CCC-NHC Au(iii) pincer complexes as a reliable platform for isolating elusive species.

The reactivity of unprecedented CCC-NHC Au(iii) pincer complexes has been investigated, employing a novel methodology for their preparation. Notably, this marks the inaugural case of CCC-NHC Au(iii) pincer complexes with a central aryl moiety where the two arms of the pincer ligand consist of N-heterocyclic carbenes (NHC). The stability conferred by the CCC-NHC ligand facilitated the isolation of elusive Au(iii) species, encompassing Au(iii)-formate, Au(iii)-F, Au(iii)-Me, and Au(iii)-alkynyl.

Correction: Supramolecular nanocapsules as two-fold stabilizers of outer-cavity sub-nanometric Ru NPs and inner-cavity ultra-small Ru clusters.

Correction for 'Supramolecular nanocapsules as two-fold stabilizers of outer-cavity sub-nanometric Ru NPs and inner-cavity ultra-small Ru clusters' by Ernest Ubasart , , 2022, , 607-615, https://doi.org/10.1039/D1NH00677K.

Light-Induced Reactivity Switch at O-Activating Bioinspired Copper(I) Complexes.

Using light to unveil unexplored reactivities of earth-abundant metal-oxygen intermediates is a formidable challenge, given the already remarkable oxidation ability of these species in the ground state. However, the light-induced reactivity of Cu-O intermediates still remains unexplored, due to the photoejection of O under irradiation. Herein, we describe a photoinduced reactivity switch of bioinspired O-activating Cu complexes, based on the archetypal tris(2-pyridyl-methyl)amine () ligand.

Consolidation of the Oxidant-Free Au(I)/Au(III) Catalysis Enabled by the Hemilabile Ligand Strategy.

In this minireview we survey the challenges and strategies in gold redox catalysis. Gold's reluctance to oxidative addition reactions due to its high redox potential limits its applicability. Initial attempts to overcome this problem focused on the use of sacrificial external oxidants in stoichiometric amounts to bring Au(I) compounds to Au(III) reactive species.

Regioswitchable Bingel Bis-Functionalization of Fullerene C via Supramolecular Masks.

Isomer-pure functionalized fullerenes are required to boost the development of fullerene chemistry in any field, but their multiple functionalization renders a mixture of regioisomers that are very difficult to purify by chromatography. For the specific case of C, its nonspherical geometry makes its regioselective functionalization more challenging than that of spherical C. In this work, the supramolecular mask approach is applied for the first time to C, which is encapsulated in two different nanocapsules to achieve the Bingel bis-cyclopropanation at α-bonds of opposite poles.

Luminescent Chiral Furanol-PAHs via Straightforward Ni-Catalysed C -F Functionalization: Mechanistic Insights into the Scholl Reaction.

Here we report the stepwise synthesis of new nanographenes (NGs) and polycyclic aromatic hydrocarbons (PAHs) obtained via Scholl ring fusion applied at aromatic homologation compounds, which are obtained through one-step Ni-catalysed C -F functionalization. The latter are rapidly accessed valid precursors for the Scholl reaction, and screening of experimental conditions allowed us to describe for the first time furanol-bearing PAHs. Mechanistic insights are obtained by DFT to rationalize the formation of the furanol PAHs under moderately acidic conditions.

Synthesis of C /[10]CPP-Catenanes by Regioselective, Nanocapsule-Templated Bingel Bis-Addition.

The addition of two unsymmetric malonate esters to the Buckminster fullerene C can lead to 22 spectroscopically distinguishable isomeric products and therefore represents a formidable synthesis challenge. In this work, we achieve 87 % selectivity for the formation of a single (in,out-trans-3) isomer by combining three approaches: (i) we use a starting material, in which the two malonates are covalently connected (tether approach); (ii) we form the strong supramolecular complex of C with the shape-persistent [10]CPP macrocycle (template approach) and (iii) we embed this complex further within a self-assembled nanocapsule (shadow mask approach). Variation of the spacer chain shed light on the limitations of the approach and the ring dynamics in the unusual [2]catenanes were studied in silico with atomistic resolution.

Novel NHC-Based Au(I) Complexes as Precursors of Highly Pure Au(0) Nuggets under Oxidative Conditions.

The Lewis-acidic character and robustness of NHC-Au(I) complexes enable them to catalyze a large number of reactions, and they are enthroned as the catalysts of choice for many transformations among polyunsaturated substrates. More recently, Au(I)/Au(III) catalysis has been explored either by utilizing external oxidants or by seeking oxidative addition processes with catalysts featuring pendant coordinating groups. Herein, we describe the synthesis and characterization of N-heterocyclic carbene (NHC)-based Au(I) complexes, with and without pendant coordinating groups, and their reactivity in the presence of different oxidants.

Carboxylic Acid Directed γ-Lactonization of Unactivated Primary C-H Bonds Catalyzed by Mn Complexes: Application to Stereoselective Natural Product Diversification.

Reactions that enable selective functionalization of strong aliphatic C-H bonds open new synthetic paths to rapidly increase molecular complexity and expand chemical space. Particularly valuable are reactions where site-selectivity can be directed toward a specific C-H bond by catalyst control. Herein we describe the catalytic site- and stereoselective γ-lactonization of unactivated primary C-H bonds in carboxylic acid substrates.

Hemilabile MIC^N ligands allow oxidant-free Au(i)/Au(iii) arylation-lactonization of γ-alkenoic acids.

Oxidant-free Au-catalyzed reactions are emerging as a new synthetic tool for innovative organic transformations. Oxidant-free Au-catalyzed reactions are emerging as a new synthetic tool for innovative organic transformations. Still, a deeper mechanistic understanding is needed for a rational design of these processes.

C-H Amination Reactions Mediated by Metastable Pseudo- Masked Aryl-Co-nitrene Species.

Cobalt-catalyzed C-H amination via M-nitrenoid species is spiking the interest of the research community. Understanding this process at a molecular level is a challenging task, and here we report a well-defined macrocyclic system featuring a pseudo- aryl-Co species that reacts with aliphatic azides to effect intramolecular C-N bond formation. Strikingly, a putative aryl-Co═NR nitrenoid intermediate species is formed and is rapidly trapped by a carboxylate ligand to form a carboxylate masked-nitrene, which functions as a shortcut to stabilize and guide the reaction to productive intramolecular C-N bond formation.

Supramolecular nanocapsules as two-fold stabilizers of outer-cavity sub-nanometric Ru NPs and inner-cavity ultra-small Ru clusters.

The synthesis of metallic nanoparticles (MNP) with high surface area and controlled shape is of paramount importance to increase their catalytic performance. The detailed growing process of NP is mostly unknown and understanding the specific steps would pave the way for a rational synthesis of the desired MNP. Here we take advantage of the stabilization properties exerted by the tetragonal prismatic supramolecular nanocapsule 8·(BArF) to develop a synthetic methodology for sub-nanometric RuNP (0.

Nickel-Catalyzed C -OMe Functionalization for Chemoselective Aromatic Homologation En Route to Nanographenes.

A Ni-catalyzed C -OMe ortho-functionalization methodology to form chemoselectively alkyne monoannulation or aromatic homologation products is reported as a novel protocol towards the valorisation of substrates containing C -OMe units. Double activation of C -OMe and C -F bonds is also demonstrated. Further use of aromatic homologation products towards the synthesis of nanographene-like compounds is described.

Well-Defined Aryl-Fe Complexes in Cross-Coupling and C-H Activation Processes.

Herein we explore the intrinsic organometallic reactivity of iron embedded in a tetradentate NC macrocyclic ligand scaffold that allows the stabilization of aryl-Fe species, which are key intermediates in Fe-catalyzed cross-coupling and C-H functionalization processes. This study covers C-H activation reactions using and FeCl, biaryl C-C coupling product formation through reaction with Grignard reagents, and cross-coupling reactions using or in combination with Fe(CO). Synthesis under light irradiation and moderate heating (50 °C) affords the aryl-Fe complexes [Fe(Br)( )(CO)] ( ) and [Fe( )(CO)]Br ( ).

A three-shell supramolecular complex enables the symmetry-mismatched chemo- and regioselective bis-functionalization of C.

Molecular Russian dolls (matryoshkas) have proven useful for testing the limits of preparative supramolecular chemistry but applications of these architectures to problems in other fields are elusive. Here we report a three-shell, matryoshka-like complex-in which C sits inside a cycloparaphenylene nanohoop, which in turn is encapsulated inside a self-assembled nanocapsule-that can be used to address a long-standing challenge in fullerene chemistry, namely the selective formation of a particular fullerene bis-adduct. Spectroscopic evidence indicates that the ternary complex is sufficiently stable in solution for the two outer shells to affect the addition chemistry of the fullerene guest.

Bis-Phenoxo-Cu Complexes: Formal Aromatic Hydroxylation via Aryl-Cu Intermediate Species.

Ullmann-type copper-mediated arylC-O bond formation has attracted the attention of the catalysis and organometallic communities, although the mechanism of these copper-catalyzed coupling reactions remains a subject of debate. We have designed well-defined triazamacrocyclic-based aryl-Cu complexes as an ideal platform to study the C-heteroatom reductive elimination step with all kinds of nucleophiles, and in this work we focus our efforts on the straightforward synthesis of phenols by using HO as nucleophile. Seven well-defined aryl-Cu complexes featuring different ring size and different electronic properties have been reacted with water in basic conditions to produce final bis-phenoxo-Cu complexes, all of which are characterized by XRD.

C-F Activation for C(sp)-C(sp) Cross-Coupling by a Secondary Phosphine Oxide (SPO)-Nickel Complex.

A secondary phosphine oxide (SPO)-nickel catalyst allowed the activation of otherwise inert C-F bonds of unactivated arenes in terms of challenging couplings with primary and secondary alkyl Grignard reagents. The C-F activation is characterized by mild reaction conditions and high levels of branched selectivity. Electron-rich and electron-deficient arenes were suitable electrophiles for this transformation.

Unravelling the mechanism of cobalt-catalysed remote C-H nitration of 8-aminoquinolinamides and expansion of substrate scope towards 1-naphthylpicolinamide.

Previously, an unexpected Co-catalysed remote C-H nitration of 8-aminoquinolinamide compounds was developed. This report provided a novel reactivity for Co which was assumed to proceed through the mechanistic pathway already known for analogous Cu-catalysed remote couplings of the same substrates. In order to shed light into this intriguing, and previously unobserved reactivity for Co, a thorough computational study has now been performed, which has allowed for a full understanding of the operative mechanism.

Aerobic C-C and C-O bond formation reactions mediated by high-valent nickel species.

Nickel complexes have been widely employed as catalysts in C-C and C-heteroatom bond formation reactions. While Ni(0), Ni(i), and Ni(ii) intermediates are most relevant in these transformations, recently Ni(iii) and Ni(iv) species have also been proposed to play a role in catalysis. Reported herein is the synthesis, detailed characterization, and reactivity of a series of Ni(ii) and Ni(iii) metallacycle complexes stabilized by tetradentate pyridinophane ligands with various N-substituents.

Enantioselective C-H Lactonization of Unactivated Methylenes Directed by Carboxylic Acids.

The formidable challenges of controlling site-selectivity, enantioselectivity, and product chemoselectivity make asymmetric C-H oxidation a generally unsolved problem for nonenzymatic systems. Discrimination between the two enantiotopic C-H bonds of an unactivated methylenic group is particularly demanding and so far unprecedented, given the similarity between their environments and the facile overoxidation of the initially formed hydroxylation product. Here we show that a Mn-catalyzed C-H oxidation directed by carboxylic acids can overcome these challenges to yield γ-lactones in high enantiomeric excess (up to 99%) using hydrogen peroxide as oxidant and a Brønsted acid additive under mild conditions and short reaction times.

Highly selective encapsulation and purification of U-based C-EMFs within a supramolecular nanocapsule.

The ability of the tetragonal prismatic nanocapsule 1·(BArF) to selectively encapsulate U-based C EMFs from a soot mixture is reported, showing enhanced affinity for C-based EMFs over C-based EMFs. Molecular recognition driven by the electrostatic interactions between the host and guest is at the basis of the high selectivity observed for ellipsoidal C-based EMFs compared to spherical C-based EMFs. In addition, DFT analysis points towards an enhanced breathing adaptability of nanocapsule 1·(BArF) to C-based EMFs to further explain the selectivity observed when the host is used in the solid phase.

Highly Strained, Radially π-Conjugated Porphyrinylene Nanohoops.

Small π-conjugated nanohoops are difficult to prepare, but offer an excellent platform for studying the interplay between strain and optoelectronic properties, and, increasingly, these shape-persistent macrocycles find uses in host-guest chemistry and self-assembly. We report the synthesis of a new family of radially π-conjugated porphyrinylene/phenylene nanohoops. The strain energy in the smallest nanohoop is approximately 54 kcal mol, which results in a narrowed HOMO-LUMO gap and a red shift in the visible part of the absorption spectrum.

Effective Tetradentate Compound Complexes against spp. that Act on Critical Enzymatic Pathways of These Parasites.

The spectrum and efficacy of available antileishmanial drugs is limited. In the present work we evaluated in vitro the antiproliferative activity of 11 compounds based on tetradentate polyamines compounds against three species (, and ) and the possible mechanism of action. We identified six compounds (, , , , and ) effective against all three spp both on extracellular and intracellular forms.

Size-selective encapsulation of C and C-derivatives within an adaptable naphthalene-based tetragonal prismatic supramolecular nanocapsule.

A novel naphthalene-based 5·(BArF)8 capsule allows for the size-selective inclusion of C60 from fullerene mixtures. Its size selectivity towards C60 has been rationalized by its dynamic adaptability in solution that has been investigated by molecular dynamics. Additionally, 5·(BArF)8 encapsulates C60-derivatives such as C60-PCBM and N-methylpyrrolidine-C60.