Energy Decomposition Analysis Research Articles

Metal Influence on Cyaphide-Azide 1,3-Dipolar Cycloaddition Reactions: Aromaticity and Activation Strain.

The factors governing 1,3-dipolar cycloaddition reactions involving C≡P-containing compounds are computationally explored in detail using quantum chemical tools. To this end, the parent process involving tBuN3 and tBuCP is analyzed and compared to the analogous reaction involving organometallic cyaphide complexes (metal=Au, Pt, Ge, Mg), in order to understand the role of the metal fragment in such transformations. It is found that while the metal fragment does not significantly influence the aromaticity of the corresponding concerted transition states or the regioselectivity of the transformation, it may modify the reactivity of the cyaphide complexes (i. e. Ge and Mg cyaphide complexes are comparatively more reactive). The computed reactivity trends and the factors behind the regioselectivity of the cycloaddition reaction are quantitatively analyzed with the help of the activation strain model in combination with the energy decomposition analysis method.

Theoretical study on formation mechanism of acetic acid associating configurations and their distributions under saturated conditions.

The vapor-liquid equilibrium (VLE) properties of acetic acid systems generally behave strong non-ideality due to the associating interaction among acetic acid molecules. Theoretical study of the associating mechanism will provide guidance for the VLE property prediction, which is crucial for the designing on the separation process of the acetic acid systems. In this work, the association conformers and their distribution on acetic acid molecules in saturated gas and liquid phase were firstly studied. The proportions of the acetic acid monomer and multimers were obtained, which will contribute to the foundation for the vapor-liquid equilibrium simulations. The association mechanism on acetic acid molecules was then investigated by comparing among the structures and non-bonded interaction energies of different dimers. The structure of the cyclic dimer containing two OC-HO hydrogen bonds, may be found probably when acetic acid molecules approached. Electronic properties of different acetic acid dimers showed that the electrons around carbonyl oxygen atoms were deflected by the attraction of hydrogen atoms in the other molecule, which polarized the acetic acid molecules when the hydrogen bonds between acetic acid molecules were formed, providing theoretical basis for the polarized acetic acid molecular model. In this work, the molecular dynamics (MD) simulations and DFT calculations were conducted through the software GROMACS and Gaussian 09, respectively. For the MD simulations, the OPLS-AA force field was used as the atomic force field, with the cubic simulation cells constructed by Packmol program. For the DFT calculations, the M06-2X functional was employed for the optimization of the associating structures with the 6-311G** basis sets. Hydrogen bonding energies of dimers were corrected for the basis set superposition error (BSSE) and the deformation energies of monomers. Furthermore, the energy decomposition analysis was conducted at DFT/M06-2X/def-tzp level by the ADF software, and the wave function analysis was conducted by the Multiwfn software including the atom in molecule (AIM) topology analysis, the electronic potential analysis, and the electron density difference analysis.

Mono(Lewis Base)-Stabilized Gallium Iodide: An Unexplored Class of Promising Ligands.

Quantum-chemical (DFT) calculations on hitherto unknown base(carbene)-stabilized gallium monoiodides (LB→GaI) suggest that these systems feature one lone pair of electrons and a formally vacant p-orbital - both centered at the central gallium atom - and exhibit metallomimetic behavior. The calculated reaction free energies as well as bond dissociation energies suggest that these LB→GaI systems are capable of forming stable donor-acceptor complexes with group 13 trichlorides. Examination of the ligand exchange reactions with iron and nickel complexes indicates their potential use as ligands in transition metal chemistry. In addition, it is found that the title compounds are also able to activate various enthalpically robust bonds. Further, a detailed mechanistic investigation of these small molecule activation processes reveals the non-innocent behavior of the carbene (base) moiety attached to the GaI fragment, thereby indicating the cooperative nature of these bond activation processes. The energy decomposition analysis (EDA) and activation strain model (ASM) of reactivity were also employed to quantitatively understand and rationalize the different activation processes.

Solvent role in molecular structure level, structural and topology investigations, molecular docking and antimicrobial activity studies on sulpha drug derivative

The Schiff base (5FSATH) was synthesized and characterized by different experimental techniques. In the context of local energy decomposition analysis (LED), the binding energy of 5FSATH-water interaction is determined to be -15.63 kcal/mol, while the bond distance between the two objects is measured to be 1.9781 A°. The absorption spectrum was recorded using different solvents like DMSO, water, and chloroform. The experimental absorption spectrum wavelengths 206, 220, and 300 nm, were recorded from DMSO solvent. In the emission (fluorescence) spectrum we observed three different wavelengths such as 352, 510, and 609 nm. For the calculated NMR spectrum, used the standard GIAO method and DMSO as the solvent. The HOMO-LUMO analysis indicates the charge transfer within the molecule, it is calculated by different solvents. NBO confirms the synthesized compound stability, hyper conjugative interaction, and charge delocalization. To test for antibacterial and antifungal activity, an agar disc well diffusion method is utilized. Synthesized compound tested against Escherichia coli, Candida albicans, Staphylococcus aureus, and Streptococcus pneumoniae microorganisms. Amoxicillin was used as the reference drug for testing antibacterial and antifungal activity. According to the findings of the antimicrobial activity, the result of the molecular docking experiment showed that the compound 5FSATH had an extremely high binding affinity score.

A facile synthesis, characterization, DFT, ADMET and in-silico molecular docking analysis of novel 4-ethyl acridine-1,3,9 (2,4,10H)-trione

A novel synthetic reaction was employed to produce an acridine derivative of 4-ethyl acridine-1,3,9 (2,4,10H)-trione. The structural characterizations of the synthesized compound were confirmed through FT-IR, NMR 1H,13C, and GC-Mass spectral data. Furthermore, the DFT approaches were performed to the vibrational wavenumbers obtained through simulation with experimental wave numbers. The Vibrational Energy Distribution Analysis (VEDA) software is employed in FT-IR wave number for conducting potential energy decomposition (PED) analysis. DFT calculations were also applied to optimize the structural parameters and investigate Frontier molecular orbitals (FMOs), molecular electrostatic potentials, RDG studies, and global chemical reactivity descriptors, Natural bond orbital analysis and Non-linear optical properties were obtained for the title compound using the DFT method. Molecular docking studies were conducted to explore the binding mode mechanism of title compound and were evaluated for cancer-related proteins, specifically 4y72. Also, the synthesised compound was evaluated for Drug-likeness, and ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) properties indicating favourable pharmacokinetic profiles with no observed signs of toxicity.

T-Shaped Palladium and Platinum {MNO}10 Nitrosyl Complexes.

The synthesis and characterization of a homologous series of T-shaped {MNO}10 nitrosyl complexes of the form [M(PR3)2(NO)]+ (M = Pd, Pt; R = tBu, Ad) are reported. These diamagnetic nitrosyls are obtained from monovalent or zerovalent precursors by treatment with NO and NO+, respectively, and are notable for distinctly bent M-NO angles of ∼123° in the solid state. Adoption of this coordination mode in solution is also supported by the analysis of isotopically enriched samples by 15N NMR spectroscopy. Effective oxidation states of M0/NO+ are calculated, and metal-nitrosyl bonding has been interrogated using DFT-based energy decomposition analysis techniques. While a linear nitrosyl coordination mode was found to be electronically preferred, the M-NO and P-M-P angles are inversely correlated to the extent that binding in this manner is prevented by steric repulsion between the bulky ancillary phosphine ligands.

The Pivotal Distinction between Antagonists' and Agonists' Binding into Dopamine D4 Receptor-MD and FMO/PIEDA Studies.

The dopamine D4 receptor (D4R) is a promising therapeutic target in widespread diseases, and the search for novel agonists and antagonists appears to be clinically relevant. The mechanism of binding to the receptor (R) for antagonists and agonists varies. In the present study, we conducted an in-depth computational study, teasing out key similarities and differences in binding modes, complex dynamics, and binding energies for D4R agonists and antagonists. The dynamic network method was applied to investigate the communication paths between the ligand (L) and G-protein binding site (GBS) of human D4R. Finally, the fragment molecular orbitals with pair interaction energy decomposition analysis (FMO/PIEDA) scheme was used to estimate the binding energies of L-R complexes. We found that a strong salt bridge with D3.32 initiates the inhibition of the dopamine D4 receptor. This interaction also occurs in the binding of agonists, but the change in the receptor conformation to the active state starts with interaction with cysteine C3.36. Such a mechanism may arise in the case of agonists unable to form a hydrogen bond with the serine S5.46, considered, so far, to be crucial in the activation of GPCRs. The energy calculations using the FMO/PIEDA method indicate that antagonists show higher residue occupancy of the receptor binding site than agonists, suggesting they could form relatively more stable complexes. Additionally, antagonists were characterized by repulsive interactions with S5.46 distinguishing them from agonists.

Binding Affinity and Mechanism of Six PFAS with Human Serum Albumin: Insights from Multi-Spectroscopy, DFT and Molecular Dynamics Approaches.

Per- and Polyfluoroalkyl Substances (PFAS) bioaccumulate in the human body, presenting potential health risks and cellular toxicity. Their transport mechanisms and interactions with tissues and the circulatory system require further investigation. This study investigates the interaction mechanisms of six PFAS with Human Serum Albumin (HSA) using multi-spectroscopy, DFT and a molecular dynamics approach. Multi-spectral analysis shows that perfluorononanoic acid (PFNA) has the best binding capabilities with HSA. The order of binding constants (298 K) is as follows: "Perfluorononanoic Acid (PFNA, 7.81 × 106 L·mol-1) > Perfluoro-2,5-dimethyl-3,6-dioxanonanoic Acid (HFPO-TA, 3.70 × 106 L·mol-1) > Perfluorooctanoic Acid (PFOA, 2.27 × 105 L·mol-1) > Perfluoro-3,6,9-trioxadecanoic Acid (PFO3DA, 1.59 × 105 L·mol-1) > Perfluoroheptanoic Acid (PFHpA, 4.53 × 103 L·mol-1) > Dodecafluorosuberic Acid (DFSA, 1.52 × 103 L·mol-1)". Thermodynamic analysis suggests that PFNA and PFO3DA's interactions with HSA are exothermic, driven primarily by hydrogen bonds or van der Waals interactions. PFHpA, DFSA, PFOA, and HFPO-TA's interactions with HSA, on the other hand, are endothermic processes primarily driven by hydrophobic interactions. Competitive probe results show that the main HSA-PFAS binding site is in the HSA structure's subdomain IIA. These findings are also consistent with the findings of molecular docking. Molecular dynamics simulation (MD) analysis further shows that the lowest binding energy (-38.83 kcal/mol) is fund in the HSA-PFNA complex, indicating that PFNA binds more readily with HSA. Energy decomposition analysis also indicates that van der Waals and electrostatic interactions are the main forces for the HSA-PFAS complexes. Correlation analysis reveals that DFT quantum chemical descriptors related to electrostatic distribution and characteristics like ESP and ALIE are more representative in characterizing HSA-PFAS binding. This study sheds light on the interactions between HSA and PFAS. It guides health risk assessments and control strategies against PFAS, serving as a critical starting point for further public health research.

VIV of two rigidly coupled side-by-side cylinders at subcritical [formula omitted

Cross-flow vortex-induced vibration (VIV) of two rigidly coupled circular cylinders in side-by-side arrangement at a Reynolds number of 1000 is numerically investigated using direct numerical simulation. A low mass ratio of 1.27 is considered and the nondimensional centre-to-centre spacing ratio is fixed at 2.0. The reduced velocity ranges from 2 to 13. Three response branches are identified and these responses result in different wake and hydrodynamic characteristics. The cases with large amplitudes feature the co-shedding and lower pressure in the gap, while those with small amplitudes are characterised by two parallel vortex streets. Characterisation and quantification of the flow fields of two rigidly coupled side-by-side cylinders undergoing VIV, which have seldom been reported in the existing research, are elaborated on in this study via the statistical analysis in terms of the turbulent wake visualisation, Reynolds stresses, turbulence kinetic energy (TKE) and proper orthogonal decomposition (POD) analysis. It is found that the cases with large amplitudes show a more unstable wake with sharp increases in the Reynolds stresses and TKE in the near wake. Moreover, the large amplitudes are seen to weaken the asymmetry of the wake and the initial POD modes are more energetic. A reformulated version of the novel force decomposition technique is used to realise the measurement of the time-dependent contributions from each mode to the pressure drag. The large amplitude cases are associated with the drag mode and the lift mode, whereas three modes are observed as the amplitude decreases.

Mechanistic study of the transmission pattern of the SARS-CoV-2 omicron variant.

The omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) characterized by 30 mutations in its spike protein, has rapidly spread worldwide since November 2021, significantly exacerbating the ongoing COVID-19 pandemic. In order to investigate the relationship between these mutations and the variant's high transmissibility, we conducted a systematic analysis of the mutational effect on spike-angiotensin-converting enzyme-2 (ACE2) interactions and explored the structural/energy correlation of key mutations, utilizing a reliable coarse-grained model. Our study extended beyond the receptor-binding domain (RBD) of spike trimer through comprehensive modeling of the full-length spike trimer rather than just the RBD. Our free-energy calculation revealed that the enhanced binding affinity between the spike protein and the ACE2 receptor is correlated with the increased structural stability of the isolated spike protein, thus explaining the omicron variant's heightened transmissibility. The conclusion was supported by our experimental analyses involving the expression and purification of the full-length spike trimer. Furthermore, the energy decomposition analysis established those electrostatic interactions make major contributions to this effect. We categorized the mutations into four groups and established an analytical framework that can be employed in studying future mutations. Additionally, our calculations rationalized the reduced affinity of the omicron variant towards most available therapeutic neutralizing antibodies, when compared with the wild type. By providing concrete experimental data and offering a solid explanation, this study contributes to a better understanding of the relationship between theories and observations and lays the foundation for future investigations.

In Vitro and In Silico Studies on Benzimidazole‐Based Compounds

AbstractColon cancer remains a significant health concern, necessitating the synthesis of novel therapeutic agents. Benzimidazole derivatives have shown promising anticancer potential. In this study, two benzimidazole derivatives were synthesized, and their antiproliferative activities were investigated in vitro against the human colon colorectal cancer cell line and the human normal lung fibroblast cell line. The cell viability revealed that molecule 3 had high antiproliferative activity and inhibited the growth of DLD‐1 cells for 48 h. Furthermore, molecule 3 was found to have more selectivity against the human normal cell line. Computational calculations were performed to predict the molecular properties of molecules using the B3LYP/6‐311++(2d,2p) density functional theory level. The quantum theory of atoms in molecules (QTAIM) and energy decomposition analysis (EDA) were utilized to investigate the nature of the interatomic bonding existing among the studied molecules. The ultraviolet‐visible (UV–vis) results for molecules were calculated using time‐dependent density‐functional theory (TD‐DFT). The chemical reactivity and molecular stability were also investigated by DFT computational analysis. The molecular docking and dynamics simulations were conducted, and their results reveal their concordance with the experimental results. Molecule 3 has better anti‐cancer activity against colon cancer targets (PDB ID: 2HQ6) compared to molecule 2.

Insight into the nature of carbon-metal bonding for N-heterocyclic carbenes in gold/silver complexes and nanoparticles using DFT-correlated Raman spectroscopy: strong evidence for π-backbonding.

N-Heterocyclic carbenes (NHCs) have emerged as promising ligands for stabilizing metallic complexes, nanoclusters, nanoparticles (NPs) and surfaces. The carbon-metal bond between NHCs and metal atoms plays a crucial role in determining the resulting material's stability, reactivity, function, and electronic properties. Using Raman spectroscopy coupled with density functional theory calculations, we investigate the nature of carbon-metal bonding in NHC-silver and NHC-gold complexes as well as their corresponding NPs. While low wavenumbers are inaccessible to standard infrared spectroscopy, Raman detection reveals previously unreported NHC-Au/Ag bond-stretching vibrations between 154-196 cm-1. The computationally efficient r2SCAN-3c method allows an excellent correlation between experimental and predicted Raman spectra which helps calibrate an accurate description of NHC-metal bonding. While π-backbonding should stabilize the NHC-metal bond, conflicting reports for the presence and absence of π-backbonding are seen in the literature. This debate led us to further investigate experimental and theoretical results to ultimately confirm and quantify the presence of π-backbonding in these systems. Experimentally, an observed decrease in the NHC's CN stretching due to the population of the π* orbital is a good indication for the presence of π-backbonding. Using energy decomposition analysis - natural orbitals for chemical valence (EDA-NOCV), our calculations concur and quantify π-backbonding in these NHC-bound complexes and NPs. Surprisingly, we observe that NPs are less stabilized by π-backbonding compared to their respective complexes-a result that partially explains the weaker NHC-NP bond. The protocol described herein will help optimize metal-carbon bonding in NHC-stabilized metal complexes, nanoparticles and surfaces.

Theoretical prediction of donor-acceptor type novel complexes with strong noble gas-boron covalent bond.

The experimental identification of NgBeO molecules, followed by the recent theoretical exploration of super-strong NgBO+ (Ng = He-Rn) ions motivated us to investigate the stability of iso-electronic NgBNH+ (Ng = He-Rn) ions using various ab initio-based quantum chemical methods. The hydrogen-like chemical behavior of gold in small clusters and molecules also inspired us to study the nature of the bonding interactions in NgBNAu+ ions compared to that in NgBNH+ ions. The calculated Ng-B bond lengths in the predicted ions have been found to be much lower than the corresponding covalent limits, indicating a covalent Ng-B interaction in both the NgBNH+ and NgBNAu+ ions. In addition, the Ng-B bond dissociation energies are found to be in the range of 136.7-422.8 kJ mol-1 for NgBNH+ and 77.4-319.1 kJ mol-1 for NgBNAu+, implying the stable nature of the predicted ions. Interestingly, the Ng-B bond length (except for Ne) is the lowest reported to date together with the highest He-B and Ne-B binding energies considering all the neutral and cationic complexes containing Ng-B bonding motifs. Moreover, the natural bonding orbital (NBO) and electron density-based atoms-in-molecule (AIM) analysis reveal the covalent nature of the Ng-B bond in the predicted ions. Furthermore, the energy decomposition analysis together with the natural bond orbital in the chemical valence (EDA-NOCV) studies indicate that the orbital interaction energy is the main contributor to the total attraction energy in the Ng-B bonds. All the calculated results indicate the hydrogen-like chemical behavior of gold in the predicted NgBNM+ ions, showing further evidence of the concept of "gold-hydrogen analogy". Also, for comparison, the corresponding Cu and Ag analogs are investigated. All the computed results together with the experimental identification of the NgMX (Ng = Ar-Xe; M = Cu, Ag, Au; X = F, Cl), ArOH+, and NgBeO (Ng = Ar-Xe) systems clearly indicate that it may be possible to prepare and characterize the predicted NgBNM+ ions experimentally using suitable technique(s).

Pentacycloundecanylidene and pentacycloundecanone - hyperconjugatively stabilized carbene and ketone.

Pentacycloundecanylidene was spectroscopically identified during the photolysis of the corresponding aziridine and its aerial oxidation results in the corresponding ketone. Here we report the role of hyperconjugative interactions in stabilizing the singlet pentacycloundecanylidene and its corresponding ketone pentacycloundecanone. The pentacycloundecanylidene possesses a singlet ground state with two possible geometrical isomers based on the orientation of the carbene bridge (U1 and U2). The energy difference between U1 and U2 is minimal (0.9 kcal mol-1) and the triplet state is 5.6 kcal mol-1 energetically higher than the more stable singlet state U1. The proximal C-C bonds of the carbene bridge in the singlet state are significantly elongated as compared to the distal C-C bonds. The bending of the carbene bridge in the triplet state and the carbonyl group in the ketone are minimal as compared to the parent pentacycloundecane. The molecular orbital (MO), natural bond orbital (NBO) and energy decomposition analysis (EDA) show that both Cieplak-type hyperconjugation viz. donation of electrons from the proximal C-C σ bonds to the empty p-orbital on the carbene centre and Felkin-Anh type hyperconjugation viz. donation of the lone pair of carbene carbon to the distal C-C σ* orbitals exist in carbene systems. The bending of the carbene bridge in singlet carbene is to enhance the Cieplak-type hyperconjugative interaction. The ketone is also stabilized by Cieplak-type hyperconjugative interaction but to a lower extent as compared to the singlet carbene. The reactivity study suggests that the singlet pentacycloundecanylidene is ambiphilic in nature.

Computational study of core modified dipyriamethyrin for the competitive complexation of Am3+/Cm3+ from their trichlorides.

In the process of handling and storage of radioactive actinides it is essential to selectively sequester the minor actinides, such as Am and Cm, through a competitive complexation process. Herein we computationally designed two core modified ligands (L21- and L3) through systematic oxygen substitution at the NH sites of dipyriamethyrin (L1_2H), a hexadentate expanded porphyrin, and studied their competitive complexation towards trivalent actinides (An = Am/Cm) from their trichlorides using density functional theory (DFT). We observed shorter An-N bonds and longer An-O bonds in complexes based on core modified ligands (L21- and L3). The An-Cl bond length increases with increasing axial coordination number (i.e., from L12- to L3) to accommodate the ligands. All the bonds were identified to be electrostatic in nature. L12- exhibits shorter bonds and larger bond orders on complexing with Am than with Cm. On moving from complexes of L21- to L3, the An-N bond lengths are shortened, while An-O bond lengths become larger. Between the complexes of Am and Cm, there is marginal difference in their bond distances with L21- and L3. Charge analysis shows ligand to metal charge transfer during coordination, with back-donation from An to N/O and Cl. The calculated spin-density analysis indicates that An remains in its trivalent oxidation state on complexation, while orbital occupation analysis shows that the 5f and 6d orbitals are involved in bonding; this was confirmed by molecular orbital (MO) analysis that shows the complexes of L21- and L3 to exhibit higher degeneracy in their overlapping MOs. Further, the energy decomposition analysis (EDA) confirms that all ionic bonds are primarily due to electrostatic contributions, where the orbital contributions increase from L12- to L3 complexes and maximum covalency was observed in Cm complexes due to the energy matching between the 5f orbitals of Cm and the 2p orbitals of N and Cl, compared to Am. To confirm the competitiveness in the complexation of the ligand towards Am vs. Cm, the thermodynamic parameters were analysed for the ligand and metal substitution reactions. L12- shows more affinity towards Am than Cm, while L21- and L3 prefer Cm.

Substituted fullerenes as a promising capping ligand towards stabilization of exohedral Dy(III) based single-ion magnets: a theoretical study.

Organometallic dysprosocenium-based molecular magnets are the forefront runners in offering giant magnetic anisotropy and blocking temperatures close to the boiling point of liquid nitrogen. Attaining linearity in the organometallic dysprosocenium complexes is the key to generating giant magnetic anisotropy and blocking barriers. In the present study, we have unravelled the coordination ability of the substituted fullerene (C55X5)- (where X = CCH3, B, and N) generated by fencing around the five-membered ring of fullerene towards stabilizing a new family of exohedral dysprosium organometallic complexes showcasing giant magnetic anisotropy and blockade barriers. Eight exohedral mononuclear dysprosium organometallic complexes, namely [Dy(η5-C55X5)(η4-C4H4)] (1), [Dy(η5-C55X5)(η5-Cp)]+ (2), [Dy(η5-C55X5)(η5-Cp*)]+ (3), [Dy(η5-C55X5)(η6-C6H6)]2+ (4), [Dy(η5-C55X5)(η8-C8H8)] (5), [Dy(η5-C55X5)2]+ (6) (where X = CCH3), [Dy(η5-C55B5)2]+ (7) and [Dy(η5-C55N5)2]+ (8), were studied using scalar relativistic density functional theory (SR-DFT) and the complete active space self-consistent field (CASSCF) methodology to shed light on the structure, stability, bonding and single-ion magnetic properties. SR-DFT calculations predict complexes 1-8 to be highly stable, with a strictly linear geometry around the Dy(III) ion in complexes 6-8. Energy Decomposition Analysis (EDA) predicts the following order for interaction energy (ΔEint value): 5 > 1 > 2 ≈ 3 > 6 > 7 > 8 > 4, with sizable 4f-ligand covalency in all the complexes. CASSCF calculations on complexes 1-8 predict stabilization of mJ |±15/2〉 as the ground state for all the complexes except for 5, with the following trend in the Ucal values: 6 (1573 cm-1) ≈ 3 (1569 cm-1) > 1 (1538 cm-1) > 8 (1347 cm-1) > 2 (1305 cm-1) > 7 (1284 cm-1) > 4 (1125 cm-1) > 5 (108 cm-1). Ab initio ligand field theory (AILFT) analysis provides a rationale for Ucal ordering, where π-type 4f-ligand interactions in complexes 1-4 and 6-8 offer giant barrier height while the large (C8H8)2- rings generate δ-type interaction in 5, which diminishes the axiality in the ligand field. Our detailed finding suggests that the exohedral organometallic dysprosocenium complexes are more linear compared to bent [DyCp*2]+ cations and display a giant barrier height exceeding 1500 cm-1 with negligible quantum tunnelling of magnetization (QTM) - a new approach to design highly anisotropic dysprosium organometallic complexes.

In silico modelling of chelate stabilized tetrylene derivatives.

The steric and electronic effects of specific ligands can play crucial roles in stabilizing unsaturated tetrylene species. In this work, hybrid density functional theory (DFT) methods, quantum theory of atoms in molecules (QTAIM) investigations and natural bond orbital (NBO) calculations are employed to evaluate the stabilization of low-valent E(ii) centers (E = Si, Ge, Sn, Pb) through the chelating effect generated by an electron-rich ligand containing the P[double bond, length as m-dash]C-P[double bond, length as m-dash]X moiety (X = O or S). Based on several types of analyses, such as the bond dissociation energy (BDE) or the interplay between attractive (i.e., charge-transfer) and repulsive (i.e., Pauli-exchange) effects, we highlight that the stabilization energy induced by chelation is up to ca. 70 kcal mol-1 for silylenes, yet slightly decreases within the heavier analogues. Moreover, it is emphasized that chelate-stabilized silylenes can form highly stable hybrid metal-metalloid complexes with transition metals (e.g., gold). Due to push-pull effects occurring in the X→Si(ii)→Au fragment, the Si(ii)→Au bonding is significantly stronger than the X→Au, P(sp2)→Au or π(C[double bond, length as m-dash]P)→Au donor-acceptor bonds, which are potentially formed by the electron-rich P[double bond, length as m-dash]C-P[double bond, length as m-dash]X unit with the AuCl fragment. These findings are supported by energy decomposition analysis (EDA) calculations.

High-valent actinyl (AnO2; An = U, Np and Pu) complexation with TEtraQuinoline (TEQ) ligand - a DFT study.

A recently synthesised novel macrocycle composed of four quinoline units called TEtraquinoline (TEQ) (J. Am. Chem. Soc., 2023, 145(4), 2609-2618) was reported to exhibit transition metal complexation ability. Meanwhile, there is a growing interest in different binding motifs for radioactive and toxic actinides. In this study, we modelled high-valent actinyl (AnO2)n+, An = U, Np, Pu; n = 1, 2, 3 complexes of TEQ and studied their geometric and electronic properties using scalar relativistic density functional theory (SR-DFT). The calculated results showed that the equatorial An-N and axial AnO bonds were polar bonds with a high degree of covalence, the former being longer than the latter. Natural bond orbital (NBO) analysis of the An-N bond orders decreased from complexes of uranyl to plutonyl and from complexes of heptavalent to pentavalent actinyls. This was due to the localization of the 5f orbital in the heavier actinyl and the high charge on An. The charge analysis showed a ligand-to-metal charge transfer (LMCT) on complexation. It was interesting to observe metal-to-ligand spin delocalization only in the [AnVI/VIIO2L]2+/3+ complexes, where the spin density on An was observed to increase on complexation. Based on the assigned oxidation states, it was observed that the heptavalent neptunyl cation retained its formal high oxidation state on complexation with TEQ. The energetics associated with the formation reaction of all the actinyl-TEQ complexes suggest spontaneity at lower temperatures (i.e., lower than 298.15 K). The energy decomposition analysis (EDA) indicates that the electrostatic energy contributions were predominant in the [AnVO2L]+ complexes, while covalent (orbital) energy contributions were higher in the [AnVIO2L]2+ and [AnVIIO2L]3+ complexes. The extended transition state-natural orbitals for chemical valence (ETS-NOCV) analysis confirmed the prominent covalent character in [AnVIIO2L]3+ over [AnVIO2L]2+ and [AnVO2L]+and the back donation of charges from An to N that stabilizes TEQ.

A many-body energy decomposition analysis (MB-EDA) scheme based on a target state optimization self-consistent field (TSO-SCF) method.

In this paper, we combine an energy decomposition analysis (EDA) scheme with many-body expansion (MBE) to develop a MB-EDA method to study the cooperative and anti-cooperative effects in molecular cluster systems. Based on the target state optimization self-consistent field (TSO-SCF) method, the intermolecular interaction energy can be decomposed into five chemically meaningful terms, i.e., electrostatic, exchange, polarization, charge transfer and dispersion interaction energies. MB-EDA can decompose each of these terms in MBE. This MB-EDA has been applied to 3 different cluster systems: water clusters, ionic liquid clusters, and acetonitrile-methane clusters. This reveals that electrostatic, exchange, and dispersion interactions are highly pairwise additive in all systems. In water and ionic liquid clusters, the many-body effects are significant in both polarization and charge transfer interactions, but are cooperative and anti-cooperative, respectively. For acetonitrile-methane clusters, which do not involve hydrogen bonds or charge-charge Coulombic interactions, the many-body effects are quite small. The chemical origins of different many-body effects are deeply analyzed. The MB-EDA method has been implemented in Qbics (https://qbics.info) and can be a useful tool for understanding the many-body behavior in molecular aggregates at the quantum chemical level of theory.

Superhalogens inside fullerenes X@C2n (X = BO2, BeF3; 2n = 60, 70).

The exploration of endohedral fullerenes has garnered significant attention recently due to their distinctive chemical, electrochemical, and optoelectronic properties. Charge transfer, which usually occurs from encapsulated species to fullerenes, importantly affects the structures and properties of endohedral fullerenes. In this study, we theoretically investigated endohedral superhalogen fullerenes X@C2n (X = BO2, BeF3; 2n = 60, 70), in which the charge is reversely transferred from the fullerene to the superhalogen, by using density functional theory calculations and ab initio molecular dynamics simulations. Both natural population analysis and the quantum theory of atoms in molecules confirm about one electron transfer from the fullerene to the superhalogen, resulting in the formal valence state of X-@C2n+. Energy decomposition analysis on the interaction between the superhalogen and fullerene revealed that electrostatic energy contributes predominantly to the total interaction energy. These endohedral superhalogen fullerenes with cationic fullerenes were predicted to be able to serve as building blocks for one dimensional fullerene-based nanowires when combined with endohedral alkali-metallofullerenes with anionic fullerenes.