Anion Photoelectron Spectroscopy and Quantum Chemistry Calculations of Gas-Phase TaSi17Ì and TaSi18Ì Clusters: Structural Determination, Bonding Characteristics, and Multiplicity of Structural Forms.

This study explores the structures and chemical bonding properties of TaSi17̅ and TaSi18̅ clusters by employing anion photoelectron spectroscopy and theoretical computations. Utilizing CALYPSO and ABCluster programs for initial structure prediction, B3LYP hybrid functional for optimization, and CCSD(T)/def2-TZVPPD level for energy calculations, the research identifies the most stable isomers of these clusters. Key findings include the identification of two coexisting low-energy isomers for TaSi17̅, exhibiting Ta-endohedral fullerene-like cage structures, and the lowest-energy structures of TaSi17̅ and TaSi18̅ anions can be considered as derived from the TaSi16̅ superatom cluster. The study enhances the understanding of group 14 element chemistry and guides the design of novel inorganic metallic compounds, potentially impacting materials science.

Unveiling the structural and bonding properties of AuSi2- and AuSi3- clusters: A comprehensive analysis of anion photoelectron spectroscopy and ab initio calculations.

Silicon clusters infused with transition metals, notably gold, exhibit distinct characteristics crucial for advancing microelectronics, catalysts, and energy storage technologies. This investigation delves into the structural and bonding attributes of gold-infused silicon clusters, specifically AuSi2- and AuSi3-. Utilizing anion photoelectron spectroscopy and ab initio computations, we explored the most stable isomers of these clusters. The analysis incorporated Natural Population Analysis, electron localization function, molecular orbital diagrams, adaptive natural density partitioning, and Wiberg bond index for a comprehensive bond assessment. Our discoveries reveal that cyclic configurations with the Au atom atop the Si-Si linkage within the fundamental Si2 and Si3 clusters offer the most energetically favorable structures for AuSi2- and AuSi3- anions, alongside their neutral counterparts. These anions exhibit notable highest occupied molecular orbital-lowest unoccupied molecular orbital gaps and significant σ and π bonding patterns, contributing to their chemical stability. Furthermore, AuSi2- demonstrates π aromaticity, while AuSi3- showcases a distinctive blend of σ antiaromaticity and π aromaticity, crucial for their structural robustness. These revelations expand our comprehension of gold-infused silicon clusters, laying a theoretical groundwork for their potential applications in high-performance solar cells and advanced functional materials.

Structural evolution and bonding properties of Nb1-2Gen-/0 (n = 3-7) clusters: Anion photoelectron spectroscopy and theoretical calculations.

This study presents a collaborative experimental and theoretical investigation into the structures and electronic properties of niobium-doped germanium clusters. Anion photoelectron spectra for Nb1-2Gen- (n = 3-7) clusters were acquired using 266 nm photon energies, enabling the determination of adiabatic detachment energies and vertical detachment energies. In conjunction with these experimental measurements, density functional theory (DFT) calculations were conducted to validate the experimentally obtained electron detachment energies and elucidate the geometric and electronic structures of each anionic cluster. The agreement between DFT calculations and experimental data establishes a solid foundation for assessing the structural evolution and electronic properties of niobium-doped germanium clusters. It is noted that both neutral and anionic clusters exhibit predominantly similar overall structural characteristics, with the exception of Nb2Ge6- and Nb2Ge6. Furthermore, this investigation emphasizes the exceptional chemical stability of the D3d symmetric chair-shaped structure in Nb2Ge6-, providing insights into its bonding characteristics.

Targeting mitochondrial shape: at the heart of cardioprotection.

There remains an unmet need to identify novel therapeutic strategies capable of protecting the myocardium against the detrimental effects of acute ischemia-reperfusion injury (IRI), to reduce myocardial infarct (MI) size and prevent the onset of heart failure (HF) following acute myocardial infarction (AMI). In this regard, perturbations in mitochondrial morphology with an imbalance in mitochondrial fusion and fission can disrupt mitochondrial metabolism, calcium homeostasis, and reactive oxygen species production, factors which are all known to be critical determinants of cardiomyocyte death following acute myocardial IRI. As such, therapeutic approaches directed at preserving the morphology and functionality of mitochondria may provide an important strategy for cardioprotection. In this article, we provide an overview of the alterations in mitochondrial morphology which occur in response to acute myocardial IRI, and highlight the emerging therapeutic strategies for targeting mitochondrial shape to preserve mitochondrial function which have the future therapeutic potential to improve health outcomes in patients presenting with AMI.

Structural Determination and Bonding Characteristics of the Gas-Phase Ta2Si2Ì Anion and Its Neutral: Anion Photoelectron Spectroscopy and Theoretical Studies.

The structures and bonding characteristics of Ta2Si2̅/0 clusters are investigated using anion photoelectron spectroscopy and quantum chemical calculations. The vertical detachment energy of the Ta2Si2̅ anion is measured to be 2.00 ± 0.08 eV using the 266 nm photon. It is found that the Ta2Si2̅ anion has three low-energy isomers with a C2v symmetric Ta-Ta dibridged structural framework, all of which contribute to the experimental photoelectron spectrum, while the Ta2Si2 neutral also has a C2v symmetric Ta-Ta dibridged structural framework. The charge-transfer from Ta atoms to Si atoms is discovered using atomic dipole moment corrected Hirshfeld analysis for the Ta2Si2̅ anion and Ta2Si2 neutral. Chemical bonding investigations show that both the Ta2Si2̅ anion and Ta2Si2 neutral have a strong covalent Ta-Ta bond, as well as σ and π double bonding patterns. Furthermore, the Ta atoms are linked together by a single 2c-2e Ta2 σ bond, whereas the Si atoms are linked together with the Ta atoms via four 2c-2e TaSi σ bonds, two 3c-2e TaSi2 σ bonds, one 4c-2e Ta2Si2 σ bond, and one 4c-2e Ta2Si2 π bond.

Structure determination and bonding properties of gas-phase OPt2- anion and its neutral form.

Using anion photoelectron spectroscopy and quantum chemical calculations, the structures and properties of OPt2-/0 are investigated. The vertical detachment energies (VDEs) of OPt2- are measured to be 3.28 eV and 3.23 eV through the use of 355 and 266 nm photons, respectively. The high experimental VDEs of OPt2- can be attributed to the strong Pt-Pt and Pt-O σ bonds and low orbital energy of the SOMO. It is found that neutral OPt2 has an OPt2 triangular structure with C2v symmetry and 1A1 electronic state. In the neutral OPt2, the O atom interacts with the Pt2 moiety by two 2c-2e PtO bonds, one 3c-2e Pt2O σ bond, and one 3c-2e Pt2O π bond. On the other hand, anionic OPt2 adopts a Pt-Pt-O bent structure with Cs symmetry and 2A' electronic state. NPA and ELF analyses indicate charge transfer upon complexation from the metal atoms to the O atom. Chemical bonding analyses show that OPt2-/0 have the strong covalent Pt-Pt and Pt-O bonds, and neutral OPt2 exhibits σ aromaticity and π antiaromaticity.

Postoperative complications after gastrointestinal pediatric surgical procedures: outcomes and socio-demographic risk factors.

BACKGROUND: Several socio-demographic characteristics are associated with complications following certain pediatric surgical procedures. In this comprehensive study, we sought to determine socio-demographic risk factors and resource utilization of children with complications after common pediatric surgical procedures. METHODS: We performed a population-based cohort study utilizing the 2016 Healthcare Cost and Use Project Kids' Inpatient Database (KID) to identify and characterize pediatric patients (age 0-21 years) in the United States with common inpatient pediatric gastrointestinal surgical procedures: appendectomy, cholecystectomy, colonic resection, pyloromyotomy and small bowel resection. Multivariable logistic regression modeling was used to identify socio-demographic predictors of postoperative complications. Length of stay and hospitalization costs for patients with and without postoperative complications were compared. RESULTS: A total of 66,157 pediatric surgical hospitalizations were identified. Of these patients, 2,009 had postoperative complications. Male sex, young age, African American and Native American race and treatment in a rural hospital were associated with significantly greater odds of postoperative complications. Mean length of stay was 4.58 days greater and mean total costs were $11,151 (US dollars) higher in the complication cohort compared with patients without complications. CONCLUSIONS: Postoperative complications following inpatient pediatric gastrointestinal surgery were linked to elevated healthcare-related expenditure. The identified socio-demographic risk factors should be considered in the risk stratification before pediatric surgical procedures. Targeted interventions are required to reduce preventable complications and surgical disparities.

Structural Determination and Bonding Properties of Gas-Phase Ternary [O, Ta, 2C]- Anions.

A combined anion photoelectron spectroscopic and quantum chemical investigation was performed to explore the structures and bonding properties of ternary [O, Ta, 2C]- anions. The atomic bonding connectivity of the ternary anion was found to be (O-Ta-C2)- rather than (Ta-O-C2)-. The photoelectron spectrum using 266 nm photons was measured, and the theoretical simulated spectrum was calculated, with good agreement between experimental and theoretical results being found. Computations obtained electronic energies and low-energy structures and enabled chemical bonding analyses. The experimental vertical detachment energies of OTaC2- were measured to be 2.85 ± 0.08 eV. OTaC2- exhibits π aromaticity with two delocalized π electrons and σ antiaromaticity.

Evaluating hemoptysis hospitalizations among patients with bronchiectasis in the United States: a population-based cohort study.

BACKGROUND: The burden of hospitalizations and mortality for hemoptysis due to bronchiectasis is not well characterized. The primary outcome of our study was to evaluate in-hospital mortality in patients admitted with hemoptysis and bronchiectasis, as well as the rates of bronchial artery embolization, length of stay, and hospitalization costs. METHODS: The authors queried the Nationwide Inpatient Sample (NIS) claims database for hospitalizations between 2016 and 2017 using the ICD-10-CM codes for hemoptysis and bronchiectasis in the United States. Multivariable regression was used to evaluate predictors of in-hospital mortality, embolization, length of stay, and hospital costs. RESULTS: There were 8240 hospitalizations (weighted) for hemoptysis in the United States from 2016 to 2017. The overall in-hospital mortality was 4.5%, but higher in males compared to females. Predictors of in-hospital mortality included undergoing three or more procedures, age, and congestive heart failure. Bronchial artery embolization (BAE) was utilized during 2.1% of hospitalizations and was more frequently used in those with nontuberculous mycobacteria and aspergillus infections, but not pseudomonal infections. The mean length of stay was 6 days and the median hospitalization cost per patient was USD $9,610. Having comorbidities and procedures was significantly associated with increased length of stay and costs. CONCLUSION: Hemoptysis is a frequent indication for hospitalization among the bronchiectasis population. In-hospital death occurred in approximately 4.5% of hospitalizations. The effectiveness of BAE in treating and preventing recurrent hemoptysis from bronchiectasis needs to be explored.

Clinical characteristics and outcomes for paediatric patients admitted with congenital or acquired syphilis: a population-based cohort study.

OBJECTIVES: Paediatric congenital and acquired syphilis cases have been increasing since 2012 in the USA. Potential differences in associated hospitalisation trends and healthcare utilisation between the two syphilis entities have not yet been assessed. We sought to compare these entities and describe their clinical characteristics, distribution and impact in the USA. METHODS: We conducted a population-based cohort study using the 2016 Kids' Inpatient Database (KID) to identify and characterise syphilis-associated hospitalisations among paediatric patients (age 0-21 years) in the USA during the year of 2016. Length of stay and hospitalisation costs for patients with congenital and acquired syphilis were compared in multivariable models. RESULTS: A total of 1226 hospitalisations with the diagnosis of syphilis were identified. Of these patients, 958 had congenital syphilis and 268 were acquired cases. The mean cost of care for congenital syphilis was $23 644 (SD=1727), while the treatment of a patient with acquired syphilis on average cost $10 749 (SD=1966). Mean length of stay was 8 days greater and mean total costs were $12 895 (US dollars) higher in the congenital syphilis cohort compared with the acquired syphilis cohort. In congenital syphilis, there were greater frequency of cases in the Southern and Western regions of the USA (p<0.001). CONCLUSION: Congenital syphilis was associated with greater healthcare-related expenditure than acquired syphilis in paediatric patients. In addition to improving patient outcomes, congenital syphilis prevention efforts may significantly reduce healthcare utilisation burden and cost.

Structural evolution from exohedral to endohedral geometries, dynamical fluxionality, and structural forms of medium-sized anionic and neutral Au2Sin (n = 8-20) clusters.

The structural evolution of medium-sized anionic and neutral Au2Sin (n = 8-20) clusters is investigated by using density functional theory (DFT) calculations and CCSD(T) methods in combination with the particle swarm optimization (CALYPSO) global search algorithm. The geometries of anionic and neutral Au2Sin clusters change from exohedral to endohedral ones with the increasing cluster sizes, and the critical size of forming Au2-endohedral structures for both anionic and neutral clusters is confirmed to be n = 20, in which a C2h symmetric Au2-endohedral cage-like structure is observed. Anionic and neutral Au2Sin clusters are primarily dominated by prism-based geometries with most of them adopting different structural features. It is found that the two Au atoms prefer to occupy low coordination sites and interact with fewer Si atoms. The Au atoms carry negative charges because of the electron-transfer from Sin frameworks. Meanwhile, the two Au atoms have very weak interactions. The second-order energy differences and incremental binding energies of anionic and neutral Au2Sin clusters exhibit an odd-even alternation and Au2Si20-/0 clusters are proven to have the highest chemical stability among these Au-Si clusters. Interestingly, Au2Si8-, Au2Si9-, Au2Si13-, Au2Si15-, and Au2Si17- anions, along with Au2Si13, Au2Si14, and Au2Si17 neutrals, have multiplicity of structural forms and their low-lying isomers show dynamical fluxionality due to the low barrier energies.

Structural Evolution and Electronic Properties of TaSin-/0 (n = 2-15) Clusters: Size-Selected Anion Photoelectron Spectroscopy and Theoretical Calculations.

The structural evolution and electronic properties of TaSin-/0 (n = 2-15) clusters are explored using anion photoelectron spectroscopy accompanied by quantum chemical calculations. The Ta atom in TaSin-/0 is inclined to interact with more Si atoms and has high coordination numbers. The theoretical calculations show that TaSi2-/0 have trianglur structures and TaSi3-/0 adopt pyramid structures, while the geometries of TaSin-/0 (n = 4-7) are all exohedral structures dominated by bipyramid-based configurations with the Ta atom face-capping the Sin motifs. TaSi8-/0 and TaSi9-10- have boat-shaped geometries, whereas TaSi9-10 neutrals adopt bipyramid-based geometries instead of boat-shaped ones. TaSi11- and TaSi12 are confirmed as the critical size of transiting from exohedral to endohedral structures for anionic and neutral clusters, respectively. TaSi12-15-/0 have pentagonal or hexagonal prism-based geometries. Natural population analysis shows that the electron transfers from Sin skeletons to Ta atom. The second-order energy differences (Δ2E) and incremental binding energy (ΔEI) values exhibit strong odd-even alternations, suggesting that the TaSin-odd-/0 clusters are more stable than the adjacent TaSin-even-/0 ones, except that TaSi12-/0 are more stable than TaSi11-/0 and TaSi13-/0.

Transition from exohedral to endohedral geometries of anionic and neutral B4Sin (n = 4-15) clusters: quantum chemical calculations.

The growth patterns of anionic and neutral B4Sin (n = 4-15) clusters are investigated by using density functional theory (DFT) calculations combined with particle swarm optimization (CALYPSO) software. The geometries of anionic and neutral B4Sin clusters transform from exohedral to endohedral structures with the increasing cluster sizes. The B4Si14- anion size is critical for forming B4-endohedral structures for anionic clusters, while the B4Si15 neutral size is the threshold size for forming B4-endohedral structures for neutral clusters. Both anionic and neutral B4Sin (n = 4-15) clusters are primarily dominated by prism-based or bipyramid-based geometries. The global minima of anionic and neutral B4Sin clusters adopt different geometrical structures, except for anionic and neutral B4Si10. The binding energies, second-order energy differences, and incremental binding energies of B4Sin- clusters show an odd-even alternation with the growing number of Si atoms. The B atoms in B4Sin-/0 exhibit B-B single bonding and B[double bond, length as m-dash]B double bonding properties. The B atoms are found to carry more negative charges due to charge transfer from Sin frameworks to B atoms. Interestingly, the B4Si4- anion adopts a C2h symmetric bicapped tetragonal bipyramid with σ plus π double bonding characters and has the highest relative stability among the anionic clusters. The bonding interactions in B4Si4- are in the order of B-B > B-Si > Si-Si.

Dynamical fluxionality, multiplicity of structural forms, and electronic properties of the B3Si11 cluster: anion photoelectron spectroscopy and theoretical calculations.

The geometrical structures and electronic properties of anionic, neutral, and cationic B3Si11 clusters were investigated by performing ab initio calculations combined with size-selected anion photoelectron spectroscopy. The experimental photoelectron spectrum of the B3Si11- anion is reasonably reproduced by theoretical simulations of two competing isomers. The global minimum of the B3Si11- anion is formed by the fusion of a B3Si7 bicapped tetragonal antiprism to a B3Si4 pentagonal bipyramid by sharing a B3 triangle, while that of neutral B3Si11 has a B3-endohedral sandwich structure composed of a Si5 five-membered ring and a Si6 six-membered ring, and that of the B3Si11+ cation adopts a Si11 tricapped tetragonal antiprism with three face-capping B atoms. It is interesting that a Si5 five-membered ring and a Si6 six-membered ring are stabilized by three B atoms in B3Si11. The three B atoms tend to bond with each other to form a B3 triangle with stronger B-B bonds than B-Si bonds. Moreover, neutral B3Si11 exhibits σ + π double delocalized bonding patterns. Anionic, neutral, and cationic B3Si11 clusters have multiplicity of structural forms and their low-lying isomers show dynamical fluxionality. The bond lengths, bond orders, MO, constant electronic charge density surfaces, and PDOS analyses showed that the three B atoms in B3Si11 have strong bonding interactions.

Structures and bonding properties of CPt2 -/0 and CPt2H-/0: Anion photoelectron spectroscopy and quantum chemical calculations.

We present a combined anion photoelectron spectroscopic and quantum chemical investigation on the structures and bonding properties of CPt2 -/0 and CPt2H-/0. The experimental vertical detachment energies of CPt2 - and CPt2H- are measured to be 1.91 ± 0.08 and 3.54 ± 0.08 eV, respectively. CPt2 - is identified as a C2v symmetric Pt-C-Pt bent structure, and CPt2 has a D∞h symmetric Pt-C-Pt linear structure. Both anionic and neutral CPt2H adopt a Pt-C-Pt-H chain-shaped structure, in which the ∠PtCPt and ∠CPtH bond angles of CPt2H- are larger than those of CPt2H. The Pt-C bonds in CPt2 -/0 and CPt2H-/0 exhibit covalent double bonding characters. The Pt=C bonds are much stronger than the C-H bond that may explain why the C atom CPt2H-/0 prefers to form Pt=C bonds rather than C-H bonds. It may also explain why platinum can insert into the C-H bond to activate the C-H bond as reported in the literature.

[Efficacy of Yu Si Granules on methyl methanesulphonate-induced oligoasthenozoospermia in mice].

OBJECTIVE: To investigate the effect and action mechanism of Yu Si Granules (YSG) in the treatment methyl methanesulphonate (MMS)-induced oligoasthenozoospermia (OAZ) in mice. METHODS: Thirty adult male mice were randomly divided into three groups of equal number, normal control, OAZ model control and YSG intervention. The OAZ model was established by oral administration of MMS and the model mice in the YSG intervention group were treated intragastrically with YSG suspension at 0.144 g/100 g of the body weight per day for 48 successive days. Then, all the mice were sacrificed and their epididymides harvested for detection of the sperm count and motility, observation of the morphology of the seminiferous tubules by HE staining, determination of the expressions of the germ cell-, sperm cell-, spermatocyte-, Sertoli cell- and blood-testis barrier-related genes by RT-PCR, and measurement of the levels of oxidative stress in the blood. RESULTS: Compared with the normal control, the OAZ model mice showed significantly decreased sperm count (ï¼»49.2 ± 0.7ï¼½ vs ï¼»23.6 ± 0.4ï¼½ ×107/ml/g, P < 0.05) and sperm motility (ï¼»76.3 ± 0.7ï¼½% vs ï¼»5.0 ± 5.8ï¼½%, P < 0.05), which were both remarkably increased after YSG intervention (ï¼»38.4 ± 0.5ï¼½ ×107/ml/g and ï¼»71.5 ± 0.5ï¼½%) (P < 0.05). The OAZ model mice also exhibited degenerated and atrophic seminiferous tubules, thinner seminiferous epithelia, disorderly arranged cells at different levels, reduced number of sperm in the lumen and unclear layers of germ cells in the epididymis, while those after YSG intervention manifested regularly organized seminiferous tubules with orderly arrangement and clear layers. The expressions of the Vasa, Dazl and Snd1 genes were significantly decreased (P < 0.05), but not those of Gfra, Plzf, Stra8, Spo11, Sycp3, Sox9 and Vim (P > 0.05) in the OAZ model and YSG intervention groups as compared with those in the normal control group. The superoxide dismutase (SOD) activity in the serum was markedly reduced in the OAZ model mice as compared with that in the normal controls (P < 0.05) and increased again after YSP intervention (P < 0.05), but the opposite was the case with the expression of the superoxide anion. CONCLUSIONS: YSG can significantly reduce MMS-induced OAZ in mice, which may be associated with oxidative stress.

Spin-Orbit Splittings and Low-Lying Electronic States of AuSi and AuGe: Anion Photoelectron Spectroscopy and ab Initio Calculations.

We measured the photoelectron spectra of diatomic AuSi- and AuGe- and conducted calculations on the structures and electronic properties of AuSi-/0 and AuGe-/0. The calculations at the CASSCF/CASPT2 level confirmed that experimentally observed spectra features of AuSi- and AuGe- can be attributed to the transitions from the 3Σ- anionic ground state to the 2Π (2Π1/2 and 2Π3/2), 4Σ-, 32Σ+, and 42Σ+ electronic states of their neutral counterparts. The electron affinities (EAs) of AuSi and AuGe are determined by the experiments to be 1.54 ± 0.05 and 1.51 ± 0.05 eV, respectively. The spin-orbit splittings (2Π1/2-2Π3/2) of AuSi and AuGe measured in this work are in agreement with the literature values. The energy difference between the 4Σ- (A) and 2Π1/2 states of AuSi obtained in this work is in reasonable agreement with the literature value, while that of AuGe obtained in this work by anion photoelectron spectroscopy is slightly larger than the literature value by neutral emission spectroscopy. The term energies of the 32Σ+ (B) and 42Σ+ (C) states of AuSi and AuGe were also determined based on the photoelectron spectra. Because of the different bond lengths between the anionic and neutral states, the electronic state terms energies of AuSi and AuGe estimated from the anion photoelectron spectra might be slightly different from those obtained from the neutral emission spectra.

Structural evolution and bonding properties of Au2Sin-/0 (n = 1-7) clusters: Anion photoelectron spectroscopy and theoretical calculations.

The photoelectron spectra of Au2Sin- (n = 1-7) clusters were measured, and the structural evolution and bonding properties of Au2Si1-7- anions and their corresponding neutral counterparts were investigated by theoretical calculations. The two Au atoms in Au2Si1-7-/0 prefer to occupy low coordinate sites and form fewer Au-Si bonds. The aurophilic interaction is fairly weak in these clusters. The most stable structures of both Au2Sin- anions and Au2Sin neutrals can be described as the two Au atoms interacting with the Sin frameworks. The most stable isomers of Au2Sin- anions are in spin doublet states, while those of the neutral clusters are in spin singlet states. The lowest-lying isomers of Au2Si1-/0 have C2v symmetric V-shaped structures. The global minimum of the Au2Si2- anion has a D2h symmetric planar rhombus structure, while that of the Au2Si2 neutral adopts a C2v symmetric dibridged structure. In Au2Si3-/0, the two Au atoms independently interact with the different Si-Si bonds of the Si3 triangular structure. The global minima of Au2Si4-7-/0 primarily adopt prismatic based geometries. Interestingly, Au2Si6-/0 have significant 3D aromaticity and possess σ plus π double bonding characters, which play important roles in their structural stability.

Structural evolution and bonding properties of BSi n - / 0 (n = 4-12) clusters: Size-selected anion photoelectron spectroscopy and theoretical calculations.

Size-selected anion photoelectron spectroscopy and theoretical calculations were used to investigate the structural evolution and bonding properties of BSin -/0 (n = 4-12) clusters. The results showed that the B atom in BSi4-12 -/0 prefers to occupy the high coordination sites to form more B-Si bonds. The lowest-lying isomers of BSi4-7 -/0 primarily adopt bowl-shaped based geometries, while those of BSi8-12 -/0 are mainly dominated by prismatic based geometries. For anionic clusters, BSi11 - is the critical size of the endohedral structure, whereas BSin neutrals form the B-endohedral structure at n = 9. Interestingly, both anionic and neutral BSi11 have a D 3h symmetric tricapped tetragonal antiprism structure with the B atom at the center and exhibit 3D aromaticity. The BSi11 - anion possesses σ plus π doubly delocalized bonding characters. The natural population analysis charge distributions on the B atom are related with the structural evolution of BSin - and the B-Si interactions.

Structures and electronic properties of B3Sin- (n = 4-10) clusters: A combined ab initio and experimental study.

The anionic silicon clusters doped with three boron atoms, B3Sin- (n = 4-10), have been generated by laser vaporization and investigated by anion photoelectron spectroscopy. The vertical detachment energies (VDEs) and adiabatic detachment energies (ADEs) of these anionic clusters are determined. The lowest energy structures of B3Sin- (n = 4-10) clusters are globally searched using genetic algorithm incorporated with density functional theory (DFT) calculations. The photoelectron spectra, VDEs, ADEs of these B3Sin- clusters (n = 4-10) are simulated using B3LYP/6-311+G(d) calculations. Satisfactory agreement is found between theory and experiment. Most of the lowest-energy structures of B3Sin- (n = 4-10) clusters can be derived by using the squashed pentagonal bipyramid structure of B3Si4- as the major building unit. Analyses of natural charge populations show that the boron atoms always possess negative charges, and that the electrons transfer from the 3s orbital of silicon and the 2s orbital of boron to the 2p orbital of boron. The calculated average binding energies, second-order differences of energies, and the HOMO-LUMO gaps show that B3Si6- and B3Si9- clusters have relatively high stability and enhanced chemical inertness. In particular, the B3Si9- cluster with high symmetry (C3v) stands out as an interesting superatom cluster with a magic number of 40 skeletal electrons and a closed-shell electronic configuration of 1S21P61D102S22P61F14 for superatom orbitals.