Global Minimum Search and Bonding Analysis of Tl2 Hx and Tl3 Hy (x=0-6; y=0-5) Series

A remarkable distinction between boron and carbon hydrides lies in their extremely different bonding patterns and chemical reactivity, resulting in diverse areas of application. Particularly, carbon, characterized by classical two-center - two-electron bonds, gives rise to organic chemistry. In contrast, boron forms numerous exotic and non-intuitive compounds collectively called non-classical structures. It is reasonable to anticipate that other elements of Group 13 exhibit their own unusual bonding patterns; however, our knowledge of the hydride chemistry for other elements in Group 13 is much more limited, especially for the heaviest stable element, thallium. In this work, we performed a conformational analysis of Tl2 Hx and Tl3 Hy (x=0-6, y=0-5) series via Coalescence Kick global minimum search algorithm, DFT, and ab initio quantum chemistry methods; we investigated the bonding pattern using the AdNDP algorithm, thermodynamic stability, and stability toward electron detachment. All found global minimum structures are classified as non-classical structures featuring at least one multi-center bond.

Bismuth Infrared Star: Being at a Glance

Bismuth polycations have garnered significant attention from researchers due to their extraordinary and counter-intuitive structures and stoichiometries. Despite extensive experimental and theoretical investigations, understanding of the bonding in such clusters remains insufficient. An AdNDP bonding analysis was conducted to elucidate the bonding characteristics using both homoatomic and heteroatomic bismuth clusters with various stoichiometries. Analysis of the calculated nucleus-independent chemical shift data confirmed the aromatic nature of these species. Universal bonding patterns were identified that can be applied to a range of homoatomic and heteroatomic bismuth clusters. Additionally, calculations of absorbance and fluorescence spectra were performed to gain insights into the near-infrared emission and establish a potential correlation between absorbance and the identified bonding patterns.

Analysis of the Ability of C6H5I to Phosphoresce

The heavy atom effect is a widely utilized strategy to enhance the phosphorescence intensity of organic molecules. Among the preferred choices, heavy halogen atoms such as bromine (Br) or iodine (I) have gained popularity. However, the incorporation of these heavy atoms can introduce challenges due to the presence of unstable excited states that undergo dissociation upon excitation. This study focuses on investigating the excited states of the C₆H₅I molecule, with particular emphasis on the intricate interplay of spin-orbital coupling effects, employing multireference ab initio methodologies. The absence of phosphorescence in the C₆H₅I molecule is attributed to the efficient energy transfer to dissociative excited states and the near-zero spin-orbital coupling between stable triplet sub-levels and the ground singlet state. To gain insights into the explicit dynamics of the excited states, the research employed Ehrenfest dynamics driven by real-time time-dependent density functional theory (TDDFT). Furthermore, the study explored the complete active space compositions and various post-CASSCF (complete active space self-consistent field) approaches.

On the existence of CO32- microsolvated clusters: a theoretical study

Microsolvated clusters of multiply charged anions play a crucial role in atmospheric chemistry and some of them were previously registered experimentally. At the same time, there are no experimental observations of [CO₃·(H₂O)_n]^2-. The reasons for this may be related to the thermodynamical or kinetical instability of microsolvated CO₃^2- toward autoionization or autoprotonation processes. In this study we theoretically investigate the potential stability of the [CO₃·(H₂O)_n]^2- microsolvated clusters from both perspectives - thermodynamic and kinetic - and we claim they are stable toward autoionization and kinetically semi-stable toward autoprotonation. In addition, the behaviour of CO₃^2- anions in bulk water solvent was analysed to highlight important precautions for synthetic purposes.

Overlapping electron density and the global delocalization of π-aromatic fragments as the reason of conductivity of the biphenylene network

Recently fabricated 2D biphenylene network is an astonishing solid-state material, which possesses unique metal-like conductive properties. At the same time, two-dimensional boron nitride network (2D-BN)-an isoelectronic and structural analogue of biphenylene network, is an insulator with a wide direct bandgap. This study investigates the relationship between the electronic properties and chemical bonding patterns for these species. It is shown that the insulating 2D-BN network possesses a strong localization of electron density on the nitrogen atoms. In turn, for a carbon-containing sheet, we found a highly delocalized electron density and an appreciable overlap of p_z orbitals of neighboring C₆ rings, which might be a reason for the conductive properties of the material.

Superalkali Coated Rydberg Molecules

A series of complexes of Na, K, NH₄, and H₃O with [bpy.bpy.bpy]cryptand, [2.2.2]cryptand, and spherical cryptand were investigated via DFT and ab initio methods. We found that by coating Rydberg molecules with the “organic skin” one could further decrease their ionization potential energy, reaching the values of ∼1.5 eV and a new low record of 1.3 eV. The neutral cryptand complexes in this sense possess a weakly bounded electron and may be considered as very strong reducing agents. Moreover, the presence of an organic cage increases the thermodynamic stability of Rydberg molecules making them stable toward the proton detachment.