph, 1 c: R=SiMe3) as well as the metallacycles of the general formula [rac‐(ebthi)M(R1C3R2)] (2 b: M=Ti, R1=R2=Ph, 2 c: M=Ti, R1=Ph, R2=SiMe3; 3 b: M=Zr, R1=R2=Ph; 3 c: M=Zr, R1=Ph, R2=SiMe3) were fully characterised. Single crystal X‐ray diffraction and quantum chemical bond analysis of the Ti and Zr complexes reveal ligand influence on the biradicaloid character of the titanocene complexes. X‐band EPR spectroscopy of structurally similar Ti complexes [rac‐(ebthi)Ti(Me3SiC3SiMe3)] (2 a), 2 b, and 2 c was carried out to evaluate the accessibility of an EPR active triplet state. Cyclic voltammetry shows that introduction of Ph groups renders the complexes easier to reduce. 13C CPMAS NMR analysis provides insights into the cause of the low field shift of the resonances of metal‐bonded carbon atoms and provides evidence of the absence of the β−C−Ti interaction. [ABSTRACT FROM AUTHOR]

We introduce the heterocumulene ligand [(Ad)NCC(tBu)]− (Ad=1‐adamantyl (C10H15), tBu=tert‐butyl, (C4H9)), which can adopt two forms, the azaalleneyl and ynamide. This ligand platform can undergo a reversible chelotropic shift using Brønsted acid‐base chemistry, which promotes an unprecedented spin‐state change of the [VIII] ion. These unique scaffolds are prepared via addition of 1‐adamantyl isonitrile (C≡NAd) across the alkylidyne in complexes [(BDI)V≡CtBu(OTf)] (A) (BDI−=ArNC(CH3)CHC(CH3)NAr), Ar=2,6‐iPr2C6H3) and [(dBDI)V≡CtBu(OEt2)] (B) (dBDI2−=ArNC(CH3)CHC(CH2)NAr). Complex A reacts with C≡NAd, to generate the high‐spin [VIII] complex with a κ1‐N‐ynamide ligand, [(BDI)V{κ1‐N‐(Ad)NCC(tBu)}(OTf)] (1). Conversely, B reacts with C≡NAd to generate a low‐spin [VIII] diamagnetic complex having a chelated κ2‐C,N‐azaalleneyl ligand, [(dBDI)V{κ2‐N,C‐(Ad)NCC(tBu)}] (2). Theoretical studies have been applied to better understand the mechanism of formation of 2 and the electronic reconfiguration upon structural rearrangement by the alteration of ligand denticity between 1 and 2. [ABSTRACT FROM AUTHOR]

We introduce the heterocumulene ligand [(Ad)NCC(tBu)]− (Ad=1‐adamantyl (C10H15), tBu=tert‐butyl, (C4H9)), which can adopt two forms, the azaalleneyl and ynamide. This ligand platform can undergo a reversible chelotropic shift using Brønsted acid‐base chemistry, which promotes an unprecedented spin‐state change of the [VIII] ion. These unique scaffolds are prepared via addition of 1‐adamantyl isonitrile (C≡NAd) across the alkylidyne in complexes [(BDI)V≡CtBu(OTf)] (A) (BDI−=ArNC(CH3)CHC(CH3)NAr), Ar=2,6‐iPr2C6H3) and [(dBDI)V≡CtBu(OEt2)] (B) (dBDI2−=ArNC(CH3)CHC(CH2)NAr). Complex A reacts with C≡NAd, to generate the high‐spin [VIII] complex with a κ1‐N‐ynamide ligand, [(BDI)V{κ1‐N‐(Ad)NCC(tBu)}(OTf)] (1). Conversely, B reacts with C≡NAd to generate a low‐spin [VIII] diamagnetic complex having a chelated κ2‐C,N‐azaalleneyl ligand, [(dBDI)V{κ2‐N,C‐(Ad)NCC(tBu)}] (2). Theoretical studies have been applied to better understand the mechanism of formation of 2 and the electronic reconfiguration upon structural rearrangement by the alteration of ligand denticity between 1 and 2. [ABSTRACT FROM AUTHOR]

We introduce the heterocumulene ligand [(Ad)NCC(tBu)]− (Ad=1‐adamantyl (C10H15), tBu=tert‐butyl, (C4H9)), which can adopt two forms, the azaalleneyl and ynamide. This ligand platform can undergo a reversible chelotropic shift using Brønsted acid‐base chemistry, which promotes an unprecedented spin‐state change of the [VIII] ion. These unique scaffolds are prepared via addition of 1‐adamantyl isonitrile (C≡NAd) across the alkylidyne in complexes [(BDI)V≡CtBu(OTf)] (A) (BDI−=ArNC(CH3)CHC(CH3)NAr), Ar=2,6‐iPr2C6H3) and [(dBDI)V≡CtBu(OEt2)] (B) (dBDI2−=ArNC(CH3)CHC(CH2)NAr). Complex A reacts with C≡NAd, to generate the high‐spin [VIII] complex with a κ1‐N‐ynamide ligand, [(BDI)V{κ1‐N‐(Ad)NCC(tBu)}(OTf)] (1). Conversely, B reacts with C≡NAd to generate a low‐spin [VIII] diamagnetic complex having a chelated κ2‐C,N‐azaalleneyl ligand, [(dBDI)V{κ2‐N,C‐(Ad)NCC(tBu)}] (2). Theoretical studies have been applied to better understand the mechanism of formation of 2 and the electronic reconfiguration upon structural rearrangement by the alteration of ligand denticity between 1 and 2. [ABSTRACT FROM AUTHOR]

We introduce the heterocumulene ligand [(Ad)NCC(tBu)]− (Ad=1‐adamantyl (C10H15), tBu=tert‐butyl, (C4H9)), which can adopt two forms, the azaalleneyl and ynamide. This ligand platform can undergo a reversible chelotropic shift using Brønsted acid‐base chemistry, which promotes an unprecedented spin‐state change of the [VIII] ion. These unique scaffolds are prepared via addition of 1‐adamantyl isonitrile (C≡NAd) across the alkylidyne in complexes [(BDI)V≡CtBu(OTf)] (A) (BDI−=ArNC(CH3)CHC(CH3)NAr), Ar=2,6‐iPr2C6H3) and [(dBDI)V≡CtBu(OEt2)] (B) (dBDI2−=ArNC(CH3)CHC(CH2)NAr). Complex A reacts with C≡NAd, to generate the high‐spin [VIII] complex with a κ1‐N‐ynamide ligand, [(BDI)V{κ1‐N‐(Ad)NCC(tBu)}(OTf)] (1). Conversely, B reacts with C≡NAd to generate a low‐spin [VIII] diamagnetic complex having a chelated κ2‐C,N‐azaalleneyl ligand, [(dBDI)V{κ2‐N,C‐(Ad)NCC(tBu)}] (2). Theoretical studies have been applied to better understand the mechanism of formation of 2 and the electronic reconfiguration upon structural rearrangement by the alteration of ligand denticity between 1 and 2. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Metalla‐isosilabenzenes and metalla‐isogermabenzenes have been successfully synthesized by the formal [5+1]‐cycloaddition of diethynylsilane or diethynylgermane with simple metal complexes. This is the first example of a heavier Group 14 metalla‐isobenzene isomer bearing a cumulative double bond motif within a metallacycle. These novel complexes were fully characterized by NMR spectroscopy and single‐crystal X‐ray diffraction analysis. The stabilization of the cyclic metal‐vinylidene complexes has been analyzed using density functional theory (DFT) calculations. When the metalla‐isosilabenzenes bearing Si—H bond were treated with the trityl salt as a hydride scavenger, the formation of silylium cation was observed spectroscopically. Both of metalla‐isosilabenzenes and metalla‐isogermabenzenes can readily undergo migratory insertion reactions to furnish siloles or germoles. [ABSTRACT FROM AUTHOR]

'Transient' C−H functionalization has emerged in recent years to describe the use of a dynamic linkage, often an imine, to direct cyclometallation and subsequent functionalization. As the field continues to grow in popularity, we consider the features that make an imine directing group transient. A transient imine should be i) formed dynamically in situ, ii) avoid discrete introduction or cleavage steps, and iii) offer the potential for catalysis in both the directing group and metal. This concept article contrasts transient imines with pioneering early studies of imines as directing groups for the formation of metallacycles and the use of preformed imines in C−H functionalization. Leading developments in the use of catalytic additives to form transient directing groups (as aldehyde or amine) are covered including selected highlights of the most recent examples of catalytic imine directed C−H functionalization with transition metals. [ABSTRACT FROM AUTHOR]

This work reports on a novel family of silver metallogels based on discrete coordination complexes. Structurally, they consist of dendrimers containing a trinuclear silver metallacycle at the core, with the general formula [M(μ-pz)]3, and poly(benzyl)ether branched structures with different numbers or terminal alkoxy chains at the periphery. These silver metallodendrimers are able to gel low-polarity solvents such as dodecane or cyclohexane, giving rise to luminescent organogels at room temperature with the property of aggregation-induced emission (AIE). This property means that in solution or the sol state, they are weak emitters, but in the gel state, luminescence is considerably increased. In this particular case, they exhibit blue luminescence. Two different dendritic scaffolds have been studied, finding significant differences in solubility, gel formation and dependence of luminescence on temperature. The results show that properly tailored silver gelators can show luminescence in the gel state. [ABSTRACT FROM AUTHOR]

The development of artificial light‐harvesting systems mimicking the natural photosynthesis method is an ever‐growing field of research. Numerous systems such as polymers, metal complexes, POFs, COFs, supramolecular frameworks etc. have been fabricated to accomplish more efficient energy transfer and storage. Among them, the supramolecular coordination complexes (SCCs) formed by non‐covalent metal‐ligand interaction, have shown the capacity to not only undergo single and multistep energy migration but also to utilize the harvested energy for a wide variety of applications such as photocatalysis, tunable emissive systems, encrypted anti‐counterfeiting materials, white light emitters etc. This review sheds light on the light‐harvesting behavior of both the 2D metallacycles and 3D metallacages where design ingenuity has been executed to afford energy harvesting by both donor ligands as well as metal acceptors. [ABSTRACT FROM AUTHOR]

Amino imidazoline‐2‐imines (AmIm) are a new class of chelating, monoanionic N,N'‐donor ligands stronger than the analogous β‐diketiminate ligands and give rise to five‐membered metallacycles. The coordination chemistry of the monoanionic ligands 1,2‐NHC=N−C6H4−NDipp− (i), cis‐1,2‐NHC=N−CMe=CMe−NDipp− (ii) was towards magnesium was investigated with the focus on the stabilization of low‐valent magnesium(I) species, NHC=cyclo‐C(NiPr2CMe)2, Dipp=2,6‐iPrC6H3. Both ligand systems (i) and (ii) form heteroleptic magnesium iodide species with were subjected to reduction. The complex [Mg(1,2‐NHC=N−C6H4−NDipp)]2 was found to be insoluble, which prevented further purification. In contrast, the yield of the analogous complex [Mg(cis‐1,2‐NHC=N−CMe=CMe−NDipp)]2 was very low. As a significant side product the homoleptic complex [Mg(cis‐1,2‐NHC=N−CMe=CMe−NDipp)2] was identified. [ABSTRACT FROM AUTHOR]

Reaction of [VO(OR)3] (R = Et, nPr) with 2,2′-diphenylglycine afforded the alkoxide-bridged dimers {[VO(OR)(μ-OR)][Ph2C(NH2)(CO2)]}2, whereas use of benzilic acid, in the presence of alkali metals, afforded 16-membered metallocycles {V8(O)4M(OR)8[Ph2C(OH)(CO2)]12} (M = <1 Na, K). For the ring systems, magnetic susceptibility data is consistent with mixed-valence vanadium with an average oxidation state of 3.5. The dimer and ring systems are capable of the ring opening polymerisation (ROP) of ε-caprolactone under N2, air, or as melts affording mostly low to medium molecular weight cyclic and linear products. [ABSTRACT FROM AUTHOR]

Owing to their capacity for dynamically linking two or more functional molecules, supramolecular coordination complexes (SCCs), exemplified by two-dimensional (2D) metallacycles and three-dimensional (3D) metallacages, have gained increasing significance in biomedical applications. However, their inherent hydrophobicity and self-assembly driven by heavy metal ions present common challenges in their applications. These challenges can be overcome by enhancing the aqueous solubility and in vivo circulation stability of SCCs, alongside minimizing their side effects during treatment. Addressing these challenges is crucial for advancing the fundamental research of SCCs and their subsequent clinical translation. In this review, drawing on extensive contemporary research, we offer a thorough and systematic analysis of the strategies employed by SCCs to surmount these prevalent yet pivotal obstacles. Additionally, we explore further potential challenges and prospects for the broader application of SCCs in the biomedical field. [ABSTRACT FROM AUTHOR]

Utilizing rhodium complexes to catalyze 2‐vinylbenzaldehyde derivatives has proven to be a valuable strategy in constructing indanone moieties. In this study, the stoichiometric reactions of Wilkinson's catalyst RhCl(PPh3)3 with 2‐vinylbenzaldehyde derivatives were investigated, leading to the formation of rhodaindanone complexes (2). Notably, the transformation of of rhoda‐1‐indanone (2 a) to rhoda‐2‐indanone (3) was achieved for the first time. In comparision, the reactivity of IrCl(PPh3)3 and Ir(CO)(CH3CN)(PPh3)2 ⋅ BF4 towards 2‐vinylbenzaldehyde derivatives affords irida‐2‐indanone complexes (4) and fused iridacycles (5), respectively. These newly prepared coumpounds represent the first metellacycles resulting from the reactions between 2‐vinylbenzaldehyde derivatives and rhodium/iridium complexes and may provide further insights into the catalytic processes involving 2‐vinylbenzaldehyde derivatives for synthesizing indanone compounds. [ABSTRACT FROM AUTHOR]

Bacterial infections can lead to the development of large-scale outbreaks of diseases that pose a serious threat to human life and health. Also, conventional antibiotics are prone to producing resistance and allergic reactions, and their therapeutic effect is dramatically diminished when bacterial communities form biofilms. Fortunately, well-designed supramolecular coordination complexes (SCCs) have been used as antibacterials or anti-biofilms in recent years. SCCs can kill bacteria by directly engaging with the bacterial surface through electrostatic interactions or by penetrating the bacterial membrane through the auxiliary effect of cell-penetrating peptides. Furthermore, scientists have engineered fluorescent SCCs that can produce reactive oxygen species (ROS) to eliminate bacteria when exposed to laser irradiation, and they also demonstrate outstanding performance in in vivo imaging, enabling integrated diagnosis and treatment. In this review, we summarize the design strategy and applications of SCCs in antibacterials or anti-biofilms and provide an outlook on future research. [ABSTRACT FROM AUTHOR]

A family of dinuclear complexes was rationally designed to bind to two neighboring phosphate diesters of DNA by molecular recognition. Although these complexes bind strongly and irreversibly to DNA and induce apoptosis in cancer cells, a direct proof of the intended binding mode is missing. To mimic two neighboring phosphate diesters of DNA, we use here the dicarboxylate glutarate as a difunctional ligand. Starting from the acetate‐bound CuII2 complex, protonation results in the de‐coordination of acetate and allows the synthesis of the glutarate‐bound complex. Instead of bridging two CuII ions of one dinuclear complex, two glutarates bridge two dinuclear complexes resulting in a tetranuclear metallo‐macrocycle. The molecular structures of two different salts differ in the square‐pyramidal coordination to the CuII ions. The carboxylate stretching modes, the d‐d and the CT transtitions are not sensitive enough to resolve these differences. The exchange coupling is weakly antiferromagnetic between the CuII ions in the dinuclear subunits and negligible between the subunits via the glutarates. The consequences for suited ligands to model the binding to two neighboring phosphate diesters in the DNA backbone is discussed. [ABSTRACT FROM AUTHOR]

Aromatic metalla‐annulenes are important aromatic compounds, research into which has been mainly concentrated on metal‐benzenes and their lower homologues. Reports on their superior homologs are rare, and this has greatly limited the systematic study of their properties. In this work, a series of osma‐dehydro[11]annulenes with good air and thermal stability were prepared in high yields through a simple [10+1] strategy, by incorporating a metal fragment into conjugated ten‐carbon chains in a one‐pot reaction. They are the first monometallic aromatic metalla‐[n]annulenes with the ring size larger than 6, and their Craig‐Hückel hybrid aromaticity is supported by various physical and computational parameters. Besides, these complexes show versatile reactivities, not only giving further evidence for their aromaticity, but also demonstrating their physical and chemical properties can easily be regulated. This work enriches the metalla‐aromatic chemistry, and provides a new avenue for the synthesis of large metalla‐annulenes with different ring sizes. [ABSTRACT FROM AUTHOR]

Manganese(I) carbonyl complexes bearing a MACHO‐type ligand (HN(CH2CH2PR2)2) readily react in their amido form with CO2 to generate 4‐membered {Mn−N−C−O} metallacycles. The stability of the adducts decreases with the steric demand of the R groups at phosphorous (R=isopropyl>adamantyl). The CO2‐adducts display generally a lower reactivity as compared to the parent amido complexes. These adducts can thus be interpretated as masked forms of the active amido catalysts and potentially play important roles as off‐loop species or branching points in catalytic transformations of carbon dioxide. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Metallacyclopentadienes are important metallacycles and regarded as intermediates in many reactions, therefore, new methods to achieve them are anticipated. In this study, a formal [3+2] method, through the reactions of an osmapentalyne with benzyl carbanions, was developed. The reactions underwent a nucleophilic attack of carbanions to the Os≡C bond, followed by C—H activation to form the five‐membered osmacyclopentadiene ring. Most of the reactions were carried out at room temperature, the substituents on the aromatic rings of benzyl carbanions are diverse, and the resulting products contain an Os—H bond, representing a novel type of 10C‐carbolong complexes. This work provides a new convenient route to construct metallacyclopentadienes, which is expected to further promote the development of such a type of substances. [ABSTRACT FROM AUTHOR]

A series of polynuclear, dinuclear, and mononuclear Mo(VI) complexes were synthesized with the hydrazonato ligands derived from 5-methoxysalicylaldehyde and the corresponding hydrazides (isonicotinic hydrazide (H2L1), nicotinic hydrazide (H2L2), 2-aminobenzhydrazide (H2L3), or 4-aminobenzhydrazide (H2L4)). The metallosupramolecular compounds obtained from non-coordinating solvents, [MoO2(L1,2)]n (1 and 2) and [MoO2(L3,4)]2 (3 and 4), formed infinite structures and metallacycles, respectively. By blocking two coordination sites with cis-dioxo ligands, the molybdenum centers have three coordination sites occupied by the ONO donor atoms from the rigid hydrazone ligands and one by the N atom of pyridyl or amine-functionalized ligand subcomponents from the neighboring Mo building units. The reaction in methanol afforded the mononuclear analogs [MoO2(L1-4)(MeOH)] (1a–4a) with additional monodentate MeOH ligands. All isolated complexes were tested as catalysts for cyclooctene epoxidation using tert-butyl hydroperoxide (TBHP) as an oxidant in water. The impact of the structure and ligand lability on the catalytic efficiency in homogeneous cyclooctene epoxidation was elucidated based on theoretical considerations. Thus, dinuclear assemblies exhibited better catalytic activity than mononuclear or polynuclear complexes. [ABSTRACT FROM AUTHOR]

Tumor hypoxia severely limits the therapeutic efficacy of photodynamic therapy (PDT) for solid tumors, which is highly dependent on tissue oxygen concentration. In this study, we developed a platinum(II)-acetylide-based metallacycle compound bearing six 1,4-dimethylnaphthalenes (DMN) groups, and controlled the photodynamic and photothermal effects of the compound by adjusting the power of 730 nm laser to achieve reversible sensitization, storage and release of 1O2 within a single molecule. The compound formed nanoparticles by self-assembly and exhibited good water solubility and biocompatibility. Under laser irradiation, the strong spin-orbit coupling of platinum atoms in the metallacycle facilitated 1O2 generation. The produced 1O2 was captured by the DMN carriers and transported into the hypoxic tumor, where 1O2 release was triggered owing to the good photothermal effect of the extended conjugation of the metallacycle. During therapy, the metallacycle serving as a photosensitizer, 1O2 carrier, and photothermal reagent, achieved the synergistic therapy of PDT/PTT, demonstrating the versatility of the metallacycle. This study proposes a new strategy to develop phototherapy agents that are suitable for hypoxic tumors. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Metallacyclopentadienes are important metallacycles and regarded as intermediates in many reactions, therefore, new methods to achieve them are anticipated. In this study, a formal [3+2] method, through the reactions of an osmapentalyne with benzyl carbanions, was developed. The reactions underwent a nucleophilic attack of carbanions to the Os≡C bond, followed by C—H activation to form the five‐membered osmacyclopentadiene ring. Most of the reactions were carried out at room temperature, the substituents on the aromatic rings of benzyl carbanions are diverse, and the resulting products contain an Os—H bond, representing a novel type of 10C‐carbolong complexes. This work provides a new convenient route to construct metallacyclopentadienes, which is expected to further promote the development of such a type of substances. [ABSTRACT FROM AUTHOR]

A metallacyclic maltol-tethered organometallic Ir(III) half-sandwich complex was synthesized as an analog of the ruthenium anticancer complexes (RAPTA/RAED) to evaluate its in vitro antiproliferative activity against various human cancer cell lines.

The motivation for making heterometallic compounds stemmed from their emergent synergistic properties and enhanced capabilities for applications. However, the atomically precisely controlled synthesis of heterometallic compounds remains a daunting challenge of the complications that arise when applying several metals and linkers. Herein, a stepwise and controlled method is reported for the accurate addition of second and third metals to homometallic aluminum macrocycles based on the synergistic coordination and hard‐soft acid‐base theory. These heterometallic compounds showed a good Lewis acid catalytic effect, and the addition of hetero‐metals significantly improved the catalytic effect and rate, among that the conversion rate of compound AlOC‐133 reached 99.9% within half an hour. This method combines both the independent controllability of stepwise assembly with the universality of one‐step methods. Based on the large family of clusters, the establishment of this method paves the way for the controllable and customized molecular‐level synthesis of heterometallic materials and creates materials customized for preferential application. [ABSTRACT FROM AUTHOR]

[Display omitted] It is still challenging to develop multi–step cascaded artificial light–harvesting systems (ALHSs) with tunable efficiency. Here, we designed novel cascaded ALHSs with AIE–active metallacycles as the light–harvesting antenna, Eosin Y (ESY) and sulforhodamine 101 (SR101) as conveyors, near–infrared emissive chlorin–e6 (Ce6) as the final acceptor. The close contact and fair spectral overlap between donor and acceptor molecules at each level ensured the efficient sequential three–step energy transfer. The excited energy was sequentially and efficiently funneled to Ce6 along the cascaded line MTPEPt1 → ESY → SR101 → Ce6. Additionally, a unique strategy for regulating the efficiency of ALHS was illustrated by adjusting hydrophilic and hydrophobic interactions. [ABSTRACT FROM AUTHOR]

Multifunctional metallacycles with solid-state emission are highly important in cancer therapy. Here, an aggregation-induced emission (AIE)-active metallacycle of DTPABT-MC-R is developed with efficient emission in the NIR region in the solid state (PLQYs = 4.92%). DTPABT-MC-R-based nanoparticles also display excellent photo-stability, and impressive photosensitive characteristics (ROS efficiency = 10.74%), finally leading to applications in cellular imaging and photodynamic therapy (PDT). [ABSTRACT FROM AUTHOR]

The yttrium gallabenzene complex [(1‐Me‐3,5‐tBu2−C5H3Ga)(μ‐Me)Y(2,4‐dtbp)] is accessible from Y(GaMe4)3 and K(2,4‐dtbp) via a tandem salt metathesis/methane elimination (2,4‐dtbp=2,4‐di‐tert‐butyl‐pentadienyl). The pentadienyl ligand in [(1‐Me‐3,5‐tBu2−C5H3E)(μ‐Me)Y(2,4‐dtbp)] (E=Al, Ga) is easily displaced by salt metathesis with KC5Me5 and KTpMe,Me (TpMe,Me=tris(pyrazolyl‐Me2‐3,5)borato) affording [(1‐Me‐3,5‐tBu2−C5H3E)(μ‐Me)Y(TpMe,Me)] and [(1‐Me‐3,5‐tBu2−C5H3E)(μ‐Me)Y(C5Me5)]. The yttrium center in [(1‐Me‐3,5‐tBu2−C5H3E)(μ‐Me)Y(2,4‐dtbp)] readily forms adducts with neutral Lewis bases like 4‐DMAP (4‐dimethylaminopyridine), PMe3, DMPE (1,2‐bis(dimethylphosphino)ethane), and DME (1,2‐dimethoxyethane). In stark contrast, addition of TMEDA (N,N,N',N'‐tetramethylethylenediamine) results in methyl/pentadienyl exchange between aluminum and yttrium resulting in [(1‐(2,4‐dtbp)‐1‐Me‐3,5‐tBu2−C5H3Al)Y(Me)(tmeda)]. The bonding features of the newly synthesized complexes are analyzed by single‐crystal X‐ray diffraction (SCXRD) and heteronuclear (89Y, 31P) NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The preparation of materials having optical properties is a fertile area of research because of their application in OLEDs, sensors, and semiconducting materials science field. Moreover, considering environmental concerns, there is an increasing need in the scientific community to enhance the preparative methods using eco-friendly approaches. In this work, the mechanochemical liquid assisted grinding (LAG) method is applied for the syntheses of hybrid organometallic/organic materials made of π–acidic silver(I) or copper(I) metallacycles, with bridging ligands such as 3,5-bis(trifluoromethyl)pyrazolate or 3,5-dinitro-pyrazolate, and coronene, a highly symmetric polycyclic aromatic molecule (PAH). The LAG method was monitored by FT-IR spectroscopy and SEM; the former was applied to study the slight structural modification upon interactions, and the latter was used to depict the changes in the solid surface morphology upon CH2Cl2-assisted grinding. On the other hand, the dissolution of the materials reversibly yields the starting compounds. The stacked materials were characterized by elemental and TGA analyses, and photoluminescence (PL), and IR spectroscopies. The PL study highlights the room temperature quenching of the coronene emissions at 505 nm, indicating the occurrence of dispersive electrostatic interactions. Interestingly, the solid-state UV-Vis study allowed the calculations of direct (2.27 eV) and indirect (2.78 eV) band gaps for the D/A adduct {[3,5-(CF3)2pz]Ag}3@coronene, 1, with values featuring the materials in the semiconductor band gap range, useful for application in OFETs or OPVs. [ABSTRACT FROM AUTHOR]

Mixed-ligand tetranuclear supramolecular coordination complexes (SCCs) of Pt(II)-p-biphenyl and bridging ligands derivatives of 4,4′-bypiridine (8)–(10), were synthesized and characterized. The SCCs were synthesized stepwise, starting from the Pt-p-biphenyl -Pt core. The crystal structure of complex {[Pt(2,2′-bpy)]4(μ-bph)2(μ-(4,4′-bpy)2}{PF6}4 (2,2′-bpy = 2,2′-bipyridine, bph = p-biphenyl and 4,4′-bpy = 4,4′ bipyridine), was determined using single-crystal diffraction methods. The emission profile of the tetranuclear complexes (8)–(10) was influenced by the length of the bridging ligands and was found to depend on solvent polarity. Dual-emission patterns in methanol–water mixtures were observed only in the cases of complexes (9) and (10), attributed to aggregation-induced emission phenomena. [ABSTRACT FROM AUTHOR]

Metal-mediated N–H and C–H bond activation of aliphatic amines is an effective strategy for synthesizing biologically important molecules. Ln (Ln = La and Ce) atom reactions with dimethylamine are carried out in a pulsed-laser vaporization supersonic molecular beam source. A series of dehydrogenation species are observed with time-of-flight mass spectrometry, and the dehydrogenated Ln-containing species in the formula Ln(CH2NCH3) are characterized by single-photon mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical calculations. The theoretical calculations include density functional theory for both Ln species and multiconfiguration self-consistent field and quasi-degenerate perturbation theory for the Ce species. The MATI spectrum of La(CH2NCH3) consists of a single vibronic band system, which is assigned to the ionization of the doublet ground state of N-methyl-lanthanaaziridine. The MATI spectrum of Ce(CH2NCH3) displays two vibronic band systems, which are attributed to the ionization of two-pair lowest-energy spin–orbit coupling states of N-methyl-ceraaziridine. Both metallaaziridines are three-membered metallacycles and formed by the thermodynamically and kinetically favorable concerted dehydrogenation of the amino group and one of the methyl groups. [ABSTRACT FROM AUTHOR]

Thanks to supramolecular interactions of macrocyclic compounds with their guest ions or molecules, macrocycles have found wide applications in molecular and chiral recognition, separation, transportation, molecular machines, and so on. Photoswitchable macrocycles are especially appealing and attracting more and more interest because the embedded molecular photoswitch enables dynamic control of molecular shape, conformation, and different properties by light, a non‐invasive, remote and highly tunable stimulus. With available photochromic compounds, various photoswitchable macrocycles have been developed. In this review paper, we describe the recently reported photoswitchable macrocyclic compounds, with a focus on the control of the macrocyclic structure, dynamic, photo or thermal isomerization, as well as their applications on encapsulation and release of ionic or aromatic species, on the reversible modulation of chemical, biological, electronic, fluorescent and chiroptical properties by light. [ABSTRACT FROM AUTHOR]

In this work we report a new PbII coordination polymer [Pb3L2(N3)4] n , which was obtained from Pb(N3)2 and 1-(pyridin-2-yl)ethylidenepicolinohydrazide (HL). The complex exhibits a 1D polymeric chain, constructed from the {[Pb3(N3)4]2+}n backbone, decorated with deprotonated organic L− ligands. The latter ligands are pentadentate and link two metal cations. The PbII ions were found to be in a N5O or N5O2 coordination environment, formed by covalent bonds. The azide ligands either bind four metals in a μ4-1,1,3,3 coordination mode or are coordinated to metal centers as terminal ligands. All the metal centers exhibit a hemidirected coordination geometry with a pronounced coordination gap, which allows the close approach of an additional nitrogen atom arising from an adjacent terminal azide ligand. A simplified underlying network of [Pb3L2(N3)4] n , without considering Pb⋯N tetrel bonds, exhibits the tetranodal 3,4,4,4-connected chain topology, while considering all Pb⋯N tetrel bonds, the binodal 4,5-connected chain topology was shown. The crystal packing of [Pb3L2(N3)4] n is reinforced by intermolecular π⋯π stacking interactions, formed by PbII-based five-membered chelate metallocycles and pyridine rings. In-depth bonding analysis using ETS-NOCV, IQA and NCI methods demonstrates that although the azide anions experience significant steric crowding due to repulsive azide–azide interactions, they are engaged in strong attractive, Coulomb dominated, dative-covalent Pb–N and tetrel-type Pb⋯N connections, which are further augmented by weak exchange–correlation driven C–H⋯N hydrogen bonds as well as London dispersion forces due to metallocycle units. The diffuse reflectance spectrum of [Pb3L2(N3)4] n revealed a broad band with two maxima in the UV region, corresponding to intraligand transitions, and an intense shoulder in the visible region, corresponding to metal-to-ligand charge-transfer. The latter shoulder explains the observed yellow colour of the complex. [ABSTRACT FROM AUTHOR]

Herein, a new tellurium and mercury containing mercuraazametallamacrocycle has been prepared via (2+2) condensation of bis(o‐aminophenyl)telluride and bis(o‐formylphenyl)mercury(II). The isolated bright yellow solid of mercuraazametallamacrocycle has adopted unsymmetrical figure‐of‐eight conformation in the crystal structure. To study the metallophilic interactions between closed shell metal ions, the macrocyclic ligand has been treated with two equiv. of AgOTf (OTf=trifluoromethansulfonate) and AgBF4, which afforded greenish‐yellow bimetallic silver complexes. The isolated silver complexes displayed intramolecular Hg⋅⋅⋅Ag, Te⋅⋅⋅Ag interactions as well as intermolecular Hg⋅⋅⋅Hg interactions and formed an extended 1D molecular chain by directing six atoms to interact as TeII⋅⋅⋅AgI⋅⋅⋅HgII⋅⋅⋅HgII⋅⋅⋅AgI⋅⋅⋅TeII in a non linear fashion. The Hg⋅⋅⋅Ag, Te⋅⋅⋅Ag interactions have also been studied in solution by 199Hg, 125Te NMR spectroscopy, absorption, and emission spectroscopy. In DFT calculations, the Atom in Molecule (AIM) analysis, non‐covalent interactions (NCI), natural bonding orbital (NBO) analysis strongly supported for experimental evidences and revealed that the intermolecular Hg⋅⋅⋅Hg interaction is stronger than the intramolecular Hg⋅⋅⋅Ag interactions. [ABSTRACT FROM AUTHOR]

By using 2-(9-phenanthryl)pyridine (phpyr) and its derivatives as cyclometalated ligands, we synthesized a set of isomeric red-emitting complexes Ir(phpyr-R)2tmd (R = –H, –CF3, –F and –CH3, tmd = 2,2,6,6-tetramethylheptane-3,5-dione) with different coordinated modes, including bis-five-membered and five- + six-membered Ir-(C^N) ring chelating modes. The latter are the first examples of hetero-coordinated Ir(C^N)2(L^X)-type complexes containing both five- and six-membered Ir-(C^N) metallocycles. Their coordination geometries were distinctly determined using X-ray crystallographic analysis. Compared to typical bis-five-membered ring-chelated complexes, these novel hetero-coordinated isomers show bathochromic emission and lower quantum yields. On careful analysis of their electrochemical behavior and DFT calculations, it has been found that the regulatory effects of the solitary six-membered metallocycles in Ir(phpyr-R)2tmd could not only stabilize the LUMO but also destabilize the HOMO, leading to a narrower energy gap. More importantly, DFT calculations of the relative energies of these isomeric complexes demonstrated that bis-five-membered and five- + six-membered chelating modes are more stable compared to bis-six-membered rings, consistent with experiments. This work provides guidance for the structural design of Ir(C^N)2(L^X)-type complexes. [ABSTRACT FROM AUTHOR]

Benzene‐1,2,4,5‐tetrathiolate (btt) has been used as a bridging ligand to prepare a redox active (molybdenocene dithiolene)‐based bimetallic complex Cp2Mo(btt)MoCp2, which exhibits four successive electron transfers up to the tetracation. Spectro‐electrochemical investigations together with DFT and TD‐DFT calculations evidence that the two electroactive MoS2C2 metallacycles are electronically coupled in the monocationic as in the dicationic state. Two salts of the dication [Cp2Mo(btt)MoCp2]2+ have been structurally characterized with PF6− and HSO4− counterions, showing different chair or boat conformations associated with variable folding angles of the two MoS2C2 metallacycles along the S−S hinge. The bis‐oxidized dicationic complex exhibits a diradical character, with both radicals essentially localized on the metallacycles and with antiferromagnetic coupling evidenced from magnetic susceptibility measurements. [ABSTRACT FROM AUTHOR]

This paper covers Pt(II) complexes of the compositions Pt(η3-P1C1C2)(Y) (Y = NL or I) and Pt(η3-P1C1N1)(Y), Y = OL, NL, CL, Cl or Br). These complexes crystallized in four crystal classes: monoclinic (9 examples), triclinic (3 examples), orthorhombic (3 examples), and tetragonal (2 examples). The structural parameters (Pt-L, L-Pt-L) are analyzed and discussed with attention to the distortion of square-planar geometry about the Pt(II) atoms and trans-influence. These data are compared and discussed with those of Pt(η3-P1N1N2)(Y), Pt(η3-P1N1X1)(Y), (X1=O1, C1, S1, Se1), Pt(η3-N1P1N2)(Cl), Pt(η3-S1P1S2)(Cl), Pt(η3-P1S1Cl1)(Cl), and Pt(η3-P1Si1N1)(OL) types. Each heterotridentate ligand creates two metallocyclic rings with a common central ligating atom. These η3-ligands form twenty-three types of metallocycles and differ by the number and type of the atoms involved in the metallocyclic rings. [ABSTRACT FROM AUTHOR]

Metallacyclobutanes are intermediates in several catalytic cycles such as olefin metathesis and cyclopropanation. Furthermore, nickel is attracting attention as a versatile, earth‐abundant metal in developing new homogeneous catalytic transformations. In this context, the current literature on nickelacyclobutanes and their role in catalysis is reviewed. First, catalytic reactions involving a (putative) nickelacyclobutane intermediate are discussed, including cyclopropanations and various transformations of methylenecyclopropane. Second, studies of the stoichiometric reactivity of nickelacyclobutanes relying on their direct observation or even isolation are detailed. In particular, the relationship between the structure of nickelacyclobutanes and their reactivity is highlighted. Finally, future prospects for the development of new catalytic transformations relying on nickelacyclobutane intermediates are briefly outlined. [ABSTRACT FROM AUTHOR]

A novel flexible tripyridyl disulfide ligand (L, 2,6-bis(4-pyridinesulfanylmethyl)pyridine) having a pyridyldithioether backbone was synthesized and its diverse types of one-dimensional (1D) coordination polymers (1–4) with coinage metal (copper and silver) salts were isolated. The complexation with copper(II) nitrate afforded a loop chain type product {[Cu(L)2(NO3)2]·CH2Cl2}n (1), in which twisted Cu2L2 metallacycles in an S-configuration of L share one copper(II) node. The complexations with silver(I) salts (X = NO3−, PF6−, and ClO4−) resulted in three 1D coordination polymers; {[Ag(L)NO3]·CH2Cl2}n (2, NO3-form), {[Ag(L)(CH3CN)]PF6}n (3, PF6-form), and {[Ag(L)ClO4]·CH2Cl2}n (4, ClO4-form). Both products 2 (NO3-form) and 3 (PF6-form) show a similar Ag2L2 metallacycle-based ribbon structure with a C-configuration of L except for the anion coordination (NO3−) in 2 and the solvent (CH3CN) coordination in 3. Product 4 (ClO4-form) displays a deformed ladder structure; two parallel (Ag-L)n chains with an out-of-phase of the S-configuration of L as rails, and the crosslinking Ag–S bonds as rungs. Anion exchange studies revealed that the PF6− in 3 was replaced by NO3− to yield product 2 but the reverse process was not possible. Compared to the free ligand L with a medium photoluminescence (PL) intensity, the silver(I) products showed enhanced emissions while the copper(II) complex was silent. [ABSTRACT FROM AUTHOR]

Metallaaromatics are an important class of aromatic compounds, showing diverse and interesting aromatic properties. Radical rhenabenzofurans 1–3 with a fused metallacyclopropene unit are reported, containing d1 Re centers. Computational studies show that the three-membered rhenacyclopropene ring is σ-aromatic, while the rhenafuran ring is nonaromatic. These complexes represent the first radical metallacyclopropenes. α-Metallabenzofuran complexes 4–5 with d0 Re centers and 6 with a d2 Re center are also synthesized. α-Metallabenzofurans 1–6 have adjacent oxidation states (Re(III), Re(IV), and Re(V)). Both the structure and aromatic nature of these metallacycles are affected by the change of oxidation states of the metal center. [ABSTRACT FROM AUTHOR]

The precise activation of C–H bonds will eventually provide chemists with transformative methods to access complex molecular architectures. Current approaches to selective C–H activation relying on directing groups are effective for the generation of five-membered, six-membered and even larger ring metallacycles but show narrow applicability to generate three- and four-membered rings bearing high ring strain. Furthermore, the identification of distinct small intermediates remains unsolved. Here, we developed a strategy to control the size of strained metallacycles in the rhodium-catalysed C−H activation of aza-arenes and applied this discovery to tunably incorporate the alkynes into their azine and benzene skeletons. By merging the rhodium catalyst with a bipyridine-type ligand, a three-membered metallacycle was obtained in the catalytic cycle, while utilizing an NHC ligand favours the generation of the four-membered metallacycle. The generality of this method was demonstrated with a range of aza-arenes, such as quinoline, benzo[f]quinolone, phenanthridine, 4,7-phenanthroline, 1,7-phenanthroline and acridine. Mechanistic studies revealed the origin of the ligand-controlled regiodivergence in the strained metallacycles. The ability to selectively functionalize different sites on simple starting materials is a constant pursuit in organic chemistry. Here, the authors report a catalytic system to regioselectively differentiate and alkynylate different positions on azaarenes via rhodium catalysis. [ABSTRACT FROM AUTHOR]

Exploration of organometallic metallacycles has led to the development of various polycyclic compounds with fascinating structures, which could be used as functional materials. In this work, a new rhenanaphthalene isomer was isolated from the reaction of ReH5(PMe2Ph)3 with o‐ethynylphenyl alkyne in the presence of excess HCl. Its structure was then identified using the single‐crystal X‐ray diffraction and NMR spectroscopy. DFT studies suggest that its formation involves two protonation reactions and two migration reactions. This new rhenanaphthalene isomer enriches the family of metallacycles. [ABSTRACT FROM AUTHOR]

In this joint theoretical and experimental study, an analysis of weak interligand noncovalent interactions within Co(IV) [Cp*Co(phpy)X]+ cobaltacycles (phpy = 2-phenylenepyridine, κ C , N ) was carried out by using the independent gradient model/intrinsic bond strength index (IGM/IBSI) method to evaluate the dependency of the catalytically desired reductive elimination pathway (RE) on the nature of the X ligand. It is shown that the barrier for activation of the RE pathway correlates directly with the IBSI of the X-to-carbanionic chelate's carbon. This correlation suggests that in silico prediction of which X ligand is more prone to operate an efficient Cp*Co-catalyzed directed X-functionalization of an aromatic C–H bond is attainable. A set of experiments involving various sources of X ligands supported the theoretical conclusions. [ABSTRACT FROM AUTHOR]

Binuclear diaminocarbene complexes, which form as a regioisomer mixture in the reaction between isocyanide–palladium(II) complex cis-[PdCl2(CNXyl)2] and 1,3-thiazol-2-amine, are able to exchange an anionic chloride ligand with other halides, such as Br or I. This process also affords binuclear complexes as mixtures of kinetically and thermodynamically controlled regioisomers. In CDCl3 solutions, we observed interconversion of kinetically and thermodynamically controlled regioisomers. The results of the DFT calculations revealed that in CHCl3 solution, each pair of the isomers exhibited two different types of chalcogen bonding such as S···X or S···N; the presence of CBs for two complexes in the solid state was also proven through X-ray crystallographic study. Based on the combined experimental and theoretical data, it could be concluded that thermodynamic favorability for the formation of thermodynamically controlled regioisomers increases in the Cl < Br ≈ I row and correlate well with the energy difference between S···N and S···X (X = Cl, Br, I) chalcogen bonds in kinetically and thermodynamically controlled products. This means that it is possible to change the structure of metallocycles in binuclear diaminocarbene complexes by simply replacing one halide ligand with another. [ABSTRACT FROM AUTHOR]

A series of dinuclear metallacycles of Mn(II), Co(II), Ni(II), Cu(II) and Cd(II) with 1,8-naphthalene dicarboxylic acid (H2NDC) with co-ligand such as 2,2′-bipyridine (bpy) or solvent molecules have been synthesized in a refluxed condition. One mononuclear Ni(II) complex has also been synthesized following the same synthetic procedure with NDC, bpy and pyridine. Among them two polymorphic structures have been isolated. The single crystal X-ray structures of all the metallacycles have been described along with Hirshfield surface analysis. [ABSTRACT FROM AUTHOR]