Non‐Dissociative Activation of Chemisorbed Dinitrogen on One or Two Vanadium Atoms Supported by a Mo₆S₈ Cluster

Abstract

Adsorption of N2 on Mo6S8q_Vx clusters (x=0, 1, 2; q=0, ±1) were systematically studied by density functional theory calculations with dispersion corrections. It was found that the N2 can be chemisorbed and undergo non‐dissociative activation on single or double metal atoms. The adsorption and activation are influenced by metal types (V or Mo), N2 coordination modes and charge states of the clusters. Particularly, anionic Mo6S8−_V2 clusters have remarkable ability to fix and activate N2. In Mo6S8−_V2, two V atoms prefer to adsorb on two adjacent S−Mo−S hollow sites, leading to the formation of a supported V…V unit. The N2 is bridged side‐on coordinated with these two V atoms with high adsorption energy and significant charge transfer. The bond order, bond length and vibration frequency of the adsorbed N2 are close to those of a N−N single bond.

Facile N≡N Bond Cleavage by Anionic Trimetallic Clusters V3−xTaxC4− (x=0–3): A DFT Study

“…According to this definition, when the system loses electrons, the electrons will mainly come from the area with larger f − values. Considering that N 2 adsorption needs to get electrons from the clusters (i. e., an electrophilic reaction), [19j] sites with larger f − are more favored for N 2 adsorption. As seen in Figure 2, the isosurface near Site 1 is more significant than those near Sites 2 and 3, which shows that the possibility of electrophilic reaction at Site 1 is higher than that at Sites 2 and 3.…”

“…Gas‐phase clusters with a determined number of metal atoms can be prepared conveniently in experiments, and detailed reaction mechanisms can be obtained by combining with theoretical investigations [18] . So far, the reaction of metal‐containing clusters with N 2 has been widely studied, [17d,e,19] such as pure metal clusters (e. g., Ta 2 +[17d] and Ru 8 +[19c] ), metal carbides (Ta 2 C 4 −[19f] and FeTaC 2 −[19n] ), hydrides (NbH 2 −[19g] ), nitrides (V 5 N 5 −[19i] ), and sulfides (V 1,2 Mo 6 S 8 , [19j] Fe 5 S 2 − and Fe 5 S 3 −[19o] ), while only a few studies are on homonuclear trimetallic clusters, such as V 3 C 4 − , [12b] Co 3 D n − , [20] Sc 3 N + , [21] Ta 3 S n , [22] and Ta 3 N 3 H 0,1 − [23] . The ESS coordination mode of N 2 on three metal atoms was found in most of these trimetallic clusters and the electronic structures of reaction intermediates were obtained, indicating that cluster models are effective to reveal the mechanisms of N 2 reactions from a molecular level.…”

“…FBO analysis is adopted since it has small basis set sensitivity and is suitable for calculations with diffuse functions [28] . Our previous work on N 2 activation [19j] also indicated that FBO can provide proper values of N−N bonds in agreement with the classical chemical notions. All energies reported are with ZPE correction unless specified.…”

Experimental and Theoretical Study of N2 Adsorption on Hydrogenated Y2C4H− and Dehydrogenated Y2C4− Cluster Anions at Room Temperature

“…Scientists regularly rely on transition metal (TM) centers to catalyze the nitrogen conversion processes [5][6][7]. The initial and critical step in the complicated reduction of dinitrogen is the adsorption of N 2 molecules at the TM center [8,9]. The fixation of nitrogen in industry is carried out at metal-based (Fe − or Ru − ) catalysts under extremely high temperatures (300-500 • C) and high pressures (100-300 atm), involving the disadvantages of large energy consumption and greenhouse gas emission [10][11][12].…”

Nitrogen Activation and Transformation on Monometallic Niobium Boron Oxide Cluster Anions at Room Temperature: A Dual-Site Mechanism

“…The combined use of experimental and theoretical techniques is a powerful methodology for the investigation of model reactions between N 2 and gas-phase species and has been used to reveal N 2 activation mechanisms in an unperturbed environment at a strictly molecular level. − Specifically, the gas-phase species ,,,− that possess the ability to cleave the NN triple bond under thermal collision conditions commonly involve the cooperation of more than one TM atom, for adsorbing and activating N 2 , with the exception of the previously reported Os/N 2 system . It is noteworthy that, although there are increasing reports on the N 2 activation mediated by gas-phase ions, the transformation of N 2 has rarely been reported. , Considering that the empty p orbital in boron is similar to the d orbital of transition metals and can, therefore, participate in efficient “donor–acceptor” processes upon interaction with N 2 , several B-based catalysts have been reported to be able to activate N 2 . − Thus, boron-doped clusters probably are promising systems exhibiting a high reactivity toward N 2 activation.…”