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Mass spectrometry was used to observe the reactions between Y−Co heteronuclear metal carbide cluster anions Y1‐3CoC1,2− and N2 at room temperature. Y2CoC1,2− can produce Co ejection products, in which Y2CoC− also has N2 association products; YCoC2− and Y3CoC− only generate N2 association products, while YCoC− and Y3CoC2− are inert to N2. Detailed reaction pathways were obtained through density functional theory calculations, which reasonably explain the experimental phenomena. Co is superior to Y as the electrophilic reaction site in the clusters and is the preferential initial adsorption site for N2. Some crucial steps were identified, including N−N dissociation, CC−N formation, C−CN dissociation, and C−N formation. The energy barriers of these steps are closely related to the coordination mode of N/N2 and C/C2 in clusters. Two indicators, the N−N bond length and the Mayer bond order, were utilized to describe the activation degree of the N−N bond. Analyses on the density of states and the frontier molecular orbitals reveal the electronic structures of key intermediates for N−N dissociation. The reaction mechanisms of N2 activation on Y−Co carbide clusters obtained may lay a preliminary foundation for the further development of catalysts for nitrogen reduction reaction (NRR). [ABSTRACT FROM AUTHOR]

N2 adsorption is a prerequisite for activation and transformation. Time-of-flight mass spectrometry experiments show that the Nb2C6H4+ cation, resulting from the gas-phase reaction of Nb2+ with C6H6, is more favorable for N2 adsorption than Nb+ and Nb2+ cations. Density functional theory calculations reveal the effect of the ortho-C6H4 ligand on N2 adsorption. In Nb2C6H4+, interactions between the Nb-4d and C-2p orbitals enable the Nb2+ cation to form coordination bonds with the ortho-C6H4 ligand. Although the ortho-C6H4 ligand in Nb2C6H4+ is not directly involved in the reaction, its presence increases the polarity of the cluster and brings the highest occupied molecular orbital (HOMO) closer to the lowest occupied molecular orbital (LUMO) of N2, thereby increasing the N2 adsorption energy, which effectively facilitates N2 adsorption and activation. This study provides fundamental insights into the mechanisms of N2 adsorption in "transition metal–organic ligand" systems. [ABSTRACT FROM AUTHOR]

The activation and hydrogenation of nitrogen are central in industry and in nature. Through a combination of mass spectrometry and quantum chemical calculations, this work reports an interesting result that scandium nitride cations Sc3N+ can activate sequentially H2 and N2, and an amido unit (NH2) is formed based on density functional theory calculations, which is one of the inevitable intermediates in the N2 reduction reactions. If the activation step is reversed, i.e., sequential activation of first N2 and then H2, the reactivity decreases dramatically. An association mechanism, prevalent in some homogeneous catalysis and enzymatic mechanisms, is adopted in these gas-phase H2 and N2 activation reactions mediated by Sc3N+ cations. The mechanistic insights are important to understand the mechanism of the conversion of H2 and N2 to NH3 synthesis under ambient conditions. [ABSTRACT FROM AUTHOR]

Gas-phase vanadium oxide cluster cations and anions are prepared by laser ablation. The small cluster ions (<1000 amu) are mass-selected using a quadrupole mass filter and reacted with benzene in a linear ion trap reactor; large clusters (>1000 amu) with no mass selection are reacted with C6H6 in a fast flow reactor. Rich product variety is encountered in these reactions, and the reaction channels for small cationic and anionic systems are different. For large clusters, the reactivity patterns of (V2O5)n+ (n = 6-25) and (V2O5)nO− (n = 6-24) cluster series are very similar to each other, indicating that the charge state has little influence on the oxidation of benzene. In sharp contrast to the dramatic changes of reactivity of small clusters, a weakly size dependent reaction behavior of large (V2O5)6-25+ and (V2O5)6-24O− clusters is observed. Therefore, the charge state and the size are not the major factors influencing the reactivity of nanosized vanadium oxide cluster ions toward C6H6, which is not common in cluster science. In the reactions with benzene, the small and large reactive vanadium oxide cations show similar reactivity of hydroxyl radicals (OH•) toward C6H6 at higher and lower temperatures, respectively; different numbers of vibrational degrees of freedom and the released energy during the formation of adduct complexes can explain this intriguing correlation. The reactions investigated herein might be used as the models of how to realize the partial oxidation of benzene to phenol in a single step, and the observed mechanisms are helpful to understand the corresponding heterogeneous reactions, such as those over vanadium oxide aerosols and vanadium oxide catalysts. [ABSTRACT FROM AUTHOR]

Transition‐metal catalyzed coupling to form C−N bonds is significant in chemical science. However, the inert nature of N2 and CO2 renders their coupling quite challenging. Herein, we report the activation of dinitrogen in the mild plasma atmosphere by the gas‐phase monometallic YB1–4− anions and further coupling of CO2 to form C−N bonds by using mass spectrometry and theoretical calculation. The observed product anions are NCNBO− and N(BO)2−, accompanied by the formation of neutral products YO and YB0–2NC, respectively. We can tune the reactivity and the type of products by manipulating the number of B atoms. The B atoms in YB1–4N2− act as electron donors in CO2 reduction reactions, and the carbon atom originating from CO2 serves as an electron reservoir. This is the first example of gas‐phase monometallic anions, which are capable to realize the functionalization of N2 with CO2 through C−N bond formation and N−N and C−O bond cleavage. [ABSTRACT FROM AUTHOR]

The adsorption of atmospheric dinitrogen (N2) on transition metal sites is an important topic in chemistry, which is regarded as the prerequisite for the activation of robust N≡N bonds in biological and industrial fields. Metal hydride bonds play an important part in the adsorption of N2, while the role of hydrogen has not been comprehensively studied. Herein, we report the N2 adsorption on the well-defined Y2C4H0,1− cluster anions under mild conditions by using mass spectrometry and density functional theory calculations. The mass spectrometry results reveal that the reactivity of N2 adsorption on Y2C4H− is 50 times higher than that on Y2C4− clusters. Further analysis reveals the important role of the H atom: (1) the presence of the H atom modifies the charge distribution of the Y2C4H− anion; (2) the approach of N2 to Y2C4H− is more favorable kinetically compared to that to Y2C4−; and (3) a natural charge analysis shows that two Y atoms and one Y atom are the major electron donors in the Y2C4− and Y2C4H− anion clusters, respectively. This work provides new clues to the rational design of TM-based catalysts by efficiently doping hydrogen atoms to modulate the reactivity towards N2. [ABSTRACT FROM AUTHOR]

The activation and functionalization of dinitrogen with carbon dioxide into useful chemicals containing C–N bonds are significant research projects but highly challenging. Herein, we report that N2 molecules are dissociated by heterobimetallic CuNb− anions assisted by surface plasma radiation, leading to the formation of CuNbN2− anions; the CuNbN2− anions can further react with CO2 to generate products NCO− with one C–N bond and NbO2NCN− with two C–N bonds under thermal collision conditions. For the activation of dinitrogen, the plasma atmosphere is conducive to the dissociation of the N≡N bond, which renders the coupling reactions of N2 and CO2 molecules easier to proceed. This is the first report of coupling of N2 and CO2 to generate C–N bonds by making good use of the plasma effect to assist in the activation of N2 molecules. This new strategy with the assistance of plasma provides a practicable route to construct C–N bonds by directly using N2 and CO2 at room temperature. [ABSTRACT FROM AUTHOR]

The activation of carbon dioxide (CO2) mediated by NbBN2− cluster anions under the conditions of thermal collision has been investigated by time-of-flight mass spectrometry combined with density functional theory calculations. Two C＝O double bonds in the CO2 molecule are completely broken and two C–N bonds are further generated to form the novel molecule NCNBO−. To the best of our knowledge, this new molecule is synthesized and reported for the first time. In addition, one oxygen atom transfer channel produces another product, NbBN2O−. Both of the Nb and B atoms in NbBN2− donate electrons to reduce CO2, and the carbon atom originating from CO2 serves as an electron reservoir. The reaction of NbB− with N2 was also investigated theoretically, and the formation of NbBN2− from this reaction is thermodynamically and kinetically quite favorable, indicating that NCNBO− might be produced from the coupling of N2 and CO2 mediated by NbB− anions. [ABSTRACT FROM AUTHOR]

Cleavage of all C–H bonds in two methane molecules by gas-phase cluster ions at room temperature is a challenging task. Herein, mass spectrometry and quantum chemical calculations have been used to identify one single metal boride cluster anions NbB4− that can activate eight C–H bonds in two methane molecules and release one H2 molecule each time under thermal collision conditions. In these consecutive reactions, the loaded Nb atoms and the support B4 units play different roles but act synergistically to activate CH4, which is responsible for the interesting reactivity of NbB4−. Moreover, there are some mechanistic differences in these two reactions, including the mechanisms for the first C–H bond activation steps, dihydrogen desorption sites, and major electron donors. This study shows that non-noble metal boride species are reactive enough to facilitate thermal C–H bond cleavages, and boron-based materials may be one kind of potential support material facilitating surface hydrogen transport. [ABSTRACT FROM AUTHOR]

The thermal gas-phase reactions of Nb2BN2− cluster anions with carbon dioxide have been explored by using the art of time-of-flight mass spectrometry and density functional theory calculations. Four CO2 molecules can be consecutively reduced by Nb2BN2−, resulting in the formation of Nb2BN2O1–4− anions and the release of one CO molecule each time. To illustrate the role of ligands in Nb2BN2−, the reactivities of Nb2N2− and Nb2B− toward CO2 were also investigated; two and three CO2 molecules are activated, respectively, and the rate constants are slower than that of Nb2BN2−/CO2 systems. This comparison indicates that metal–metal multiple bonds and appropriate ligands, such as B, are important factors for CO2 reduction. The synergy between a transition metal atom (Nb) and a main-group atom (B) in CO2 reduction mediated by gas-phase clusters is revealed for the first time. To the best of our knowledge, Nb2BN2− anions are gas-phase clusters that reduce the largest number of CO2 molecules. A fundamental understanding of the efficient reduction of carbon dioxide molecules may shed light on the rational design of active sites on supported transition metal/boron nitride catalysts. [ABSTRACT FROM AUTHOR]