Comprehensive determination of highly symmetric transition metal dichalcogenide multilayers.

This study expands the JAM notation to systematically explore stacking configurations of transition metal dichalcogenide (TMDC) multilayers, covering both conventional and Janus structures. We extended JAM to represent four TMDC types: 1H, 1T, Janus 1H, and Janus 1T, adding characters to describe these structures. Additionally, we updated the JAM algorithm to generate stacking configurations and produce VASP-compatible POSCAR files.

H©CuH: a covalently bonded planar pentacoordinate hydrogen star.

A hydrocopper H©CuH star with planar pentacoordinate hydrogen (ppH) was designed. This structure is the global minimum, exhibiting dynamic stability. Its planar geometry is supported by five peripheral Cu-H-Cu 3c-2e σ-bonds and a central 6c-2e σ-bond.

CHO Isomers: Insights into Potential Interstellar Species.

2-Methoxyethanol, with a formula CHO was recently identified in the massive protocluster NGC 6334I. However, its structural isomers, 1,2-propanediol and 1,3-propanediol, remain undetected despite extensive searches in the Sgr B2 region. In this study, we explored the potential energy surface of the CHO system using CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVTZ calculations, identifying 11 species, with the geminal diols 2,2-propanediol and 1,1-propanediol as the most stable forms.

Enhancing : Accurate Rate Constants with Canonical Variational Transition State Theory and the Hindered Rotor Model.

The recrossing effect and hindered rotations can lead to significant inaccuracies in rate constant calculations using transition state theory and the harmonic oscillator approximation. To address these issues, we enhanced , a -based computational tool, by integrating the canonical variational transition state theory (CVT) and the hindered rotor model, effectively mitigating the limitations of traditional methods. CVT rate constants are calculated using electronic structure data from nonstationary points along the minimum-energy path.

Dicyclopenta[4,3,2,1-cde:4',3',2',1'-pqr]-peri-tetracene: Synthesis and an Example of Annulene-within-an-Annulene Aromaticity in Different Redox States.

We report a robust strategy for tuning the electronic structure and chemical stability of π-conjugated polycyclic hydrocarbons (PHs). By fusing two cyclopentadienyl rings in the peri-tetracene bay regions, we introduce antiaromatic character into the π-system, leading to unique photophysical and electronic properties. A stable mesityl-substituted dicyclopenta-peri-tetracene derivative was synthesized through stepwise formylation/intramolecular cyclization at the bay regions of the dihydro peri-tetracene precursor, followed by oxidative dehydrogenation.

Planar Pentacoordinate Halogens.

Planar hypercoordinate motifs represent an intriguing frontier in chemistry, challenging traditional bonding norms. As electronegativity of the central atom increases, achieving planar hypercoordination becomes more difficult due to restricted delocalization, making the design of planar hypercoordinate halogens particularly puzzling. Here, we conduct an extensive computational survey of LiX (n=4, 5, 6; X=F, Cl, Br, I) clusters, revealing a starlike D-symmetry global minimum in LiX (X=F, Cl, Br) with a planar pentacoordinate halogen (ppX), where X is located at the center of LiX crown.

Mechanism of Dinitrogen Photoactivation by PPFe Complexes: Thermodynamic and Kinetic Computational Studies.

The PPFe(N)(H) catalyst showed a significant ammonia yield under light irradiation. However, under thermal conditions, the hydrogen evolution reaction (HER) is favored over the nitrogen reduction reaction (NRR), making PPFe(N)(H) an ideal system for studying the competition between both reactions. In this study, we used a series of computational tools to elucidate the photochemical reaction mechanism for the NRR and thermal pathways leading to the HER with this catalyst.

Planar Tetracoordinate Silicon in SiCu Cluster.

Photoelectron spectroscopy and theoretical calculations have identified the global minimum structure of the 16-valence electron SiCu cluster, which features a planar tetracoordinate silicon (ptSi) in a rhombic arrangement. The Si and Cu triangles are interconnected by a Si/Cu edge, forming an ordered chain-like structure. Besides the conventional 2c-2e σ-bond connecting Si and Cu, the stability of this cluster is reinforced by a delocalized 3c-2e σ-bond in Cu and a π-bond in Si.

Exploring aromatic rings with planar tetracoordinate group 13-15 atoms.

This study examines systems containing planar tetracoordinate group 13-15 atoms (E) within pentagonal CHE rings bridged by Si or Ge atoms. A detailed chemical bonding analysis of eleven candidates shows that true tetracoordination is achieved only in the CHNGe system.

Core-electron contributions to the magnetic response of molecules with heavy elements and their significance in aromaticity assessments.

This study delves into the magnetic response of core electrons and their influence on the global magnetic response of planar and three-dimensional systems containing heavy elements, employing the removing valence electron (RVE) approximation. We also explore electronic aromaticity indices to understand the potential role of core electrons on electron delocalization in the absence of an external perturbation. The study reveals that core electrons significantly contribute to the overall magnetic response, especially to the magnetic shielding, affecting the interpretation of aromaticity.

In Quest of the Missing CHO Isomers in the Interstellar Medium: A Theoretical Search.

Ethylene glycol (CHO), the only diol detected in the interstellar medium (ISM), is a key component in the synthesis of prebiotic sugars. Its structural isomer, methoxymethanol, has also been found in the ISM. Our results show that neither ethylene glycol (ethane-1,2-diol) nor methoxymethanol is the most stable isomer.

Exploring the Use of "Honorary Transition Metals" To Push the Boundaries of Planar Hypercoordinate Alkaline-Earth Metals.

The quest for planar hypercoordinate atoms (phA) beyond six has predominantly focused on transition metals, with dodecacoordination being the highest reported thus far. Extending this bonding scenario to main-group elements, which typically lack d orbitals despite their larger atomic radius, has posed significant challenges. Intrigued by the potentiality of covalent bonding formation using the d orbitals of the heavier alkaline-earth metals (Ae = Ca, Sr, Ba), the so-called "honorary transition metals", we aim to push the boundaries of planar hypercoordination.

An Efficient Growth Pattern Algorithm (GrowPAL) for Cluster Structure Prediction.

Identifying the lowest energy isomers in large clusters is a major challenge. Here, we introduce the Growth Pattern Algorithm (GrowPAL), a new approach that generates initial seeds composed of atoms from the system with atoms through an interstitial-type addition (I-type) mechanism. We evaluated the effectiveness of GrowPAL on Lennard-Jones (LJ) clusters with up to = 80 atoms, verifying the algorithm's ability to find challenging minima such as LJ and the partially icosahedral LJ with fewer optimizations than existing methods.

Reversible Capture Mechanism of CO as a Zn(II)-Methylcarbonate.

In this study, we elucidate the reaction mechanism for capturing CO with the ZnL(MeOH) complex (L=diacetyl-2-(4-methyl-3-thiosemicarbazone)-3-(2-hydrazinatopyridine)) in a methanol solution, using density functional theory calculations. One pathway involves the protonation of ZnL(MeOH) by methylcarbonic acid, followed by ligand exchange of MeOH with MeOCO . An alternative mechanism suggests a tautomerization between ZnL(MeOH) and Zn(HL)(OMe), followed by CO insertion.

Breaking the plane: BH is a three-dimensional structure.

In this study, we delved into the structure of BH and questioned some of its accepted assumptions. By exploring the potential energy surface, we found a new three-dimensional structure as the global minimum. This finding is in contrast with the previously hypothesized planar and cage-like models.

Understanding Aromaticity in [5]Helicene-Bridged Cyclophanes: A Comprehensive Study.

This study explores the aromaticity of doubly [5]helicene-bridged (1,4)cyclophane and triply [5]helicene-bridged (1,3,5)cyclophane via calculations of the magnetic response and of electronic aromaticity indices. The primary objective is to assess the π-electron delocalization to determine whether they sustain global ring currents associated with π aromaticity. The molecules show local ring currents in the presence of an external magnetic field.

Li E Li : Tetrel Sandwich Complexes with 10-π-Electrons.

When (4n +2) π-electrons are located in single planar ring, it conventionally qualifies as aromatic. According Hückel's rule, systems possessing ten π-electrons should be aromatic. Herein we report a series of D  Li E Li sandwich structures, representing the first global minima featuring ten π-electrons E ring (E=Si-Pb).

Unveiling the electronic and structural consequences of removing two electrons from BH.

The notion that a regular icosahedron is unattainable in neutral BH has persisted for nearly 70 years. This is because 24 valence electrons are used for B-H bonds, while another 24 electrons are necessary to maintain the deltahedron, unlike the 26 used in the dianion. According to Wade-Mingos rules, the neutral system should be a deltahedron with a capped face.

Distribution and morphological variation of tree ferns (Cyatheaceae) along an elevation gradient.

Knowing how species and communities respond to environmental change is fundamental in the context of climate change. The search for patterns of abundance and phenotypic variation along altitudinal gradients can provide evidence on adaptive limits. We evaluated the species abundance and the variation in morphometric and stomatal characters in five tree ferns species (Cyathea fulva, C.

Seeking the most stable isomer of azahomocubanes.

This study examines the stability and protonation properties of four potential azahomocubanes. Through high-level computations, we find that 9-azahomocubane is the most stable isomer, closely followed by 5-azahomocubane, 1-azahomocubane, and 2-azahomocubane. However, understanding the stability of the systems with a nitrogen atom incorporated into a highly constrained polycyclic environment extends beyond mere bond angles or hybridization considerations.

Planar pentacoordinate s-block metals.

The presence of a delocalized π-bond is often considered an essential criterion for achieving planar hypercoordination. Herein, we show that σ-delocalization could be sufficient to make the planar configuration the most stable isomer in a series of planar pentacoordinate s-block metals. High-level computations reveal that the global minimum of a series of interalkali and interalkali-alkaline earth clusters (LiNa, LiMg, NaMg, KCa, CaRb, RbSr, and SrCs) adopts a singlet structure with a planar pentacoordinate lithium or alkaline earth metal (AE = Mg, Ca, Sr).

Correction: Structure and bonding of molecular stirrers with formula BM and BM (M = Zn, Cd, Hg).

Correction for 'Structure and bonding of molecular stirrers with formula BM and BM (M = Zn, Cd, Hg)' by Rui Yu , , 2020, , 12312-12320, https://doi.org/10.1039/D0CP01603A.