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This study delves into the intriguing realm of chalcogen-bonding interactions, specifically focusing on tellurium(II) and/or tellurium(IV) interactions with iodide species within six crystals. Utilising comprehensive computational chemistry calculations and underpinned by crystallographic data retrieved from the Cambridge Structural Database, this research elucidates the supramolecular aggregation, bonding nature and interaction energetics of Te...I non-covalent bonds in a series of crystals containing each of tellurium(II), tellurium(IV) and iodide. The investigation encompasses a variety of molecular assemblies, ranging from zero-dimensional to complex three-dimensional architectures. Tellurium(II) atoms formed Te...I interactions in six of the crystals but tellurium(IV) participated in Te...I interactions in only three crystals despite there being equal numbers of tellurium(II) and tellurium(IV) atoms in the zero- and onedimensional assemblies. Several computational tools, including Molecular Electrostatic Potential (MEP) surfaces, Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) analyses, provide a nuanced understanding of the electron density topology and charge transfer mechanisms. In some assemblies, where the Te...I interactions are ~3.2 Å, the interaction energies are very large, i.e. 25.6 to 38.8 kcal mol-1, suggesting partial covalent character, an observation corroborated by the NBO analysis; longer Te...I separations correlate with reduced energies, i.e. 3.1 to 7.0 kcal mol-1. Crucially, it is noteworthy that the Te...I interactions identified in this study are distinctly characterised as chalcogen bonds, rather than halogen bonds. [ABSTRACT FROM AUTHOR]

As(III) S‐adenosylmethionine methyltransferases, pivotal enzymes in arsenic metabolism, facilitate the methylation of arsenic up to three times. This process predominantly yields trivalent mono‐ and dimethylarsenite, with trimethylarsine forming in smaller amounts. While this enzyme acts as a detoxifier in microbial systems by altering As(III), in humans, it paradoxically generates more toxic and potentially carcinogenic methylated arsenic species. The strong affinity of As(III) for cysteine residues, forming As(III)‐thiolate bonds, is exploited in medical treatments, notably in arsenic trioxide (Trisenox®), an FDA‐approved drug for leukemia. The effectiveness of this drug is partly due to its interaction with cysteine residues, leading to the breakdown of key oncogenic fusion proteins. In this study, we extend the understanding of As(III)′s binding mechanisms, showing that, in addition to As(III)−S covalent bonds, noncovalent O⋅⋅⋅As pnictogen bonding plays a vital role. This interaction significantly contributes to the structural stability of the As(III) complexes. Our crystallographic analysis using the PDB database of As(III) S‐adenosylmethionine methyltransferases, augmented by comprehensive theoretical studies including molecular electrostatic potential (MEP), quantum theory of atoms in molecules (QTAIM), and natural bond orbital (NBO) analysis, emphasizes the critical role of pnictogen bonding in these systems. We also undertake a detailed evaluation of the energy characteristics of these pnictogen bonds using various theoretical models. To our knowledge, this is the first time pnictogen bonds in As(III) derivatives have been reported in biological systems, marking a significant advancement in our understanding of arsenic's molecular interactions. [ABSTRACT FROM AUTHOR]

Combining computations and X-ray structure analysis we have demonstrated that [Pt(CN4)]2− can behave as a Lewis acid inside an enzyme's cavity. The nature of a counterintuitive contact found between a catalytically active GLN residue belonging to a mitochondrial synthase and the Pt(II) center was investigated by combining molecular dynamics and quantum mechanics calculations. Results confirm the electron acceptor role of [Pt(CN4)]2−, serving as an inspiration for the design of biomolecular cages able to tweak the nucleophilic/electrophilic character of an organometallic compound. [ABSTRACT FROM AUTHOR]

The Cambridge Structural Database was surveyed for crystals featuring Hg⋯S secondary-bonding interactions for mercury(II) compounds (excluding organomercury compounds). In all, 43 examples of crystals including intermolecular Hg⋯S interactions operating largely in isolation from other directional interactions were detected with the Hg⋯S interactions within zero-, one- and two-dimensional aggregation patterns. Over 50% of the aggregates are one-dimensional with topologies ranging from linear, zigzag and helical chains, and ribbons to tapes; 30% of the crystals exhibit zero-dimensional aggregates. Crucially, selected examples were subjected to DFT calculations with mapping of the molecular electrostatic potentials (MEPs) of the molecules as well as quantum theory of atoms in molecules (QTAIM), non-covalent interaction plot (NCIPLOT) and natural bond order (NBO) investigations. This study confirms the presence of σ-/π-holes or positive belts at the mercury atom depending on the coordination geometry, defined by covalently and non-covalently bound donor atoms. In molecules coordinated by sulphur donors, the σ-hole at the sulphur atom merges with the positive belt around the mercury atoms, assisting in the formation of spodium bonds and providing higher directionality. The QTAIM/NCIPLOT analysis supports both the existence and non-covalent nature of the spodium bonds. Finally, the NBO analysis reveals charge transfer effects indicating the existence of LP → σ* orbital interactions in the studied molecules; LP is a lone-pair. The energy of stabilisation provided by spodium bonds ranges from a low 3 kcal mol−1 to a high 19 kcal mol−1, i.e. values often greater than those by conventional hydrogen-bonding interactions. [ABSTRACT FROM AUTHOR]

Unraveling the binding preferences involved in the formation of a supramolecular complex is key to properly understand molecular recognition and aggregation phenomena, which are of pivotal importance to biology. The halogenation of nucleic acids has been routinely carried out for decades to assist in their X-ray diffraction analysis. The incorporation of a halogen atom on a DNA/RNA base not only affected its electronic distribution, but also expanded the noncovalent interactions toolbox beyond the classical hydrogen bond (HB) by incorporating the halogen bond (HalB). In this regard, an inspection of the Protein Data Bank (PDB) revealed 187 structures involving halogenated nucleic acids (either unbound or bound to a protein) where at least 1 base pair (BP) exhibited halogenation. Herein, we were interested in disclosing the strength and binding preferences of halogenated A···U and G···C BPs, which are predominant in halogenated nucleic acids. To achieve that, computations at the RI-MP2/def2-TZVP level of theory together with state of the art theoretical modeling tools (including the computation of molecular electrostatic potential (MEP) surfaces, the quantum theory of "Atoms in Molecules" (QTAIM) and the non-covalent interactions plot (NCIplot) analyses) allowed for the characterization of the HB and HalB complexes studied herein. [ABSTRACT FROM AUTHOR]

In this manuscript substituent effects in several silicon tetrel bonding (TtB) complexes were investigated at the RI-MP2/def2-TZVP level of theory. Particularly, we have analysed how the interaction energy is influenced by the electronic nature of the substituent in both donor and acceptor moieties. To achieve that, several tetrafluorophenyl silane derivatives have been substituted at the meta and para positions by several electron donating and electron withdrawing groups (EDG and EWG, respectively), such as –NH2, –OCH3, –CH3, –H, –CF3 and –CN substituents. As electron donor molecules, we have used a series of hydrogen cyanide derivatives using the same EDGs and EWGs. We have obtained the Hammett's plots for different combinations of donors and acceptors and in all cases we have obtained good regression plots (interaction energies vs. Hammet's σ parameter). In addition, we have used the electrostatic potential (ESP) surface analysis as well as the Bader's theory of atoms in molecules (AIM) and noncovalent interaction plot (NCI plot) techniques to further characterize the TtBs studied herein. Finally, a Cambridge Structural Database (CSD) inspection was carried out, retrieving several structures where halogenated aromatic silanes participate in tetrel bonding interactions, being an additional stabilization force of their supramolecular architectures. [ABSTRACT FROM AUTHOR]

A hyperresponsive tool to assess supramolecular catalysis, the cyclization of di‐epoxides into cyclic ethers is used to elucidate the difference between pnictogen‐bonding and Lewis acid catalysis systematically. For all stereoisomers, most tested catalysts follow the Baldwin rules. Brønsted acid and anion–π catalysis afford almost only Baldwin products. Lewis acids such as SbCl3, BF3 and BiCl3 give the poorest selectivity, with at least 50 % Baldwin (B) products for all stereoisomers. In clear contrast, optimized pnictogen‐bonding catalysts operating on the Sb(III) and the Sb(V) level give the fused anti‐Baldwin (A) bicycles as the main product of trans epoxides, independent of syn or anti relation of the two epoxides. In the cis series, Sb(III) pnictogen‐bonding catalysts afford BA products almost exclusively for syn diastereomers, while anti diastereomers give equal amounts of BA and AB products. Sb(V) pnictogen‐bonding catalysts show similarly special trends. These unique characteristics support that pnictogen‐bonding catalysis differs from Lewis acid catalysis and can arguably be defined as its non‐covalent counterpart, just like hydrogen‐bonding catalysis is understood and appreciated as the non‐covalent counterpart of Brønsted acid catalysis. Computational studies on the origin of anti‐Baldwin selectivity reveal Sb(V) catalysts with an introvert deep σ hole surrounded by an almost planar ring of ligands. Central pnictogen‐bond attraction against peripheral steric repulsion then forces the epoxide to break open. In contrast, transient antimony oxidation in cyclic intermediates accounts for the chemoselectivity of Sb(III) catalysts. Presumably due to insufficient accessibility of their σ holes, the activity of tetrel‐bonding catalysts is negligible. The division between powerful pnictogen‐bonding and irrelevant tetrel‐bonding catalysts does not exist with the respective orthodox Lewis acids and thus supports that σ‐hole and Lewis acid catalysis are not the same. [ABSTRACT FROM AUTHOR]

The term matere bond has been recently used to refer to an attractive noncovalent interaction between any element of group 7 acting as an electrophile and any atom (or group of atoms) acting as a nucleophile. The utilization of metals such as σ-hole donors is starting to attract the attention of the scientific community. In this manuscript, a comparison between matere bonds and well-known σ-hole interactions (halogen and chalcogen bonds) is carried out using three X-ray structures, retrieved from the Cambridge structural database (CSD), and density functional theory calculations (DFT). The novelty of this work resides in the utilization of a neutral Re(VII) system as the matere bond donor and multivalent chalcogen and halogen donors. In fact, as far as our knowledge extends, the description of σ-hole interactions in Se(VI) is unprecedented in the literature. The σ-hole interactions in Re(VII), Se(VI) and Cl(VII) electron acceptors are analyzed and compared using several computational tools. [ABSTRACT FROM AUTHOR]

In this study we propose to coin the term Wolfium bond (WfB) to refer to a net attractive force (noncovalent interaction) between any element of group 6 and electron donor atoms (neutral molecules or anions) and to differentiate it from a coordination bond (metal‐ligand interaction). We provide evidence of the existence of this interaction by inspecting the X‐ray crystal structure of proteins containing Molybdopterin and Tungstopterin cofactors from the Protein Data Bank (PDB). The plausible biological role of the interaction as well as its physical nature (antibonding Wf‐Ligand orbital involved) are also analyzed by means of ab initio calculations (RI‐MP2/def2‐TZVP level of theory), Atoms in Molecules (AIM), Natural Bond Orbital (NBO) and Noncovalent Interactions plot (NCIplot) analyses. [ABSTRACT FROM AUTHOR]

We report high-level ab initio calculations (CCSD(T)(full)/CBS//SCS-RI-MP2(full)/aug-cc-pwCVTZ) that demonstrate the importance of cooperativity effects when Anion–π and CH/π interactions are simultaneously established with benzene as the π-system. In fact, most of the complexes exhibit high cooperativity energies that range from 17% to 25.3% of the total interaction energy, which is indicative of the strong influence of the CH/π on the Anion–π interaction and vice versa. Moreover, the symmetry-adapted perturbation theory (SAPT) partition scheme was used to study the different energy contributions to the interaction energies and to investigate the physical nature of the interplay between both interactions. Furthermore, the Atoms in Molecules (AIM) theory and the Non-Covalent Interaction (NCI) approach were used to analyze the two interactions further. Finally, a few examples from the Protein Data Bank (PDB) are shown. All results stress that the concurrent formation of both interactions may play an important role in biological systems due to the ubiquity of CH bonds, phenyl rings, and anions in biomolecules. [ABSTRACT FROM AUTHOR]

Osme bonds have been recently defined as the attractive interaction between an element of group 8 acting as an electrophile and any atom or group of atoms acting as a nucleophile. To date, the known examples of osme bonds in X-ray structures involve mostly the highly reactive OsO4 and amines and amine oxides. In this work, evidence supporting the existence of osme bonds in osmium(VI) derivatives is reported. In particular, nitrido-osmium(VI) complexes that present square-pyramidal geometries are well disposed to participate in osme bonds opposite to the Os≡N bond. By using a combination of experimental and theoretical results, the existence and importance of this new class of σ-hole interactions is demonstrated in the solid state of several nitrido-osmium(VI) derivatives. [ABSTRACT FROM AUTHOR]

This feature article highlights the discovery and development of phosphanoxyl complex chemistry starting from (neutral) low-coordinate phosphorus radicals and the quest of metal ligation effects. We describe synthesis and reactions of precursors, namely 2,2,6,6-tetramethylpiperidinoxyl (TEMPO) substituted phosphane tungsten(0) complexes. Trapping reactions of transient phosphanoxyl complexes, formed via thermal homolytic N–O bond cleavage, as well as their use in radical polymerisations are illustrated, thus revealing an interesting reactivity dichotomy. DFT calculations provide insight into thermal stabilities of precursors and the resulting spin density distributions (SDDs) in these reactive intermediates. Systematic studies on the dependance of the electron delocalisation in phosphanoxyl complexes have been performed examining different substitution pattern at phosphorus and different co-ligand combinations at the tungsten(0) center. Preliminary results on Mn and Fe complexes are reported. [ABSTRACT FROM AUTHOR]

In this study the ability of metal coordinated Chalcogen (Ch) atoms to undergo Chalcogen bonding (ChB) interactions has been evaluated at the PBE0-D3/def2-TZVP level of theory. An initial CSD (Cambridge Structural Database) inspection revealed the presence of square planar Pd/Pt coordination complexes where divalent Ch atoms (Se/Te) were used as ligands. Interestingly, the coordination to the metal center enhanced the σ-hole donor ability of the Ch atom, which participates in ChBs with neighboring units present in the X-ray crystal structure, therefore dictating the solid state architecture. The X-ray analyses were complemented with a computational study (PBE0-D3/def2-TZVP level of theory), which shed light into the strength and directionality of the ChBs studied herein. Owing to the new possibilities that metal coordination offers to enhance or modulate the σ-hole donor ability of Chs, we believe that the findings presented herein are of remarkable importance for supramolecular chemists as well as for those scientists working in the field of solid state chemistry. [ABSTRACT FROM AUTHOR]

Introduction: Electrogram (EGM) fractionation is often associated with diseased atrial tissue; however, mechanisms for fractionation occurring above an established threshold of 0.5 mV have never been characterized. We sought to investigate during sinus rhythm (SR) the mechanisms underlying bipolar EGM fractionation with high‐density mapping in patients with atrial fibrillation (AF). Methods: Forty‐five patients undergoing AF ablation (73% paroxysmal, 27% persistent) were mapped at high density (18562 ± 2551 points) during SR (Rhythmia). Only bipolar EGMs with voltages above 0.5 mV were considered for analysis. When fractionation (> 40 ms and >4 deflections) was detected, we classified the mechanisms as slow conduction, wave‐front collision, or a pivot point. The relationship between EGM duration and amplitude, and tissue anisotropy and slow conduction, was then studied using a computational model. Results: Of the 45 left atria analyzed, 133 sites of EGM fragmentation were identified with voltages above 0.5 mV. The most frequent mechanism (64%) was slow conduction (velocity 0.45 m/s ± 0.2) with mean EGM voltage of 1.1 ± 0.5 mV and duration of 54.9 ± 9.4 ms. Wavefront collision was the second most frequent (19%), characterized by higher voltage (1.6 ± 0.9 mV) and shorter duration (51.3 ± 11.3 ms). Pivot points (9%) were associated with the highest degree of fractionation with 70.7 ± 6.6 ms and 1.8 ± 1 mV. In 10 sites (8%) fractionation was unexplained. The EGM duration was significantly different among the 3 mechanisms (p =.0351). Conclusion: In patients with a history of AF, EGM fractionation can occur at amplitudes > 0.5 mV when in SR in areas often considered not to be diseased tissue. The main mechanism of EGM fractionation is slow conduction, followed by wavefront collision and pivot sites. [ABSTRACT FROM AUTHOR]

In this work we report structural and computational studies of favipiravir, which is now used as a drug for COVID-19 treatment. The molecule is completely flat and stabilized by an intramolecular O–H···O hydrogen bond, yielding a six-membered pseudo-aromatic ring. The aromaticity index of this pseudo-aromatic ring was found to be 0.748, while the same indix for the pyrazine ring in favipiravir was found to be 0.954. The crystal packing of favipiravir is mainly constructed through intermolecular N–H···O, N–H···N and C–H···O hydrogen bonds, yielding a 3D supramolecular framework with a zst topology defined by the point symbol of (65·8). The crystal structure of favipiravir is further stabilized by weak C–F···F–C intermolecular type II dihalogen interactions, yielding a 1D supramolecular polymeric chain. More than 80% of the total Hirshfeld surface area for favipiravir is occupied by H···H/C/N/O/F and C···N/O contacts. Energy frameworks have been calculated to additionally analyze the overall crystal packing. It was established that the structure of favipiravir is mainly characterized by the dispersion energy framework followed by the less significant electrostatic energy framework contribution. Finally, by using density functional theory (DFT) calculations and the quantum theory of atoms in molecules, we have assigned the interaction energy of each hydrogen bond, which can be helpful to develop scoring functions to be used in force fields/docking calculations. [ABSTRACT FROM AUTHOR]

The important role of spodium bonding (SpB) in Zn(II) and Cd(II) complexes is highlighted in this feature article. SpB has been recommended to distinguish coordination bonds (high covalent character) from non-covalent contacts. Here, two new d10-metal dithiophosphate complexes, [M(L)2]2 {where M = Zn (1) and Cd (2); L = O,O′-bis(4-tert-butylphenyl) phosphorodithioate} have been synthesized in purely aqueous media and characterized by elemental and spectral analyses. The X-ray crystallography analyses indicate that both complexes are dinuclear, in which each metal atom is coordinated with four sulfur atoms in a distorted tetrahedral environment containing two four-membered chelate rings joined to a central eight-membered ring through metal (Zn/Cd) atoms. In complex 1 the eight-membered ring possesses a "saddle" conformation located on a two-fold axis of symmetry, C2, while in complex 2 it possesses a centrosymmetric "twisted chair" conformation, Ci. In addition, the oxygen and sulfur atoms belonging to the bridging ligands form intramolecular SpBs with Zn(II) in 1 and Cd(II) in 2. The existence of intramolecular SpBs in both complexes is evidenced by DFT calculations by using the Bader's Quantum Theory of Atoms-in-Molecules (QTAIM) combined with the non-covalent interaction plot (NCI plot) index that is based on the reduced density gradient (NCI-RDG) method. A Hirshfeld surface study has been carried out to understand the intermolecular contacts in the crystal lattice. [ABSTRACT FROM AUTHOR]

Premature ventricular complexes (PVCs) are increasingly recognized, as the use of ECG wearables becomes more widespread. In particular, PVCs arising from both the right ventricular outflow tract (RVOT) and left ventricular outflow tract (LVOT) comprise the majority of these arrhythmias and form a significant component of an electrophysiology practice. A keen understanding of the correlative anatomy of the outflow tracts, in addition to recognizing key ECG indices illustrating PVC sites of origin, are fundamental in preparing for a successful ablation. Patient selection, incorporating symptomatology, structural disease, and PVC burden can pose a challenge, though tools such as the ABC‐VT risk score may help identify those patients with a higher risk of clinical deterioration. Utilizing intracardiac echocardiography to highlight salient anatomic features not visible with fluoroscopy allows for a more precise and safer ablation. Interpretation of intracardiac EGMs, and the careful examination for low amplitude highly fractionated pre‐potentials, enhanced by the advent of new developed mapping/ablation catheters, remains crucial. Utilizing these tools will guide the electrophysiologist to an efficient and effective outflow tract PVC ablation. [ABSTRACT FROM AUTHOR]

Herein we report experimental evidence for the shortest intermolecular distance reported for two electronically-different hydrogen atoms in the solid state. The Hδ+⋯Hδ− non-covalent interaction was studied using theoretical calculations indicating that electrostatic and dispersion forces are of paramount importance. [ABSTRACT FROM AUTHOR]

Iodonium complexes incorporating tertiary amines have been synthesised to study and explore why such species comprised of alkyl amines are relatively rare. The complexes were characterised in solution (1H and 15N NMR spectroscopy) and the solid state (SCXRD), and analysed computationally. [ABSTRACT FROM AUTHOR]

The generality of nucleophilic iodonium interactions (NIIs) has been demonstrated by preparing a range of silver(I) and iodonium (I+) complexes and studying their 15N NMR chemical shifts, with the first example of a NII-complex involving a 2-coordinate silver(I) complex being confirmed by X-ray crystallography, and its nucleophilicity studied by DFT calculations. [ABSTRACT FROM AUTHOR]

The synthesis and X-ray characterization of a new dinuclear Zn complex using a tetradentate N2O2 donor Schiff base and azide as an anionic co-ligand of formula [(DMSO)2ZnL(μ1,1-N3)Zn(N3)2] (1) are reported herein. This complex forms self-assembled dimers in the solid state governed by σ-hole tetrel bonding interactions (C⋯N) involving the Zn-coordinated methoxy group. The σ-hole tetrel bonding interaction has been differentiated from a trifurcated CH3⋯N H-bonding interaction using the NBO analysis and the inspection of the donor–acceptor orbital interactions. Other interactions (like π-stacking) are also important governing the solid state architecture of the dinuclear Zn-complex. The energy of π-stacking interaction has also been estimated using DFT calculations and several computational tools (MEP surfaces, QTAIM and NCI plot analyses). [ABSTRACT FROM AUTHOR]

In this study, Fe3O4 nanoparticles (FeNPs) decorated with halogenated perylene diimides (PDIs) have been used for capturing VOCs (volatile organic compounds) through noncovalent binding. Concretely, we have used tetrachlorinated/brominated PDIs as well as a nonhalogenated PDI as a reference system. On the other hand, methanol, ethanol, propanol, and butanol were used as VOCs. Experimental studies along with theoretical calculations (the BP86-D3/def2-TZVPP level of theory) pointed to two possible and likely competitive binding modes (lone pair–π through the π-acidic surface of the PDI and a halogen bond via the σ-holes at the Cl/Br atoms). More in detail, thermal desorption (TD) experiments showed an increase in the VOC retention capacity upon increasing the length of the alkyl chain, suggesting a preference for the interaction with the PDI aromatic surface. In addition, the tetrachlorinated derivative showed larger VOC retention times compared to the tetrabrominated analog. These results were complemented by several state-of-the-art computational tools, such as the electrostatic surface potential analysis, the Quantum Theory of Atoms in Molecules (QTAIM), as well as the noncovalent interaction plot (NCIplot) visual index, which were helpful to rationalize the role of each interaction in the VOC···PDI recognition phenomena. [ABSTRACT FROM AUTHOR]

It is often said that pnictogen‐bonding catalysis, and σ‐hole catalysis in general, would not work in aqueous systems because the solvent would interfere as an overcompetitive pnictogen‐bond acceptor. In this study, we show that the transfer of pnictogen‐bonding catalysis from hydrophobic solvents to aqueous systems is possible by replacing only hydrophobic with hydrophilic substrates, without changing catalyst or reaction. This differs from conventional covalent Lewis acid catalysts, which are instantaneously destroyed by ligand exchange. With their water‐proof substituents in place of exchangeable ligands, pnictogen‐bonding catalysts, the supramolecular counterpart of Lewis acid catalysts, are evinced to catalyze transfer hydrogenation of quinolines in neutral aqueous systems. To secure these results, we introduce a water‐soluble fluorogenic substrate that releases a coumarin upon the reduction of quinolines instead of activated quinolidiniums, and stiborane catalysts with deepened σ holes. They demonstrate that pnictogen‐bonding catalysts can operate in higher‐order architectures for supramolecular systems catalysis under biologically relevant conditions, and provide an operational assay for high‐throughput catalyst screening by fluorescence imaging, in situ under relevant aqueous conditions. [ABSTRACT FROM AUTHOR]

The synthesis and X-ray characterization of two new dinuclear Zn complexes using a tridentate N2O donor reduced Schiff base and acetate or azide as the anionic coligands with the formula [Zn2L2(OAc)2] (1) and [Zn2L2(N3)2] (2) is described. The presence of acidic NH groups in the complexes, owing to the utilization of a reduced Schiff-based ligand and also strong H-bond acceptors (electron rich atoms from the anionic coligands), facilitates the formation of infinite 1D assemblies governed by H-bonding interactions in the solid state. These assemblies have been analysed energetically using density functional theory (DFT) calculations and several computational tools (symmetry adapted perturbation theory (SAPT), molecular electrostatic potential (MEP) surfaces, quantum theory of atoms in molecules (QTAIM) and non-covalent interaction index (NCI) plot analyses). [ABSTRACT FROM AUTHOR]

Two mononuclear iron(III) complexes, [FeL1Cl]·CH3CN (1) and [FeL2(N3)] (2) {H2L1 = N,N′-bis(5-chlorosalicylidene)diethylenetriamine and H2L2 = N,N′-bis(5-bromosalicylidene)diethylenetriamine}, have been synthesized and characterized by X-ray crystallographic studies. In the solid state, there are strong hydrogen bonding interactions in both complexes due to the presence of the Fe(III)-coordinated amino group and anionic ligands, which are strong hydrogen bond donors and acceptors, respectively. These interactions have been studied by means of DFT and QTAIM calculations. Moreover, in the complex 2, the formation of halogen bonding interactions (Br⋯π) has been analyzed. The MEP analysis evidences the existence of a σ-hole at the bromine atom, and the concomitant Br⋯π interaction has been confirmed by QTAIM analysis. [ABSTRACT FROM AUTHOR]

A heteronuclear cobalt(III)/potassium complex, [(L1)2Co2K(L2)2]I3 {where H2L1 = N,N-bis(3-ethoxysalicylidene)2,2-dimethyl-1,3-propanediamine and HL2 = 3-ethoxysalicylaldehyde}, has been synthesized and characterized by several analytical techniques including single crystal X-ray diffraction analysis. The I3− anions form discrete dimers in the solid state with an I⋯I distance of 3.55 Å. The molecular electrostatic potential (MEP) surface shows a depletion of the charge density at the extension of I–I covalent bond (σ-hole). Although this value is negative due to the overall negative charge of the system, the value is significantly smaller (in absolute value) than the value at the negative belt around the I atoms, indicating that the binding mode observed in the X-ray structure minimizes the electrostatic repulsion. The I3−⋯I3− dimer in the gas phase is not stable. However, it is energetically favourable in water and acetonitrile, thus suggesting the possibility that an anti-electrostatic halogen⋯halogen interaction may exist in solution. This gives a plausible explanation for the formation of these counterintuitive dimers in the solid state, where the effect of the surrounding molecules is expected to be higher than water solvation. Agreeably, the NCI plot computational tool also suggests that the interaction is attractive in nature. [ABSTRACT FROM AUTHOR]

This manuscript combines a search in the Cambridge Structural Database (CSD) and theoretical density functional theory (DFT) calculations to analyse the existence and importance of charge assisted pnictogen and halogen bonds involving halophosphonium cations. Trivalent pnictogen atoms typically have three σ-holes and are able to establish up to three pnictogen bonds (PnBs). In phosphonium salts, the phosphorus atom forms four covalent bonds and, consequently, four σ-holes are located at the extension of these bonds. Therefore, up to four charge assisted PnBs can be formed between these holes and the counterions or any electron rich atom. The covalent bond arrangement around the phosphorus atom is similar to that around tetravalent tetrel atoms and converts into a similar pattern of σ-hole interactions. We have found and described this type of charge assisted pnictogen bond in various halophosphonium crystal structures. Moreover, the competition of charge assisted PnBs with charge assisted halogen bonds (HaBs) has been also studied both theoretically and by analysing the CSD. [ABSTRACT FROM AUTHOR]

Three tetranuclear zinc dicyanamide complexes with three potential hexadentate reduced Schiff base ligands have been synthesized and characterized. In the solid state structure of complex 1, the aromatic ring of one complex is located in the U-cavity formed by two aromatic rings and the (Zn2)L2 (dicyanamide)2 macrocycle of the adjacent complex establishing π⋯π and C–H⋯π interactions. In sharp contrast, the presence of two methyl groups in addition to the longer methylene chain in 2 and 3 provokes a totally different packing, where the methyl groups are located in the U-cavity instead of the aromatic ring, establishing several C–H⋯π contacts. Thus, the presence of a methyl spacer and an additional methyl substituent in the alkyl chain of 2 and 3 is crucial since it has an enormous effect on the crystal packing. The DFT study is devoted to the analysis of the competition between C–H⋯π and π⋯π interactions observed in the solid state of complexes 1 and 2 and also to the characterization of the interactions using the NCI (non-covalent interaction) plot index computational tool. The molecular electrostatic potential (MEP) surface of complex 2 as a model of complexes 1–3 has also been calculated. [ABSTRACT FROM AUTHOR]

The nature and characteristics of the C–H⋯π interactions that play an important role in crystal packing of two iron(III) complexes have been discussed. [Fe(HL1)2(NCSe)2]Cl (1) and [Fe(HL2)2]Cl (2), where HL1 = 2-((3-(methylamino)propylimino)methyl)-6-ethoxyphenol and H2L2 = 2-[[[2-[(2-hydroxyethyl)amino]ethyl]imino]methyl]-6-methoxyphenol, have been synthesized and characterized by single crystal X-ray diffraction, IR, UV-visible spectroscopy and elemental analyses. Their structures have been confirmed by a single crystal X-ray diffraction study. The crystal packing of 1 shows an infinite 1D supramolecular network of C–H⋯π interactions involving either the π-cloud of the aromatic ring or the π-system of the SeCN ligand with several C–H bonds (both aliphatic and aromatic). Formation of a 2D supramolecular sheet in the solid state structure of 2 is facilitated by the C–H⋯π and π⋯π interactions. The DFT calculations have been conducted to determine the interaction energies in these complexes. The molecular electrostatic potential (MEP) surface analysis implies that the values are large and negative at the SeCN ligand (in 1) and over the aromatic ring (both in 1 and 2). Thus, both π-systems are well suited for interacting with positive MEP regions at the aliphatic and aromatic H-atoms. Moreover, the interactions have also been characterized using the non-covalent interaction (NCI) plot index computational tool. [ABSTRACT FROM AUTHOR]

In the setting of catheter ablation of ventricular tachycardia (VT), invasive programmed ventricular stimulation (PVS) is considered an important tool to assess the (residual) inducibility of ventricular arrhythmias and determine the acute success of the procedure. In patients with cardiovascular implantable electronic devices, noninvasive programmed stimulation via implantable cardioverter‐defibrillator (ICD) leads can be an alternative to the invasive PVS with intracardiac catheters. The advantages of noninvasive programmed stimulation include preprocedure planning of the electrophysiology procedure to ensure optimal conditions for successful catheter ablation of VT. Following the procedure, noninvasive programmed stimulation has been shown to be used as a guide for repeat early ablation, to offer better programming of ICD, to offer prognostic value regarding the VT recurrence, and to guide antiarrhythmic drug therapy. The noninvasive nature of noninvasive programmed stimulation makes it an attractive alternative to PVS in patients with ICD who have not undergone catheter ablation of VT to obtain prognostic value regarding the occurrence of VT. [ABSTRACT FROM AUTHOR]

Efficient approaches towards the synthesis of various N-substituted 1,3,5-triazinanes based on a transformation of N -alkyl-1,5,3-dioxazepanes or on a domino reaction involving condensation of various amines, amides, and paraformaldehyde are described for the first time. Mg(ClO4)2 was shown to be one of the most potent additives for the condensation. The proposed approaches permit the synthesis of a broad spectrum of substituted sym -triazinanes in good yields with relatively easy workup. In the case of the multicomponent reaction, the approach allows the preparation of the target substances from simple and easily accessible reagents. The representatives of the resulting compounds were found to possess no antimicrobial or cytotoxic activity in in vitro bioassays. [ABSTRACT FROM AUTHOR]

Background: Morphology algorithms are currently recommended as a standalone discriminator in single‐chamber implantable cardioverter defibrillators (ICDs). However, these proprietary algorithms differ in both design and nominal programming. Objective: To compare three different algorithms with nominal versus advanced programming in their ability to discriminate between ventricular (VT) and supraventricular tachycardia (SVT). Methods: In nine European centers, VT and SVTs were collected from Abbott, Boston Scientific, and Medtronic dual‐ and triple‐chamber ICDs via their respective remote monitoring portals. Percentage morphology matches were recorded for selected episodes which were classified as VT or SVT by means of atrioventricular comparison. The sensitivity and related specificity of each manufacturer discriminator was determined at various values of template match percentage from receiving operating characteristics (ROC) curve analysis. Results: A total of 534 episodes were retained for the analysis. In ROC analyses, Abbott Far Field MD (area under the curve [AUC]: 0.91; P <.001) and Boston Scientific RhythmID (AUC: 0.95; P <.001) show higher AUC than Medtronic Wavelet (AUC: 0.81; P <.001) when tested for their ability to discriminate VT from SVT. At nominal % match threshold all devices provided high sensitivity in VT identification, (91%, 100%, and 90%, respectively, for Abbott, Boston Scientific, and Medtronic) but contrasted specificities in SVT discrimination (85%, 41%, and 62%, respectively). Abbott and Medtronic's nominal thresholds were similar to the optimal thresholds. Optimization of the % match threshold improved the Boston Scientific specificity to 79% without compromising the sensitivity. Conclusion: Proprietary morphology discriminators show important differences in their ability to discriminate SVT. How much this impact the overall discrimination process remains to be investigated. [ABSTRACT FROM AUTHOR]

Careful mapping, early detection of AV conduction damage and cryothermal energy availability are essential in dealing with ablation procedures at the parahisian region. [ABSTRACT FROM AUTHOR]

A hetero-dinuclear nickel(II)/lead(II) complex with a compartmental 'reduced Schiff base' ligand (having inner N2O2 and outer O2O2′ compartments) has been prepared and characterized by elemental and spectral analysis. Single crystal X-ray diffraction analysis confirms its structure. Nickel(II) is placed in the inner N2O2 compartment and lead(II) is placed in the outer O2O2′ compartment of the compartmental reduced Schiff base. The complex forms a tetranuclear supramolecule via non-covalent Pb⋯Cl tetrel bonding interactions. The DFT study is devoted to analyze these tetrel bonding interactions that involve the σ-hole at the hemicoordinated Pb(II) atom. The tetrel bonding interactions have been characterized using Bader's theory of atoms in molecules (AIM). [ABSTRACT FROM AUTHOR]

Studying noncanonical intermolecular interactions between a ligand and a protein constitutes an emerging research field. Identifying synthetically accessible molecular fragments that can engage in intermolecular interactions is a key objective in this area. Here, it is shown that so‐called "π‐hole interactions" are present between the nitro moiety in nitro aromatic ligands and lone pairs within protein structures (water and protein carbonyls and sulfurs). Ample structural evidence was found in a PDB analysis and computations reveal interaction energies of about −5 kcal mol−1 for ligand–protein π‐hole interactions. Several examples are highlighted for which a π‐hole interaction is implicated in the superior binding affinity or inhibition of a nitro aromatic ligand versus a similar non‐nitro analogue. The discovery that π‐hole interactions with nitro aromatics are significant within protein structures parallels the finding that halogen bonds are biologically relevant. This has implications for the interpretation of ligand–protein complexation phenomena, for example, involving the more than 50 approved drugs that contain a nitro aromatic moiety. [ABSTRACT FROM AUTHOR]

A thorough evaluation of the CSD and DFT computations were conducted to assess if intramolecular π–hole interactions can stabilize a conformer of nitro aromatics. It was found that this can only be the case when the nitro N-atom and an interacting electron-rich atom are separated by at least four bonds. Data from the solid state correspond well to the gas phase calculations and stabilizing energies were estimated to be as large as about 2–3 kcal mol−1, which is in the order of weak hydrogen bonding interactions. [ABSTRACT FROM AUTHOR]

In this manuscript, we combine a search in the Cambridge Structural Database (CSD) and ab initio calculations (RI-MP2/def2-TZVP level of theory) to analyse the ability of Sn to establish ‘like–like’ tetrel bonding interactions. The CSD inspection revealed that noncovalent Sn…Sn contacts are common in X-ray structures and that two predominant structural patterns exist. Moreover, the nature of like–like tetrel bonding interactions was investigated in a total of 81 dimers by wave function and ab initio (MP2)-based methods. In these dimers the σ-hole donor molecules are para-substituted-phenylstannane derivatives (SnH3Ar, where Ar = p-YC6H4) and the electron rich molecules are para-substituted-2,6-dimethylstannabenzenyl anions [2,6-dimethyl-4-X-C5H4Sn(−)], where X,Y = Me2N, H2N, tBu, H, F, CF3, CN, P(CN)2 and SO2CN. The binding energies calculated at the RI-MP2 level of theory yield an energy scale of 2–13 kcal mol−1 which is comparable to that of hydrogen bonds and demonstrates that Sn…Sn interactions can be considered relevant for determining supramolecular assemblies in the solid state and constitute an underexplored inorganic structural motif that can be used in crystal engineering. The utilization of different substituents allows us to study their influence upon the interaction energies. We have obtained Hammett's plots for the two combinations (X = H and Y variable or Y = H and X = variable) and in both cases we have obtained good regression plots (interaction energies vs. Hammett's σ parameter). Finally, we have used Bader's theory of “atoms-in-molecules” to show that the electron density computed at the bond critical point that connects both Sn atoms correlates with the strength of this noncovalent interaction. [ABSTRACT FROM AUTHOR]

Two heteronuclear cobalt(iii)/sodium complexes, [(H2O)2Co(H2L1)Na(N3)2] (1) and (μ-N3)2[(N3)Co(H2L2)Na]2 (2) have been synthesized by the reaction of two compartmental reduced Schiff bases, H2L1 [(1,2-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol)] and H2L2 [(2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol)], with cobalt(ii) nitrate hexahydrate in methanol. Structures of both the complexes have been confirmed by single crystal X-ray diffraction analysis. In each complex, cobalt(iii) is located in the inner N2O2 compartment and sodium is placed in the outer O2O′2 compartment of the respective ligands. In complex 1, the saturated five-membered chelate ring assumes a half-chair conformation, thereby facilitating the anti-orientations of two N–H bonds, which in turn favours the formation of very strong hydrogen bonds forming an infinite one-dimensional assembly. Formation of this one-dimensional chain is also supported by C–H…π (arene) interactions. On the other hand, the best hydrogen bond donor NH groups are in syn disposition (as the saturated chelate ring is six-membered and assumes a chair conformation) and do not participate in the crystal packing in complex 2. However, very strong C–H…π(N3) interactions have been established in complex 2, where the π-system of the bridging azide ligand participates as the π-donor. A search in the Cambridge structural database (CSD) has also been carried out to investigate the abundance and directionality of the interaction using different pseudohalides. Energies of all these supramolecular interactions were estimated by DFT calculations including Grimme's dispersion correction and characterized by the NCI plot index computational tool. [ABSTRACT FROM AUTHOR]

In this manuscript we evaluate the X-ray structure of five new pertechnetate derivatives of general formula [M(H2O)4(TcO4)2], M=Mg, Co, Ni, Cu, Zn (compounds 1-5) and one perrhenate compound Zn(H2O)4(ReO4)2 (6). In these complexes the metal center exhibits an octahedral coordination with the pertechnetate units as axial ligands. All compounds exhibit the formation of directional Tc···O Matere bonds (MaBs) that propagate the [M(H2O)4(TcO4)2], into 1D supramolecular polymers in the solid state. Such 1D polymers are linked, generating 2D layers, by combining additional MaBs and hydrogen bonds (HBs). Such concurrent motifs have been analyzed theoretically, suggesting the noncovalent s-hole nature of the MaBs. The interaction energies range from weak (~ - 2 kcal/mol) for the MaBs to strong (~ - 30 kcal/mol) for the MaB+HB assemblies, where HB dominates. In case of M=Zn, the corresponding perrhenate Zn(H2O)4(ReO4)2 complex, has been also synthesized for comparison purposes, resulting in the formation of an isostructural Xray structure, corroborating the structure-directing role of Matere bonds. [ABSTRACT FROM AUTHOR]

The ability of tetrahedral lead(IV) to establish noncovalent σ‐hole tetrel bonding interactions with electron‐rich atoms (ElRs; anions and Lewis bases) has been studied at the PBE0‐D3/def2‐TZVPD level of theory. An analysis of the Cambridge Crystallographic Database (CSD), which is a convenient storehouse of geometric information, has been performed to investigate the existence of tetrel bonding interactions involving tetrahedral lead(IV) derivatives. Several examples of tetrel bonding interactions that are crucial in crystal packing, ranging from 0D to 2D assemblies, have been found. In addition to the energetic and theoretical study of several XPb(CH3)3⋅⋅⋅ElR complexes (X=F, CN, CF3, and CH3), Bader's theory of atoms in molecules has also been used to further analyze and characterize the noncovalent interactions described herein. [ABSTRACT FROM AUTHOR]

In this study, a PDB (Protein Data Bank) analysis and theoretical calculations (PBE0‐D3/def2‐TZVP level of theory) were combined to analyze the impact of S⋅⋅⋅Sn tetrel‐bonding interactions in the activation mechanism of peroxisome proliferator‐activated receptors (PPARs) by two organotin derivatives, triphenyltin (TPT) and tributyltin (TBT). The presence of a covalently bonded CYS285 to the organotin molecule was found to be key to enhance the σ‐hole‐donor ability of the tin atom, thus strengthening the tetrel‐bonding interaction with a sulfur atom belonging to a vicinal methionine residue (MET364). Tetrel bonds in action: A combined Protein Data Bank and computational analysis (PBE0‐D3/def2‐TZVP) revealed the importance of S⋅⋅⋅Sn tetrel‐bonding interactions in the mechanism of activation of peroxisome proliferator‐activated receptors (PPARs) by organotin molecules. [ABSTRACT FROM AUTHOR]

In this research paper we report synthesis of two planar ligands, namely 1,3-dimethyl-5-(4ʹ/3ʹ-pyridylazo)-6-aminouracil: HL1 (1 ) for 4ʹ-pyridyazo- and HL2 ( 2 ) for 3ʹ-pyridyazo-group and, moreover, their nickel (II) square planar complexes ([Ni II (L1) 2 ] ( 3 ) and ([Ni II (L2) 2 ] ( 4 )). The report is also included solid and solution state structure of the compounds and study of noncovalent stacking interactions. Crystal structures of the ligands, 1 and 2 are monoclinic with alike space group P 2 1 / c and the complex 3 is also monoclinic with space group C 2/ c . The molecular electrostatic potential (MEP) analysis shows that the ligands possess both π-basic and π-acid character in the same framework over the center of the pyridine and the pyrimidine rings, respectively, favoring electrostatically enhanced π-π stacking interaction among the molecular units. Upon complexation, π-acidity of the pyrimidine ring increases, and the complex 3 exhibits lone pair (lp)-π stacking interaction involving lone pair of the pyridine N-atom and π-acid pyrimidine plane. The study evidences that the ligands exist in azo-enamine-keto tautomer in solid and hydrazone-imine-keto in solution state and get coordinated with nickel (II) via azo- N and uracil-6- N H , to form a distorted square planar complex. Electronic absorption bands/energies obtained from experimental and theoretical (TDDFT) study are indeed alike, giving reliability to the level of theory and the absorption band assignments. Moreover, the synthesized compounds containing uracil and pyridine fragments exhibit π-π/lp-π interactions with considerable energy for stabilization of their assemblies in the solid state. [ABSTRACT FROM AUTHOR]

Arrhythmogenic cardiomyopathy (ACM) is a heart disease characterized by a fibrotic replacement of myocardial tissue and a consequent predisposition to ventricular arrhythmic events, especially in the young. Post-mortem studies and the subsequent diffusion of cardiac MRI have shown that left ventricular involvement in arrhythmogenic cardiomyopathy is common and often develops early. Regarding the arrhythmic risk stratification, the current scores underestimate the arrhythmic risk of patients with arrhythmogenic cardiomyopathy with left involvement. Indeed, the data on arrhythmic risk stratification in this group of patients are contradictory and not exhaustive, with the consequence of not correctly identifying patients at a high arrhythmic risk who deserve protection from arrhythmic death. We propose a literature review on arrhythmic risk stratification in patients with ACM and left involvement to identify the main features associated with an increased arrhythmic risk in this group of patients. [ABSTRACT FROM AUTHOR]

Homoleptic [L−I−L]+ iodine(I) complexes (where L is a R3R2R1N tertiary amine) were synthesized via the [L−Ag−L]+→ [L−I−L]+ cation exchange reaction. In solution, the amines form [R3R2R1N−Ag−NR1R2R3]+ silver(I) complexes, which crystallize out from solution as the meso‐[L−Ag−L]+complexes, as characterized by X‐ray crystallography. The subsequent [L−I−L]+ iodine(I) analogues were extremely reactive and could not be isolated in the solid state. Density functional theory (DFT) calculations were performed to study the Ag+−N and I+−N interaction energies in silver(I) and iodine(I) complexes, with the former ranging from −80 to −100 kJ mol−1 and latter from −260 to −279 kJ mol−1. The X‐ray crystal structures revealed Ag+⋅⋅⋅Cπ and Ag+⋅⋅⋅H−C short contacts between the silver(I) cation and flexible N‐alkyl/N‐aryl groups, which are the first of their kind in such precursor complexes. [ABSTRACT FROM AUTHOR]

Three homoleptic Hg(S2CNR2)2, for R = ethyl (1), isobutyl (2), and cyclohexyl (3), compounds apparently exhibit a steric-dependent supramolecular association in their crystals. The small group in 1 allows for dimer formation via covalent Hg–S interactions through an eight-membered {–HgSCS}2 ring as the dithiocarbamato ligands bridge centrosymmetrically related Hg atoms; intradimer Hg···S interactions are noted. By contrast, centrosymmetrically related molecules in 2 are aligned to enable intermolecular Hg···S interactions, but the separations greatly exceed the van der Waals radii. The large group in 3 precludes both dimerization and intermolecular Hg···S interactions. Computational chemistry indicates that the potential region at the Hg atom is highly dependent on the coordination geometry about the Hg atom. Intramolecular (1) and intermolecular (2) spodium bonding (SpB) is demonstrated. Even at separations approaching 0.4 Å beyond the sum of the assumed van der Waals radii, the energy of the stabilization afforded by the structure directs SpB in 2 amounts to approximately 2.5 kcal/mol. A natural bond orbital (NBO) analysis points to the importance of the LP(S) → σ*(Hg–S) charge transfer and to the dominance of the dispersion forces and electron correlation to the SpB in 2. [ABSTRACT FROM AUTHOR]

In this study, a series of electron donor (–NH2, –NMe2 and –tBu) and electron-withdrawing substituents (–F, –CN and –NO2) were used to tune the nucleophilicity or electrophilicity of a series of square planar Ni2+, Pd2+ and Pt2+ malonate coordination complexes towards a pentafluoroiodobenzene and a pyridine molecule. In addition, Bader's theory of atoms in molecules (AIM), noncovalent interaction plot (NCIplot), molecular electrostatic potential (MEP) surface and natural bond orbital (NBO) analyses at the PBE0-D3/def2-TZVP level of theory were carried out to characterize and discriminate the role of the metal atom in the noncovalent complexes studied herein. We hope that the results reported herein may serve to expand the current knowledge regarding these metals in the fields of crystal engineering and supramolecular chemistry. [ABSTRACT FROM AUTHOR]

The ability of metal clusters involving elements from group 11 (Ag, Cu, Au) to favorably interact with π systems of different size and electronic nature was evaluated at the PBE0‐D3/def2‐TZVPP//PBE0‐D3/def2‐TZVP level of theory. The M9 clusters (M=Cu, Ag, Au) were used as σ‐hole and σ‐lump donors, and benzene, trifluorobenzene, and hexafluorobenzene as aromatic rings. In addition, the study was expanded to the analysis of extended π systems by using naphthalene and anthracene as well as their corresponding perfluorinated derivatives. Furthermore, Bader's theory of Atoms in Molecules as well as natural bonding orbital and spin‐density calculations were used to further investigate and characterize the regium–π and σ‐lump complexes described herein. Apparently, regium–π bonds have not previously been described in the literature and may be of great importance in the understanding of organocatalytic processes involving aromatic substrates as well as in the design of new materials based on this novel subclass of σ‐hole bonding. [ABSTRACT FROM AUTHOR]

In this manuscript, we combined a search in the Cambridge Structural Database (CSD) and ab initio calculations (RI-MP2/def2-TZVPD level of theory) to analyze the ability of trisulphide and triselenide moieties to establish chalcogen ‘like-like’ interactions. A preliminary CSD inspection revealed two predominant structural patterns, depending on the anti or syn conformation adopted by the substituents of the S3/Se3 bridge, leading to bifurcated or double chalcogen bonding interactions, respectively. In order to analyze these two relevant structural motifs we have used a series of S and Se derivatives Ch3X2 (Ch = S and Se and X = H, F, CN, and CF3) which act as both electron donor (using the lone pairs) and acceptor (using the σ-holes) entities. Besides, we have carried out “atoms in molecules” (AIM) and natural bonding orbital (NBO) analyses to further describe and characterize the chalcogen bonding interactions described herein. As far as we know, chalcogen···chalcogen interactions involving trichalconides (S3/Se3) have not been previously described in literature a may be of great importance in the preparation and characterization of new solids based on this subclass of σ-hole bonding. [ABSTRACT FROM AUTHOR]

The mononuclear CoIII complex [Co(Br3Cat-py)2(py)2]- Cl·8H2O (1, py = pyridine, Br3pyCatH2 = 3,5,6-tribromo-4-pyridiniumcatechol) was synthesized through the reaction of CoCl2·6H2O with tetrabromocatechol in the presence of an excess of pyridine at elevated temperature. The solid-state structure was determined by X-ray crystallography, which disclosed the valence-tautomerism-induced aromatic nucleophilic substitution of the tetrabromocatecholate ligands by pyridine. A cyclic voltammetry study revealed the redox flexibility of both the transition-metal centre and the coordinated redox-active ligand in this complex. Moreover, 1 exhibits moderately strong catalytic activity and mimics the function of phenoxazinone synthase. A detailed kinetic study disclosed that the extra positive charges at the ligand backbone resulting from the substitution of the Br atoms by pyridyl groups could play an anchoring role for the stabilization of the complex-substrate intermediate. This process resembles those in biological systems, in which the extraordinary catalytic activities of metalloenzymes in various biochemical processes are associated with substrate recognition and the stabilization of the reactive intermediates through diverse supramolecular forces. DFT calculations at the M06-2X/6-31+G* level of theory were used to support the mechanistic aspects related to both the redox-driven aromatic nucleophilic substitution and the biomimetic catalysis. [ABSTRACT FROM AUTHOR]

In this study, the ability of beryllium compounds to establish π-hole bonding interactions has been evaluated at the RI-MP2/def2-TZVPD level of theory. A search of the Protein Data Bank revealed some X-ray crystal structures in which BeF3− moieties act as electron-acceptor entities. We have used [Mg(BeF3)(HCOO)] ( 1) as a π-hole bond donor and CO, CH3CN, NH3, O(CH3)2, S(CH3)2, H3PO, and glycine as electron-rich entities. In all cases, favorable binding energies were obtained, reflecting the attractive nature of the interaction involving the trivalent beryllium atom (-BeF3 moiety). In addition, we have used Bader's theory of 'atoms in molecules' and noncovalent interaction (NCI) plot analysis to further investigate and characterize the π-hole complexes described herein. To the best of our knowledge, π-hole interactions involving beryllium have not hitherto been described in the literature. [ABSTRACT FROM AUTHOR]