Topological Unraveling the [3+2] Cycloaddition (32CA) Reaction between N-Methylphenylnitrone and Styrene Catalyzed by Chromium Tricarbonyl Complex from Electron Localization Function and Catastrophe Theory.

We have investigated the reaction mechanisms of [3+2] cycloaddition (32CA) between N-methylphenylnitrone and styrene catalyzed by chromium tricarbonyl complex at the MPWB1K/6-311G(d,p) level of approximation. Activation energy analysis reveals that...

Balanced Infrared Nonlinear Optical Performance Achieved by Modulating Covalency and Ionicity Distributions in Electron Localization Function Map

Nonlinear optical (NLO) efficiency (dij) and laser-induced damage threshold (LIDT) are mainly determined by covalency and ionicity, respectively, the incompatibility between which makes balancing dij and LIDT challenging in an...

Electronic and Magnetic Structures of New Interstitial Boron Sub-Oxides B12O2:X (X = B, C, N, O)

The boron-rich boron sub-oxide rhombohedral B6O considered in B12O2 full formulation has a large O-O spacing of ~3 Å and a central vacant position that can receive interstitial atoms X, forming a central O-X-O alignment in the dodecaboron cage as observed in well-known triatomic B12 compounds as B12{C-C-C}, B12{N-B-N}, etc. Plane wave density functional theory (DFT) based calculations of unrestricted geometry relaxation of B12{O-X-O}, X = B, C, N, and O let one identify new ternary sub-oxides, all found cohesive while showing different d(X-O) distances ranging from d(B-O) = 1.95 Å down to d(O-O) = 1.73 Å with intermediate d(C-O) = 1.88 Å. The different magnitudes were assigned to the chemical affinities of X-inserts versus host oxygen with the increasing development of X-O bonding along the series with larger cohesive B12{O-O-O}. From the atom projected charge density, B presents none, while significant magnitudes are shown on C and N, the latter developing bonding with terminal oxygen atoms especially N. The presence of unpaired valence electrons leaves nonbonding charge density on X = C, N interstitial compounds, which, besides the relative isolation of the central C and N lead to the onset of magnetic moments: M(C) = 1.9 μB, and M(N) = 1 μB in a ferromagnetic ground state. Atom-resolved assessments are provided with the magnetic charge density and electron localization function electron localization function (ELF) projections on one hand and the site and spin projected density of states and the chemical bonding based on the overlap integral Sij within the COOP criterion, on the other hand.

A re-interpretation of the structure of the silver borate, Ag16B4O10, in the light of the extended Zintl–Klemm concept

The borate Ag16B4O10 was synthesized at high temperature and at elevated oxygen pressures [Kovalevskiy et al. (2020). Chem. Sci. 11, 962–969]. Its structure consists of [B4O10]8− polyanions (isostructural to P4O10) embedded in an Ag matrix. According to the standard valences Ag+, B3+ and O2−, the formula has an excess of eight e− which the above authors proposed were located, pairwise, in four Ag4 tetrahedra within the silver substructure. That conclusion was based on the semiconducting and diamagnetic properties, as well as the very small `attractors' of the Electron Localization Function (ELF) found at the centre of these Ag4 tetrahedra. However, a large overlap of the projected density of states (DOS) of silver and oxygen indicated possible dispersion interactions between both atomic species. In this article, an alternative description is proposed based on the extended Zintl–Klemm concept. The anion [B4O10]8− can be formulated as Ψ-[N4O10] P4O10, if it is assumed that the eight e− are transferred to the four B atoms, so converting them into Ψ-N, this then makes sense of its similarity with P4O10, [N4(CH2)6], adamantane and tetraisopropyladamantane. When the Ag atoms connect to the O atoms, they arrange as the H atoms do in hexamethylenetetramine (HMTA). If the two lone pairs of each of the bridging O atoms in Ψ-[N4O10] are equated to the C—H bonds in HMTA, then, this same equivalence exists between the C—H bonds and the O—Ag bonds in the compound Ag16B4O10. The 24 Ag atoms surrounding each [B4O10]8− group prolong the sphalerite structure of the borate anion by means of Ag—O bonds which also fit the sphalerite structure formed of AgO. The eight excess electrons might then be distributed between the Ag and the O atoms, so making sense of the mixing of the Ag and O states. The Ag atoms bonded to the O atoms of the [B4O10]8− groups form a coat that interconnects the borate anions through Ag—O bonds. To establish the validity of this new proposal, the study needs to be extended to the compound Ag3B5O9.

Substituent effects on the structure and properties of (para-C5H4X)Ir(PH3)3 complexes in the ground state (S0) and first singlet excited state (S1): DFT and TD-DFT investigations

The ground and lowest singlet excited state geometries of selected ( para-C5H4X)Ir(PH3)3 iridabenzene complexes ( para-substituent = NH2, OMe, Me, H, F, Cl, CCl3, CF3, NO2) are optimized using the MPW1PW91 procedure employing the LanL2DZ(Ir) and 6-311G(d, p) (C, H, N, O, P, F, Cl, P) basis sets. The excited state is generated using the time-dependent density function method. The effects of electron-donating groups and electron-withdrawing groups on the energy, atomization energy, rotational constants, and frontier orbital energies in the first singlet excited state (S1) of iridabenzene are investigated and compared to those of the ground state (S0). The Ir–C and Ir–P bonds in the studied molecules are analyzed by electron localization function and localized-orbital locator methods. The correlations between the Ir-C and Ir–P bond distances, electron localization function, and localized-orbital locator values Hammett constants (σp) and dual parameters (σI and σR) are given for the two studied states. The para-delocalization index is used for investigation of the aromaticity of the studied complexes.