Machine Learning for Experimental Reactivity of a Set of Metal Clusters toward C-H Activation.

Understanding the mechanisms of C-H activation of alkanes is a very important research topic. The reactions of metal clusters with alkanes have been extensively studied to reveal the electronic features governing C-H activation, while the experimental cluster reactivity was qualitatively interpreted case by case in the literature. Herein, we prepared and mass-selected over 100 rhodium-based clusters (RhxVyOz- and RhxCoyOz-) to react with light alkanes, enabling the determination of reaction rate constants spanning six orders of magnitude. A satisfactory model being able to quantitatively describe the rate data in terms of multiple cluster electronic features (average electron occupancy of valence s orbitals, the minimum natural charge on the metal atom, cluster polarizability, and energy gap involved in the agostic interaction) has been constructed through a machine learning approach. This study demonstrates that the general mechanisms governing the very important process of C-H activation by diverse metal centers can be discovered by interpreting experimental data with artificial intelligence.

Spectroscopic Characterization of Thermal Methane Activation by Lewis-Acid-Base Pair in a Gas-Phase Metal Nitride Anion Ta2N3.

Activation and transformation of methane is one of the "holy grails" in catalysis. Understanding the nature of active sites and mechanistic details via spectroscopic characterization of the reactive sites and key intermediates is of great challenge but crucial for the development of novel strategies for methane transformation. Herein, by employing photoelectron velocity-map imaging (PEVMI) spectroscopy in conjunction with quantum chemistry calculations, the Lewis acid-base pair (LABP) of [Taδ+-Nδ-] unit in Ta2N3 - acting as an active center to accomplish the heterolytic cleavage of C-H bond in CH4 has been confirmed by direct characterization of the reactant ion Ta2N3 - and the CH4-adduct intermediate Ta2N3CH4 -. Two active vibrational modes for the reactant (Ta2N3 -) and four active vibrational modes for the intermediate (Ta2N3CH4 -) were observed from the vibrationally resolved PEVMI spectra, which unequivocally determined the structure of Ta2N3 - and Ta2N3CH4 -. Upon heating, the LABP intermediate (Ta2N3CH4 -) containing the NH and Ta-CH3 unit can undergo the processes of C-N coupling and dehydrogenation to form the product with an adsorbed HCN molecule.

Toward Designing Reactive Metal Clusters for Dinitrogen Activation: A Guideline Based on N2 Initial Adsorption.

Gas-phase metal clusters are ideal models to explore transition-metal-mediated N2 activation mechanism. However, the effective design and search of reactive clusters in N2 activation are currently hindered by the lack of clear guidelines. Inspired by the Sabatier principle, we discovered in this work that N2 initial adsorption energy (ΔEads) is an important parameter to control the N2 activation reactivity of metal clusters in the gas phase. This mechanistic insight obtained from high-level calculations rationalizes the N2 activation reactivity of many previously reported metal clusters when combined with the known factor determining the N≡N cleavage process. Furthermore, based on this guideline of ΔEads, we successfully designed several new reactive clusters for cleaving N≡N triple bond under mild conditions, including FeV2S2-, TaV2C2-, and TaV2C3-, the high N2 activation reactivity of which has been fully corroborated in our gas phase experiments employing mass spectrometry with collision-induced dissociation. The importance of ΔEads revealed in this work not only reshapes our understanding of N2 activation reactions in the gas phase but also could have implication for other N2 activation processes in the condensed phase. The more general establishment of this new perspective on N2 activation reactivity warrants future experimental and computational studies.

Magnetic covalent organic frameworks for extraction and determination of endocrine-disrupting chemicals in beverage and water samples.

BACKGROUND: Phenolic endocrine-disrupting chemicals (EDCs) are widespread and easily ingested through the food chain. They pose a serious threat to human health. Magnetic solid-phase extraction (MSPE) is an effective sample pre-treatment technology to determine traces of phenolic EDCs. RESULTS: Magnetic covalent organic framework (COF) (Fe3 O4 @COF) nanospheres were prepared and characterized. The efficient and selective extraction of phenolic EDCs relies on a large specific surface and the inherent porosity of COFs and hydrogen bonding, π-π, and hydrophobic interactions between COF shells and phenolic EDCs. Under optimal conditions, the proposed magnetic solid-phase extraction-high-performance liquid chromatography-ultra violet (MSPE-HPLC-UV) based on the metallic covalent organic framework method for phenolic EDCs shows good linearities (0.002-6 µg mL-1 ), with R2 of 0.995 or higher, and low limits of detection (6-1.200 ng mL-1 ). CONCLUSION: Magnetic covalent organic frameworks (Fe3 O4 @COFs) with good MSPE performance for phenolic EDCs were synthesized by the solvothermal method. The magnetic covalent organic framework-based MSPE-HPLC-UV method was applied successfully to determine phenolic EDCs in beverage and water samples with satisfactory recoveries (90.200%-123%) and relative standard deviations (2.100%-12.100%). © 2023 Society of Chemical Industry.

Selective Reduction of NO into N2 Catalyzed by Rh1-Doped Cluster Anions RhCe2O3-5.

Catalytic conversion of toxic nitrogen oxide (NO) and carbon monoxide (CO) into nitrogen (N2) and carbon dioxide (CO2) is imperative under the weight of the increasingly stringent emission regulations, while a fundamental understanding of the nature of the active site to selectively drive N2 generation is elusive. Herein, in combination with state-of-the-art mass-spectrometric experiments and quantum-chemical calculations, we demonstrated that the rhodium-cerium oxide clusters RhCe2O3-5- can catalytically drive NO reduction by CO and give rise to N2 and CO2. This finding represents a sharp improvement in cluster science where N2O is commonly produced in the rarely established examples of catalytic NO reduction mediated with gas-phase clusters. We demonstrated the importance of the unique chemical environment in the RhCe2O3- cluster to guide the substantially improved N2 selectivity: a triatomic Lewis "acid-base-acid" Ceδ+-Rhδ--Ceδ+ site is proposed to strongly adsorb two NO molecules as well as the N2O intermediate that is attached on the Rh atom and can facilely dissociate to form N2 assisted by both Ce atoms.

Dinitrogen Activation in the Gas Phase: Spectroscopic Characterization of C-N Coupling in the V3 C+ +N2 Reaction.

We report on cluster-mediated C-N bond formation in the gas phase using N2 as a nitrogen source. The V3 C+ +N2 reaction is studied by a combination of ion-trap mass spectrometry with infrared photodissociation (IRPD) spectroscopy and complemented by electronic structure calculations. The proposed reaction mechanism is spectroscopically validated by identifying the structures of the reactant and product ions. V3 C+ exhibits a pyramidal structure of C1 -symmetry. N2 activation is initiated by adsorption in an end-on fashion at a vanadium site, followed by spontaneous cleavage of the N≡N triple bond and subsequent C-N coupling. The IRPD spectrum of the metal nitride product [NV3 (C=N)]+ exhibits characteristic C=N double bond (1530 cm-1 ) and V-N single bond (770, 541 and 522 cm-1 ) stretching bands.

Superior Reactivity of Molybdenum-Sulfur Cluster Anions Mo5S2- and Mo5S3- toward Dinitrogen.

Inspired by the fact that Mo is a key element in biological nitrogenase, a series of gas-phase MoxSy- cluster anions are prepared and their reactivity toward N2 is investigated by the combination of mass spectrometry, photoelectron imaging spectroscopy, and density functional theory calculations. The Mo5S2- and Mo5S3- cluster anions show remarkable reactivity compared with the anionic species reported previously. The spectroscopic results in conjunction with theoretical analysis reveal that a facile cleavage of N≡N bonds takes place on Mo5S2- and Mo5S3-. The large dissociative adsorption energy of N2 and the favorable entrance channel for initial N2 approaching are proposed as two decisive factors for the superior reactivity of Mo5S2- and Mo5S3-. Besides, the modulation of S ligands on the reactivity of metal centers with N2 is proposed. The highly reactive metal-sulfur species may be obtained by the coordination of two to three sulfur atoms to bare metal clusters so that an appropriate combination of electronic structures and charge distributions can be achieved.

Using Normalized Carcinoembryonic Antigen and Carbohydrate Antigen 19 to Predict and Monitor the Efficacy of Neoadjuvant Chemotherapy in Locally Advanced Gastric Cancer.

Carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) are established prognostic biomarkers for patients with gastric cancer. However, their potential as predictive markers for neoadjuvant chemotherapy (NACT) efficacy has not been fully elucidated. METHODS: We conducted a retrospective analysis to determine values of CEA and CA19-9 prior to NACT (pre-NACT) and after NACT (post-NACT) in 399 patients with locally advanced gastric cancer (LAGC) who received intended NACT and surgery. RESULTS: Among the 399 patients who underwent NACT plus surgery, 132 patients (33.1%) had elevated pre-NACT CEA/CA19-9 values. Furthermore, either pre-NACT or post-NACT CEA /CA19-9 levels were significantly associated with prognosis (p = 0.0023) compared to patients with non-elevated levels. Moreover, among the patients, a significant proportion (73/132, 55.3%) achieved normalized CEA/CA19-9 following NACT, which is a strong marker of a favorable treatment response and survival benefits. In addition, the patients with normalized CEA/CA19-9 also had a prolonged survival compared to those who underwent surgery first (p = 0.0140), which may be attributed to the clearance of micro-metastatic foci. Additionally, the magnitude of CEA/CA19-9 changes did not exhibit a statistically significant prognostic value. CONCLUSIONS: Normalization of CEA/CA19-9 is a strong biomarker for the effectiveness of treatment, and can thus be exploited to prolong the long-term survival of patients with LAGC.

A liquid biopsy signature of circulating exosome-derived mRNAs, miRNAs and lncRNAs predict therapeutic efficacy to neoadjuvant chemotherapy in patients with advanced gastric cancer.

At present, there is no validated marker to identify the subpopulation of patients with advanced gastric cancer (AGC) who might benefit from neoadjuvant chemotherapy (NACT). In view of this clinical challenge, the identification of non-invasive biomarkers for efficacy prediction of NACT in patients with AGC is imperative. Herein, we aimed to develop a non-invasive, liquid-biopsy-based assay by using an exosome-derived RNAs model based on multi-omics characteristics of RNAs. We firstly used a multi-omics strategy to characterize the mRNAs, microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) profiles of circulating exosome enriched fractions in responders to NACT paired with non-responders, using RNA sequencing. Finally, numerous miRNAs, mRNAs and lncRNAs were identified to be associated with the response to NACT in patients with AGC, and it was validated in an independent cohort with promising AUC values. Furthermore, we established a 6-exosome-RNA panel that could robustly identified responders from non-responders treated with fluorouracil-based neoadjuvant chemotherapy.

A comparative study on the reactivity of ditantalum deuteride cluster anions Ta2D2- and Ta2D4- toward N2.

The activation and transformation of molecular nitrogen (N2) by metal hydride species has attracted widespread attention due to its critical role in nitrogen fixation. Herein, the reactions between tantalum deuteride cluster anions Ta2D2,4- and N2 were investigated experimentally and theoretically. An unprecedented reaction channel of the liberation of a single D atom was observed and much superior reactivity was identified for Ta2D4-. Theoretical investigations indicate that the releasing of D atoms benefits from the completely dissociative adsorption of N2 on the dinuclear metal centres. The extra D atoms in Ta2D4- compared to Ta2D2- are helpful to create sufficient electron density at the adsorption site and modify the symmetry of active orbitals to facilitate a further reduction of N2. This comparative study provides a molecular-level insight to understand the high structure-modulating capability of the additional hydride ligands in polyhydride species in the adsorption and activation of nitrogen molecules.

Reverse water-gas shift reaction catalyzed by diatomic rhodium anions.

The reverse water-gas shift (RWGS, CO2 + H2 → CO + H2O, ΔH298 = +0.44 eV) reaction mediated by the diatomic anion Rh2- was successfully constructed. The generation of a gas-phase H2O molecule and ion product [Rh2(CO)ads]- was identified unambiguously at room temperature and the only elementary step that requires extra energy to complete the catalysis is the desorption of CO from [Rh2(CO)ads]-. This experimentally identified Rh2- anion represents the first gas-phase species that can drive the RWGS reaction because it is challenging to design effective routes to yield H2O from CO2 and H2. The reactions were performed by using our newly developed double ion trap reactors and characterized by mass spectrometry, photoelectron spectroscopy, and high-level quantum-chemical calculations. We found that the order that the reactants (CO2 or D2) were fed into the reactor did not have a pronounced impact on the reactivity and the final product distribution (D2O and Rh2CO-). The atomically precise insights into the key steps to guide the reaction toward the RWGS direction were provided.

Lithium-Assisted Dinitrogen Reduction Mediated by Nb2LiNO1-4- Cluster Anions: Electron Donors or Structural Units.

Alkali atoms are usually used as promoters to significantly increase the catalytic activity of transition-metal catalysts in a wide range of reactions such as dinitrogen conversion reactions. However, the role of alkali metal atoms remains controversial. Herein, a series of quaternary cluster anions containing lithium atoms Nb2LiNO1-4- have been synthesized and reacted with N2 at room temperature. The detailed experimental and theoretical investigations indicate that Nb2LiNO- is capable to cleave the N≡N bond and the Li atoms in Nb2LiNO1,2- act as electron donors in the N2 reduction reaction. With the increase in the number of oxygen atoms, the reactivity toward N2 is reduced from adsorption via a side-on end-on mode in Nb2LiNO2- to the inertness of Nb2LiNO4-. In Nb2LiNO3,4- anions, the Li atoms are bonded with oxygen atoms, acting as structural units to stabilize structures. Therefore, the roles of alkali atoms are able to change with different chemical environments of active sites. For the first time, we reveal how the number of ligands (oxygen atoms herein) can be used to finely regulate the reactivity toward N2.

Size-dependent reactivity of rhodium deuteride cluster anions Rh3Dn - (n = 0-3) toward dinitrogen: The prominent role of σ donation.

Nitrogen (N2) fixation is a challenging task for chemists. Adsorption of N2 on transition metal (TM) sites has been identified as a prerequisite for activating the very stable N≡N triple bond in both industrial and biological processes. The importance of π back-donation (filled orbitals of TM → π* orbitals of N2) between metal sites and N2 has been well elucidated while the role of another classic orbital interaction, namely σ donation (σ orbitals of N2 → empty orbitals of TM), remains ambiguous. Herein, the size-dependent reactivity of trinuclear rhodium deuteride cluster anions Rh3Dn - (n = 0-3) toward N2 adsorption in the gas phase was investigated experimentally and theoretically. A reverse relationship that higher electron-donating ability of clusters corresponds to lower N2 adsorption reactivity was experimentally observed, which is uncommon in N2 activation by gas-phase species. Theoretical analysis revealed that the σ donation rather than the π back-donation plays a predominant role in the adsorption complexes Rh3DnN2 - and the enhanced reactivity upon D addition is ascribed to the lowered energy levels of active orbitals in Rh3Dn - as n increases. This study provides the first experimental evidence to declare the important role of σ donation and new clues for the design of reactive metal species in nitrogen fixation.

Dinitrogen Activation by Heteronuclear Metal Carbide Cluster Anions FeTaC2-: A 5d Early and 3d Late Transition Metal Strategy.

Cleavage of the strong N≡N bond has long been a great challenge for energy-efficient dinitrogen (N2) fixation; thus a reasonable design of reactive species to activate N2 under mild conditions is highly desirable and meaningful. Herein a novel N2 activation strategy of combining 5d early (E) and 3d late (L) transition metals (TMs) is proposed, which is verified by the facile and complete N≡N cleavage via the polarized Fe-Ta bond in gas-phase cluster FeTaC2-. The efficient N≡N cleavage benefits from an electronic-level design of highly strengthened donor-acceptor interactions, in which the 5d-ETM (Ta) mainly pushes electrons from occupied 5d-orbitals to N2 π*-orbitals while the 3d-LTM (Fe) simultaneously pulls electrons from N2 σ/π-orbitals to its unoccupied 3d-orbitals. Through employing 5d-ETM and 3d-LTM to play their respective roles, this work provides a new and versatile idea for activating the inert N≡N bond and inspires relevant design of TM-based catalysts.

Exosome-derived noncoding RNAs in gastric cancer: functions and clinical applications.

Exosomes are a subpopulation of the tumour microenvironment (TME) that transmit various biological molecules to promote intercellular communication. Exosomes are derived from nearly all types of cells and exist in all body fluids. Noncoding RNAs (ncRNAs) are among the most abundant contents in exosomes, and some ncRNAs with biological functions are specifically packaged into exosomes. Recent studies have revealed that exosome-derived ncRNAs play crucial roles in the tumorigenesis, progression and drug resistance of gastric cancer (GC). In addition, regulating the expression levels of exosomal ncRNAs can promote or suppress GC progression. Moreover, the membrane structures of exosomes protect ncRNAs from degradation by enzymes and other chemical substances, significantly increasing the stability of exosomal ncRNAs. Specific hallmarks within exosomes that can be used for exosome identification, and specific contents can be used to determine their origin. Therefore, exosomal ncRNAs are suitable for use as diagnostic and prognostic biomarkers or therapeutic targets. Regulating the biogenesis of exosomes and the expression levels of exosomal ncRNAs may represent a new way to block or eradicate GC. In this review, we summarized the origins and characteristics of exosomes and analysed the association between exosomal ncRNAs and GC development.

Reappraise role of No. 10 lymphadenectomy for proximal gastric cancer in the era of minimal invasive surgery during total gastrectomy: a pooled analysis of 4 prospective trial.

BACKGROUND: For patients with locally advanced proximal gastric cancer (LAPGC), the individualized selection of patients with highly suspected splenic hilar (No. 10) lymph node (LN) metastasis to undergo splenic hilar lymphadenectomy, is a clinical dilemma. This study aimed to re-evaluate the feasibility and safety of laparoscopic spleen-preserving splenic hilar lymphadenectomy (LSPSHL) and to identify the population who would benefit from it. METHODS: A total of 1068 patients (D2 group = 409; D2 + No. 10 group = 659) who underwent laparoscopic total gastrectomy from four prospective trials between January 2015 and July 2019 were analyzed. RESULTS: No significant difference in the incidence (16.9% vs. 16.4%; P = 0.837) of postoperative complications were found between the two groups. The metastasis rate of No. 10 LN among patients in the D2 + No. 10 group was 10.3% (68/659). Based on the decision tree, patients with LAPGC with tumor invading the greater curvature (Gre), patients with non-Gre-invading LAPGC with a tumor size > 5 cm and clinical positive locoregional LNs were defined as the high-priority No. 10 dissection group. The metastasis rate of No. 10 LNs in the high-priority group was 19.4% (41/211). In high-priority group, the 3-year overall survival of the D2 + No. 10 group was better than that of the D2 group (74.4% vs. 42.1%; P = 0.005), and the therapeutic index of No. 10 was higher than the indices of most suprapancreatic stations. CONCLUSIONS: LSPSHL for LAPGC is safe and feasible when performed by experienced surgeons. LSPSHL could be recommended for the high-priority group patients even without invasion of the Gre.

EM-2 inhibited autophagy and promoted G2/M phase arrest and apoptosis by activating the JNK pathway in hepatocellular carcinoma cells.

This study aimed to investigate the inhibitory effect of EM-2, a natural active monomer purified from Elephantopusmollis H.B.K., on the proliferation of human hepatocellular carcinoma cells and the molecular mechanism involved. The results from the MTT assay revealed that EM-2 significantly inhibited the proliferation of human hepatocellular carcinoma (HCC) cells in a dose-dependent manner but exhibited less cytotoxicity to the normal liver epithelial cell line LO2. EdU staining and colony formation assays further confirmed the inhibitory effect of EM-2 on the proliferation of Huh-7 hepatocellular carcinoma cells. According to the RNA sequencing and KEGG enrichment analysis results, EM-2 markedly activated the MAPK pathway in Huh-7 cells, and the results of Western blotting further indicated that EM-2 could activate the ERK and JNK pathways. Meanwhile, EM-2 induced apoptosis in a dose-dependent manner and G2/M phase arrest in Huh-7 cells, which could be partially reversed when treated with SP600125, a JNK inhibitor. Further study indicated that EM-2 induced endoplasmic reticulum stress and blocked autophagic flux in Huh-7 cells by inhibiting autophagy-induced lysosome maturation. Inhibition of autophagy by bafilomycin A1 could reduce cell viability and increase the sensitivity of Huh-7 cells to EM-2. In conclusion, our findings revealed that EM-2 not only promoted G2/M phase arrest and activated ER stress but also induced apoptosis by activating the JNK pathway and blocked autophagic flux by inhibiting autolysosome maturation in Huh-7 hepatocellular carcinoma cells. Therefore, EM-2 is a potential therapeutic drug with promising antitumor effects against hepatocellular carcinoma and fewer side effects.

A Facile N≡N Bond Cleavage by the Trinuclear Metal Center in Vanadium Carbide Cluster Anions V3C4.

Cleavage of the triple N≡N bond by metal clusters is of fundamental interest and practical importance in nitrogen fixation. Previous studies of N≡N bond cleavage by gas-phase metal clusters emphasized the importance of the dinuclear metal centers. Herein, the dissociative adsorption of N2 and subsequent C-N coupling on trinuclear carbide cluster anions V3C4- under thermal collision conditions have been characterized by employing mass spectrometry (collision induced dissociation), cryogenic photoelectron imaging spectroscopy, and quantum chemistry calculations. A theoretical analysis identified a crucial adsorption intermediate with N2 bonded with the V3 metal core in the end-on/side-on/side-on (ESS) mode, which most likely enables the facile cleavage of the N≡N bond. Such a vital N2 coordination in the ESS mode is a result of symmetry-matched interactions between the occupied orbitals of the metal core and both of the two empty π* orbitals of N2. Furthermore, carbon ligands also play a considerable role in enhancing the reactivity of the metal core toward N2. This study strongly suggests a new mechanism of N≡N bond cleavage by gas-phase metal clusters.

Four-Point Computed Tomography Scores for Evaluation of Occult Peritoneal Metastasis in Patients with Gastric Cancer: A Region-to-Region Comparison with Staging Laparoscopy.

BACKGROUND: Preoperative diagnosis of peritoneal metastasis with gastric cancer remains challenging. This study explored the abnormal computed tomography (CT) signs of occult peritoneal metastasis (OPM) and evaluated it by region-to-region comparison using staging laparoscopy, from which a 4-point CT score system was developed. METHODS: Patients with advanced gastric cancer (stage cT ≥ 2M0) diagnosed by CT were enrolled in the study. Occult peritoneal metastasis detected during staging laparoscopy was compared with preoperative CT to investigate the presence of abnormal signs by a region-to-region comparison. A 4-point CT score system was developed to define the radiologic characteristics. Subsequently, the diagnostic efficacy of the CT score system was prospectively verified. RESULTS: In this study, 57 OPM regions were detected by staging laparoscopy in 33 of the 385 enrolled patients. The greater omentum was the most frequent site of OPM (38.60%, 22/57), which usually exhibited a smudge-like ground-glass opacity (S-GGO) (90.91%, 20/22) with a mean CT score of 2.14. The parietal and perihepatic peritoneum was the second most common site (22.81%, 13/57). A 4-point CT score system was developed based on the results. A cutoff CT score of 2 or higher was associated with a false-negative rate of 2% (2/99). This CT score system had a sensitivity of 87.5% and a specificity of 76.4% for an OPM-positive diagnosis (area under the curve, 0.848). The agreement between two radiologists on the assigned final score was 76.2% (kappa, 0.5). CONCLUSIONS: Patients with OPM mostly exhibited S-GGO on CT, which should be interpreted cautiously. The 4-point CT score system may improve the pretreatment evaluation of occult peritoneal metastasis, and staging laparoscopy might not be necessary for patients with a score lower than 2.

Reactivity of Neutral Tantalum Sulfide Clusters Ta3Sn (n = 0-4) with N2.

Nitrogen (N2) fixation is a challenging and vital issue in chemistry. Inspired by the fact that the active sites of nitrogenases are polynuclear metal sulfide clusters, the reactivity of gas-phase metal sulfide clusters toward N2 has received considerable attention to gain fundamental insights into nitrogen fixation. Herein, neutral tantalum sulfide clusters have been prepared and their reactivity toward N2 has been investigated by mass spectrometry in conjunction with density functional theory (DFT) calculations. The experimental results showed that Ta3Sn (n = 0-3) could adsorb N2, while Ta3S4 was inert to N2. The DFT calculations revealed that the complete cleavage of the N≡N bond on the trinuclear metal center in the Ta3S0-3/N2 reaction systems was overall barrierless under thermal collision conditions. The sulfur ligands can facilitate the approaching of N2 toward the metal center but weaken the electron-donating ability of the metal center. The inertness of Ta3S4 is ascribed to the electron-deficient state of Ta3 in Ta3S4 and the least effective orbital interaction in the Ta3S4/N2 couple. This study provides new insights into the ligand effect on the interaction of the metal clusters with N2.