The performance of DMSO for the dehydration of fructose to 5-hydroxymethylfurfural (HMF) in the presence and absence of Brønsted acid has been theoretically investigated at G4 level in DMSO solution. The most stable form of fructose is β-D-fructofuranoses in DMSO solution. When Brønsted acid is present in the reaction system, H+ prefers to interact with DMSO other than fructose, forming [DMSOH]+ as the catalytically active species. For the dehydration of fructose to HMF, the catalytic performance of DMSO stems from the valence unsaturation of both S and O atoms and the unsaturated double bond of S═O, and the catalytic role of [DMSOH]+ originates from the valence unsaturation of both S and O atoms, as well as the H-mediated effect of −SOH group. For the initial and third water molecule release steps from fructose, both DMSO and [DMSOH]+ exhibit catalytic activity. Nevertheless, for the second water molecule release step from fructose, [DMSOH]+ displays catalytic activity, but DMSO does not. The active species [DMSOH]+ exhibits better catalytic performance than DMSO. The turnover frequency analysis shows that an intermolecular hydride transfer between DMSO or [DMSOH]+ moiety and fructose moiety is the rate-controlling step, which is associated with the C–H bond cleavage of the −CH2OH group of fructose moiety. The present study brings some insight into the role of DMSO for the acid-catalyzed dehydration of carbohydrates to HMF in DMSO solution.Keywords: 5-hydroxymethylfurfural; Brønsted acid; dimethyl sulfoxide; fructose; G4;

Little is known about the detailed structural information at the interface of Ptn cluster and γ-Al2O3(001) surface, which plays an important role in the dehydrogenation and cracking of hydrocarbons. Here, the nucleation and growth of Ptn (n = 1–8, 13) clusters on a γ-Al2O3(001) surface have been examined using density functional theory. For the most stable configuration Ptn/γ-Al2O3(001) (n = 1–8, 13), Ptn clusters bond to the γ-Al2O3(001) surface through Pt–O and Pt–Al bonds at the expense of electron density of the Ptn cluster. With the increase in the Ptn cluster size, both the metal–support interaction and the nucleation energies exhibit an odd–even oscillation pattern, which are lower for an even Ptn cluster size than those for its adjacent odd ones. Both the metal–surface and metal–metal interactions are competitive, which control the nanoparticle morphology transition from two-dimension (2D) to three-dimension (3D). On the γ-Al2O3(001) surface, when the metal–support interaction governs, smaller clusters such as Pt1, Pt2, Pt3, and Pt4 prefer a planar 2D nature. Alternatively, when the metal–metal interaction dominates, larger clusters such as Pt5, Pt6, Pt7, Pt8, and Pt13 exhibit a two-layer structure with one or more Pt atoms on the top layer not interacting directly with the support. Herein, the Pt4 cluster is the most stable 2D structure; Pt5 and Pt6 clusters are the transition from the 2D to the 3D structure; and the Pt7 cluster is the smallest 3D structure.Topics: Adsorption; Catalysts; Electron transfer; Electronic structure; Energy; Energy level; Metal clusters; Molecular structure; Phase transition; Potential energy; Surface structure; Thermodynamic properties;

•Ethanol does not show any catalytic activity toward the fructose dehydration.•Proton H+ is solvated on ethanol, resulting in [C2H5OH2]+ as the active species.•[C2H5OH2]+ exhibits better catalytic performance than the proton H+.•[C2H5OH2]+ shifts the intramolecular H-shift to the intermolecular H-shift.•Ethanol promotes the H+ catalytic effect toward the fructose dehydration.The function of ethanol and Brønsted acid for the dehydration-etherification of fructose to 5-ethoxymethylfurfural (EMF) has been theoretically investigated at G4 level in ethanol solution. Initially, fructose prefers to dehydration other than etherification with ethanol in the presence of Brønsted acid. The proton H+ should be solvated on ethanol other than fructose, resulting in [C2H5OH2]+ as the catalytically active species. Both protonation and [C2H5OH2]+ exhibit good catalytic performance, but ethanol does not. Furthermore, [C2H5OH2]+ displays better catalytic performance than protonation, which reflects the promotion catalytic role of C2H5OH on the proton H+. The turnover frequency analysis shows that the SN2 nucleophilic substitution for the etherification of 5-hydroxymethylfurfural (HMF) to EMF is the rate-controlling step in the whole reaction catalyzed by [C2H5OH2]+. The catalytic performance of [C2H5OH2]+ stems from the positive charge of OH2 group, which assists both the H2O release of fructose to HMF and the etherification of HMF to EMF. For the dehydration of fructose, the catalytic superiority of [C2H5OH2]+ to protonation comes from the shift of the intramolecular H-shift catalyzed by protonation to the intermolecular H-shift catalyzed by [C2H5OH2]+, which lowers the activation energy barrier for the H2O release. The present study is useful for understanding the roles of ethanol and Brønsted acid in acid-catalyzed dehydration-etherification of carbohydrates to biofuel in ethanol solution.Download high-res image (67KB)Download full-size image

The formation mechanism of CdSe monomers from the reaction of cadmium oleate (Cd(OA)2) and SePPh2H in the presence of HPPh2 and RNH2 was studied systematically at the M06//B3LYP/6-31++G(d,p),SDD level in 1-octadecene solution. Herein, SePPh2H, HPPh2, and RNH2 act as hydrogen/proton donors with a decreased capacity, leading to the release of oleic acid (RCOOH). The longer the radius of the coordinated atom is, the larger the size of the cyclic transition state is, which lowers the activation strain and the Gibbs free energy of activation for the release of RCOOH. From the resulting RCOOCdSe–PPh2, for the formation of Ph2P–CdSe–PPh2 (G), SePPh2H acts as a catalyst, in which the turnover frequency determining transition state (TDTS) is characteristic of the Se–P bond cleavage. For the formation of RHN–CdSe–PPh2 (H), SePPh2H also serves as a catalyst, in which the TDTS is representative of the N–H bond cleavage. For the formation of Ph2PSe–CdSe–NHR (I), HPPh2 behaves as a catalyst, in which the TDTS is typical of the Se–P and N–H bond cleavage. The rate constants increase as kI < kH < kG, which is in good agreement with our previous experimental observations reported. The present study brings insight into the use of additives such as HPPh2 and RNH2 to synthesize colloidal quantum dots.

An extensive study was conducted to explore the catalytic reduction of NO by CO on Rh4+ clusters at the ground and first excited states at the B3LYP/6-311+G(2d), SDD level. The main reaction pathway includes the following elementary steps: (1) the coadsorption of NO and CO; (2) the recombination of NO and CO molecules to form CO2 molecules and N atoms, or the decomposition of NO to N and O atoms; (3) the reaction of the N atom with the second adsorbed NO to form N2O; (4) the decomposition of N2O to N2 molecules and O atoms; and (5) the recombination of O atoms and CO to form CO2. At low temperatures (300–760 K), the turnover frequency (TOF)-determining transition state (TDTS) is the simultaneous C–O bond formation and N–O bond cleavage, with a rate constant (s−1) of kPs = 4.913 × 1012 exp(−272 724/RT). The formation of CO2 should originate in half from the reaction between the adsorbed CO and NO. The presence of CO in some degree decreases the catalytic reduction temperature of NO on the Rh4+ clusters. At high temperatures (760–900 K), the TDTS is applied to the N–O bond cleavage, with a rate constant (s−1) of kPa = 6.721 × 1015 exp(−318376/RT). The formation of CO2 should stem solely from the surface reaction between the adsorbed CO and the O atom, the latter originating from NO decomposition. The bridge NbRh4+ is thermodynamically preferred. Once the bridge NbRh4+ is formed, N2O- and NCO-contained species are predicted to exist, which is in good agreement with the experimental results.

The activation mechanism of C2H6 on a Pt4 cluster has been theoretically investigated in the ground state and the first excited state potential energy surfaces at the BPW91/Lanl2tz, aug-cc-pvtz//BPW91/Lanl2tz, 6-311++G(d, p) level. On the Pt4 cluster, the optimal channel order was kinetically as follows: demethanation > dehydrogenation > deethylenation from C2H6. The two-fold dehydrogenation of ethane to acetylene was almost equivalent to its single dehydrogenation to ethylene, both thermodynamically and kinetically. In addition, the C–H cleavage intermediate was kinetically more preferable than the C–C cleavage intermediate, while both the C–H cleavage intermediate and the C–C cleavage intermediate were thermodynamically favoured. Nevertheless, the extremely stable C–H cleavage intermediate was trapped in a deep well, which hindered the release of H2. Together with the excellent reactivity of the Pt4 cluster, for the design of an efficient and selective catalyst towards the dehydrogenation of C2H6, one can expect that it is necessary to improve the release of H2 from the C–H cleavage intermediate by introducing some additive or support into the Pt4 cluster, which decreases the binding of the catalyst towards H2. Concerning selectivity, the Pt atom was the most favourable for the dehydrogenation, the Pt2 cluster was the most preferable for deethylenation, and the Pt4 cluster was the most beneficial for the demethanation. Both Pt4 and Pt2 clusters exhibited more promising catalytic performance compared with the mononuclear Pt atom towards C2H6 activation.

The activation mechanism of C3H8 catalyzed by the homonuclear bimetallic Pt2 cluster has been detailedly explored on the singlet and triplet potential energy surfaces at BPW91/aug-cc-pvtz, Lanl2tz level. The C–H bond cleavage channel (dehydrogenation and the release of propylene) is kinetically predominant, whereas the C–C bond cleavage channel (demethanation and the release of ethane) should be ruled out. Furthermore, the release of propylene channel is kinetically favorable, while the dehydrogenation channel is thermodynamically preferable. Besides, both the C–H cleavage intermediate (Pt2H2C3H6b) and the C–C cleavage intermediates (CH3HPt2CHCH3 and CH3PtPtHC2H4) are thermodynamically preferred. The C–H cleavage intermediate (Pt2H2C3H6b) is kinetically favored, while the C–C cleavage intermediates (CH3HPt2CHCH3 and CH3PtPtHC2H4) are kinetically hindered. The homonuclear bimetallic Pt2 cluster toward propane exhibits higher reactivity than the Pt atom, which is in good agreement with the experimental observation.

The coordination of cyclic β-d-glucose (CDG) to both [Al(OH)(aq)]2+ and [Al(OH)2(aq)]1+ ions has been theoretically investigated, using quantum chemical calculations at the PBE0/6-311++G(d,p), aug-cc-pvtz level under polarizable continuum model IEF-PCM, and molecular dynamics simulations. [Al(OH)(aq)]2+ ion prefers to form both six- and five-coordination complexes, and [Al(OH)2(aq)]+ ion to form four-coordination complex. The two kinds of oxygen atoms (on hydroxyl and ring) of CDG can coordinate to both [Al(OH)(aq)]2+ and [Al(OH)2(aq)]+ ions through single-O-ligand and double-O-ligand coordination, wherein there exists some negative charge transfer from the lone pair electron on 2p orbital of the coordinated oxygen atom to the empty 3s orbital of aluminum atom. The charge transfer from both the polarization and H-bond effects stabilizes the coordinated complex. When the CDG coordinates to both [Al(OH)(H2O)4]2+ and [Al(OH)2(H2O)2]1+ ions, the exchange of water with CDG would take place. The six-coordination complex [(ηO4,O62-CDG)Al(OH)(H2O)3]2+ and the five-coordination complex [(ηO4,O62-CDG)Al(OH)2(H2O)]1+ are predicted to be the thermodynamically most preferable, in which the polarization effect plays a crucial role. The molecular dynamics simulations testify the exchange of water with CDG, and then support a five-coordination complex [(ηO4,O62-CDG)Al(OH)2(H2O)]1+ as the predominant form of the CDG coordination to [Al(OH)2(aq)]1+ ion.

The reaction mechanism of Pt2 cluster with C2H6 has been theoretically investigated on the singlet and triplet potential energy surfaces at BPW91/aug-cc-pvtz, Lanl2tz level. The deethylenation channel (Pt2H2 + C2H4) is kinetically favorable with the rate constant (in dm3 mol−1 s−1) of \(k = 1.8 \times 10^{6} \exp (-18,277/RT)\), while the dehydrogenation channel (Pt2C2H4 + H2) is thermodynamically preferable. The twofold dehydrogenation of ethane to acetylene by Pt2 cluster is both thermodynamically and kinetically almost equivalent to the single dehydrogenation to ethylene. In addition, both the C–H cleavage intermediate (H)2Pt2C2H4 and the C–C cleavage intermediate CH3HPtPtCH2 are thermodynamically favored in the Pt2 + C2H6 reaction. Furthermore, (H)2Pt2C2H4 is kinetically preferred, while CH3HPtPtCH2 is kinetically hindered. According to analysis of activation strain model, the stabilizing interaction \(\Updelta E^{ \ne }_{\text{int}}\)prefers the C–H bond cleavage, while the activation strain \(\Updelta E^{ \ne }_{\text{strain}}\)favors the C–C bond cleavage. From C–C to C–H bond cleavage, the lowering of activation barrier is mainly caused by the transition states interaction \(\Updelta E^{ \ne }_{\text{int}}\)becoming more stabilizing. Compared with mononuclear Pt atom, Pt2 cluster exhibits a more promising catalyst, because the synchronous effect of the atoms of Pt2 cluster makes two C–H bonds of C2H6 break simultaneously and then kinetically releases C2H4 readily from C2H6. This result is in good agreement with the experimental observation. Moreover, Pt2 cluster exhibits more efficient twofold dehydrogenation from ethane.

The gas-phase reaction mechanism of NO and CO catalyzed by Rh atom has been systematically investigated on the ground and first excited states at CCSD(T)//B3LYP/6-311+G(2d), SDD level. This reaction is mainly divided into two reaction stages, NO deoxygenation to generate N2O and then the deoxygenation of N2O with CO to form N2 and CO2. The crucial reaction step deals with the NO deoxygenation to generate N2O catalyzed by Rh atom, in which the self-deoxygenation of NO reaction pathway is kinetically more preferable than that in the presence of CO. The minimal energy reaction pathway includes the rate-determining step about N–N bond formation. Once the NO deoxygenation with CO catalyzed by rhodium atom takes place, the reaction results in the intermediate RhN. Then, the reaction of RhN with CO is kinetically more favorable than that with NO, while both of them are thermodynamically preferable. These results can qualitatively explain the experimental finding of N2O, NCO, and CN species in the NO + CO reaction. For the N2O deoxygenation with CO catalyzed by rhodium atom, the reaction goes facilely forward, which involves the rate-determining step concerning CO2 formation. CO plays a dominating role in the RhO reduction to regenerate Rh atom. The complexes, OCRhNO, RhON2, RhNNO, ORhN2, RhCO2, RhNCO, and ORhCN, are thermodynamically preferred. Rh atom possesses stronger capability for the N2O deoxygenation than Rh+ cation.

The peroxo dizinc Zn2O2 complex Q coordinated by imidazole and carboxylate groups for each Zn center has been designed to model the hydroxylase component of methane monooxygenase (MMO) enzyme, on the basis of the experimentally available structure information of enzyme with divalent zinc ion and the MMO with Fe2O2 core. The reaction mechanism for the hydroxylation of methane and its derivatives catalyzed by Q has been investigated at the B3LYP*/cc-pVTZ, Lanl2tz level in protein solution environment. These hydroxylation reactions proceed via a radical-rebound mechanism, with the rate-determining step of the C–H bond cleavage. This radical-rebound reaction mechanism is analogous to the experimentally available MMOs with diamond Fe2O2 core accompanied by a coordinate number of six for the hydroxylation of methane. The rate constants for the hydroxylation of substrates catalyzed by Q increase along CH4 < CH3F < CH3CN ≈ CH3NO2 < CH3CH3. Both the activation strain ΔE≠strain and the stabilizing interaction ΔE≠int jointly affect the activation energy ΔE≠. For the C–H cleavage of substrate CH3X, with the decrease of steric shielding for the substituted CH3X (X = F > H > CH3 > NO2 > CN) attacking the O center in Q, the activation strain ΔE≠strain decreases, whereas the stabilizing interaction ΔE≠int increases. It is predicted that the MMO with peroxo dizinc Zn2O2 core should be a promising catalyst for the hydroxylation of methane and its derivatives.

The reaction mechanism of methane dehydrogenation on monomeric Rh center located on (100) γ-alumina has been theoretically investigated at the PBE0/cc-pVTZ, SDD level. The (100) face of γ-alumina support is represented by an Al8O26H28 cluster, which is cut out from the ideal crystal structure. Then, two model Rh/γ-Al2O3 catalysts, in which Rh center interacts with one oxygen or two oxygen atoms of the (100) surface of γ-Al2O3, have been compared and denoted as Rh/Al8O26H27 and Rh/Al8O26H26, respectively. Toward methane activation, the model catalyst Rh/Al8O26H27 exhibits better performance than Rh/Al8O26H26. For the first CH bond cleavage of methane, the lowering of activation barriers on Rh/Al8O26H27 is mainly caused by lower substrate activation strain ΔE≠strain[substr], which is from substrate equilibrium geometry to the geometry it adopts in the TS, in comparison with that on Rh/Al8O26H26. These results are in qualitative agreement with the experimental results, where the partially reduced Rh+ is one of the active sites for methane dissociation.Highlights► Two model Rh/γ-Al2O3 catalysts are designed as Rh/Al8O26H27 and Rh/Al8O26H26. ► Rh/Al8O26H27 is more active toward methane activation than Rh/Al8O26H26. ► Lower substrate activation strain ΔE≠strain[substr] causes lower of activation barriers. ► These results are in qualitative agreement with the experimental results.

The reaction mechanism of the gas-phase Pt atom with C2H6 has been systematically studied on the singlet and triplet potential energy surfaces at CCSD(T)//BPW91/6-311++G(d, p), Lanl2dz level. For the formation of the main products, PtC2H4 + H2 and (H)2Pt + C2H4, the minimal energy reaction pathway involves the rate-determining step of the release of a H2 or ethene molecule by a reductive elimination mechanism at the exit. For the formation of the side products, PtCH2 + CH4, the optimal pathway proceeds through the σ-complex cis-HPtC2H5 from initial C–H bond cleavage, which assists the C–C σ-bond metathesis. This reactivity mode is complementary for the classical reactivity picture through the C–C cleavage intermediate M(CH3)2. Besides, these results are in qualitative agreement with the experimental results, in which the C–H insertion product is experimentally observed and the C–C insertion product is not formed in observable quantity.Graphical abstractHighlights► The major and minor reaction channels lead to PtC2H4 + H2 and PtCH2 + CH4, respectively. ► For the formation of PtCH2 + CH4, the optimal pathway proceeds through the σ-complex cis-HPtC2H5. ► These results are in reasonable agreement with experimental observation in Pt + C2H6 system.

The gas-phase reaction mechanism between rhodium monoxide cation and methane has been investigated on the singlet and triplet state potential energy surfaces at the CCSD(T)/6-311+G(2d,2p), SDD//B3LYP/6-311+G(2d,2p), SDD level. Over the 300–1100 K temperature range, the branching ratios of Rh+ + CH3OH and RhCH2+ + H2O are 83.8–52.6% and 16.2–47.4%, respectively, whereas the branching ratio of CH2ORh+ + H2 is so small to be negligible. For the main products (Rh+ + CH3OH and RhCH2+ + H2O) formation, the minimum energy reaction pathway involves singlet–triplet spin inversion, and both b-RhCH3OH+ and H2ORhCH2+ are the energetically preferred intermediates. Alternatively, in the CH2ORh+ + H2 reaction, both b-RhCH3OH+ and H2RhOCH2+ are the energetically favorable intermediates, and the main products are Rh+ + CH3OH. In the RhCH2+ + H2O reaction, the main products are Rh+ + CH3OH with the energetically predominant intermediate b-RhCH3OH+. In the reaction of Rh+ + CH3OH, both b-RhCH3OH+ and H2RhOCH2+ are the energetically preferable intermediates, and the main products are CH2ORh+ + H2. Besides, toward methane activation, the cation RhO+ exhibits higher reaction efficiency than the cation Rh+, the neutral RhO, and its first-row congener CoO+, and it exhibits lower methanol branching ratio and higher water branching ratio than RhO and CoO+.

•Pure Ni2P and Ni12P5 crystallites formed on the AC by controlling Ni/P ratios.•Ni12P5 presence profitably affected the dispersion of Ni2P.•High dispersion of Ni12P5 and Ni2P favors the oil yield and C15 selectivity.•The synergy of Ni12P5 and Ni2P facilitated the formation of branched alkanes.•High oil yield of 56.0% with a high heating value of 46.5 MJ kg−1 was obtained.A series of activated carbon (AC)-supported nickel phosphide catalysts were prepared; characterized using XRD, XPS, TEM, and NH3-TPD techniques; and evaluated for the deoxygenation of palmitic acid. The formation of Ni2P and/or Ni12P5 on the surface of AC could be controlled by controlling the Ni/P molar ratios. With low Ni/P molar ratios from 0.5 to 0.8, only crystalline Ni2P formed. Both Ni2P and Ni12P5 formed with Ni/P ratios of 1.0 and 1.5, whereas only Ni12P5 formed with a Ni/P ratio of 2.0. As the Ni/P ratio further increased (Ni/P ≥ 3.0), crystalline Ni formed in addition to Ni12P5. The deoxygenation activities of the NixP/AC catalysts were strongly dependent on the types and dispersion of the nickel phosphide. The oil yield and C15 selectivity on the catalysts followed the sequence Ni1.5P/AC > Ni2.0P/AC > Ni1.0P/AC ≈ Ni3.0P/AC > Ni4.0P/AC > Ni0.5P/AC ≈ Ni0.8P/AC, Ni1.0P/AC > Ni1.5P/AC ≈ Ni0.8P/AC > Ni0.5P/AC ≈ Ni2.0P/AC > Ni3.0P/AC > Ni4.0P/AC, respectively. The high activity was attributed to the coexistence and high dispersion of Ni2P and Ni12P5, which were favorable for branched alkanes formation, C15 selectivity improvement and oil yield increase. Due to the high-grade diesels (HV = 46.5 MJ kg−1) obtained, NixP/AC can be considered to be a very promising catalyst for transforming fatty acids into high-grade diesel.Download high-res image (194KB)Download full-size image

The peroxo dizinc Zn2O2 complex Q coordinated by imidazole and carboxylate groups for each Zn center has been designed to model the hydroxylase component of methane monooxygenase (MMO) enzyme, on the basis of the experimentally available structure information of enzyme with divalent zinc ion and the MMO with Fe2O2 core. The reaction mechanism for the hydroxylation of methane and its derivatives catalyzed by Q has been investigated at the B3LYP*/cc-pVTZ, Lanl2tz level in protein solution environment. These hydroxylation reactions proceed via a radical-rebound mechanism, with the rate-determining step of the C–H bond cleavage. This radical-rebound reaction mechanism is analogous to the experimentally available MMOs with diamond Fe2O2 core accompanied by a coordinate number of six for the hydroxylation of methane. The rate constants for the hydroxylation of substrates catalyzed by Q increase along CH4 < CH3F < CH3CN ≈ CH3NO2 < CH3CH3. Both the activation strain ΔE≠strain and the stabilizing interaction ΔE≠int jointly affect the activation energy ΔE≠. For the C–H cleavage of substrate CH3X, with the decrease of steric shielding for the substituted CH3X (X = F > H > CH3 > NO2 > CN) attacking the O center in Q, the activation strain ΔE≠strain decreases, whereas the stabilizing interaction ΔE≠int increases. It is predicted that the MMO with peroxo dizinc Zn2O2 core should be a promising catalyst for the hydroxylation of methane and its derivatives.

An extensive study was conducted to explore the catalytic reduction of NO by CO on Rh4+ clusters at the ground and first excited states at the B3LYP/6-311+G(2d), SDD level. The main reaction pathway includes the following elementary steps: (1) the coadsorption of NO and CO; (2) the recombination of NO and CO molecules to form CO2 molecules and N atoms, or the decomposition of NO to N and O atoms; (3) the reaction of the N atom with the second adsorbed NO to form N2O; (4) the decomposition of N2O to N2 molecules and O atoms; and (5) the recombination of O atoms and CO to form CO2. At low temperatures (300–760 K), the turnover frequency (TOF)-determining transition state (TDTS) is the simultaneous C–O bond formation and N–O bond cleavage, with a rate constant (s−1) of kPs = 4.913 × 1012 exp(−272 724/RT). The formation of CO2 should originate in half from the reaction between the adsorbed CO and NO. The presence of CO in some degree decreases the catalytic reduction temperature of NO on the Rh4+ clusters. At high temperatures (760–900 K), the TDTS is applied to the N–O bond cleavage, with a rate constant (s−1) of kPa = 6.721 × 1015 exp(−318376/RT). The formation of CO2 should stem solely from the surface reaction between the adsorbed CO and the O atom, the latter originating from NO decomposition. The bridge NbRh4+ is thermodynamically preferred. Once the bridge NbRh4+ is formed, N2O- and NCO-contained species are predicted to exist, which is in good agreement with the experimental results.