Potential energy surfaces and mechanisms for activation of ethane by gas-phase Pt+: A density functional study

Ye, Peng; Ye, Q.; Zhang, Ganbing; Cao, Zexing

doi:10.1016/j.cplett.2010.11.015

Cited by 12 publications

(17 citation statements)

References 45 publications

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“…Thus, the dissociation of the second C-H bond represents the rate determining reaction step which is in agreement with the reactive behavior of Pt + and Pt x + clusters [37,53] but in contrast to the findings for neutral cuboidal Ir clusters [57].…”

Section: Introductionsupporting

confidence: 86%

“…Exceptions are the late 4d metals Ru + and Rh + which catalyze the formation of MC 2 H 4 + + H 2 in an exothermic reaction [33][34][35][36]. Among the 5d metals, all so far 60 studied cations, Ta + , Os + , Pt + , and Au + are able to dehydrogenate ethane in an exothermic reaction [37][38][39][40][41][42]. Furthermore, ligated platinum PtL + (L = CH 2 , 2,2'-bipyridine, 2-phenylpyridine, 7,8benzoquinoline) [43,44] and iron FeL + (L = NH) [45] cations as well as Si + and La + were found to form H 2 from ethane [46,47] whereas Al + , Lu + , and U + are unreactive [47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

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Selective C H bond activation of ethane by free gold clusters

Lang

Bernhardt

Bakker

et al. 2019

International Journal of Mass Spectrometry

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The activation and potential dissociation of ethane mediated by small cationic gold clusters Au x + (x = 2-4) has been explored by infrared multiphoton dissociation (IR-MPD) spectroscopy and density functional theory (DFT) calculations. The calculations show that the interaction between the gold clusters and ethane is mainly governed by the mixing of the ethane CH 3 bond-forming orbitals-(CH 3) with gold d-orbitals. While the CC single bond appears to be unaffected, this mixing leads to the selective activation of up to two ethane C-H bonds and a reduction of the activation barrier for C-H bond dissociation to up to 0.82 eV, making the reaction kinetically feasible at room temperature. In agreement with this, experimental IR-MPD spectra of the complexes Au 2 (C 2 H 6) 2 + and Au 2 (C 2 D 6) 2 + reveal that the dominant product is one where a single ethane C-H bond is dissociated resulting in a complex which contains an ethyl group and a bridge-bonded H atom along with a second, adsorbed C 2 H 6 molecule. A similar C-H bond dissociation mechanism is theoretically predicted for the Au 3 (C 2 H 6) y + (y = 2,3) and Au 4 (C 2 H 6) y + (y = 2,3) complexes, albeit thermodynamically less favorable. IR-MPD spectra of Au 3 (C 2 H 6) y + (y = 2,3) and Au 4 (C 2 H 6) y + (y = 2,3) confirm the encounter product to be the dominant one, although the coexistence of isomers containing ethyl groups cannot be excluded. Various pathways for C-H bond activation are theoretically explored and the ethane activation mechanism is compared to the gold mediated activation of methane and ethylene. 65 spectra (I 0) in between successive FELICE pulses. The IR-MPD spectra shown in this contribution display the ratio 65

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Section: Introductionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Selective C H bond activation of ethane by free gold clusters

Lang

Bernhardt

Bakker

et al. 2019

International Journal of Mass Spectrometry

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“…However, when the distance between the H 2 molecule and the platinum center is increased incrementally, at a certain Pt À H bond length (Dd = 1.630 ), an isomerization takes place that results in a switch of the C 2 H 4 (10) the neutral ligand is coordinated trans to nitrogen, and that for 10 no isomer can be located on the PES, in which the C 2 H 4 ligand is oriented trans to the platinum-bound carbon atom). In conclusion, this scenario, in which counterintuitively the loss of H 2 is associated with a high barrier, is the consequence of the trans effect exerted by C pyridyl , which makes coordination of fragments trans to this carbon atom energetically unfavorable.…”

Section: Resultsmentioning

confidence: 79%

“…For example, in the exothermic reactions of platinum clusters Pt n + ( n =1–21) with ethane, [Pt n ,C 2 ,H 4 ] + and H 2 are generated;3 according to computational studies and deuterium‐labeling experiments, both 1,1‐ and 1,2‐elimination pathways have to be taken into account 3. 4 Although the attachment of ligands to bare metal ions often reduces their reactivity, the selectivity might be increased 5. However, ligands can also actively participate in chemical reactions rather than being mere spectators 6.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Studies on the Gas‐Phase Dehydrogenation of Alkanes at Cyclometalated Platinum Complexes

Butschke

Schwarz

2012

Chemistry A European J

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In the ion/molecule reactions of the cyclometalated platinum complexes [Pt(L-H)](+) (L=2,2'-bipyridine (bipy), 2-phenylpyridine (phpy), and 7,8-benzoquinoline (bq)) with linear and branched alkanes C(n)H(2n+2) (n=2-4), the main reaction channels correspond to the eliminations of dihydrogen and the respective alkenes in varying ratios. For all three couples [Pt(L-H)](+)/C(2)H(6), loss of C(2)H(4) dominates clearly over H(2) elimination; however, the mechanisms significantly differs for the reactions of the "rollover"-cyclometalated bipy complex and the classically cyclometalated phpy and bq complexes. While double hydrogen-atom transfer from C(2)H(6) to [Pt(bipy-H)](+), followed by ring rotation, gives rise to the formation of [Pt(H)(bipy)](+), for the phpy and bq complexes [Pt(L-H)](+), the cyclometalated motif is conserved; rather, according to DFT calculations, formation of [Pt(L-H)(H(2))](+) as the ionic product accounts for C(2)H(4) liberation. In the latter process, [Pt(L-H)(H(2))(C(2)H(4))](+) (that carries H(2) trans to the nitrogen atom of the heterocyclic ligand) serves, according to DFT calculation, as a precursor from which, due to the electronic peculiarities of the cyclometalated ligand, C(2)H(4) rather than H(2) is ejected. For both product-ion types, [Pt(H)(bipy)](+) and [Pt(L-H)(H(2))](+) (L=phpy, bq), H(2) loss to close a catalytic dehydrogenation cycle is feasible. In the reactions of [Pt(bipy-H)](+) with the higher alkanes C(n)H(2n+2) (n=3, 4), H(2) elimination dominates over alkene formation; most probably, this observation is a consequence of the generation of allyl complexes, such as [Pt(C(3)H(5))(bipy)](+). In the reactions of [Pt(L-H)](+) (L=phpy, bq) with propane and n-butane, the losses of the alkenes and dihydrogen are of comparable intensities. While in the reactions of "rollover"-cyclometalated [Pt(bipy-H)](+) with C(n)H(2n+2) (n=2-4) less than 15 % of the generated product ions are formed by C-C bond-cleavage processes, this value is about 60 % for the reaction with neo-pentane. The result that C-C bond cleavage gains in importance for this substrate is a consequence of the fact that 1,2-elimination of two hydrogen atoms is no option; this observation may suggest that in the reactions with the smaller alkanes, 1,1- and 1,3-elimination pathways are only of minor importance.

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“…It is reported that the transition metal Pt (neutral, cationic, or clusters) are the efficient C-H insertion agents [23–29]. However, as far as we know, although a few investigations of C-H insertion processes have focused on the neutral Pt atom [23–27], the C-C insertion has hardly been investigated in the gas phase.…”

Section: Introductionmentioning

confidence: 99%

Activation of Propane C-H and C-C Bonds by Gas-Phase Pt Atom: A Theoretical Study

Yang

et al. 2012

IJMS

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The reaction mechanism of the gas-phase Pt atom with C3H8 has been systematically investigated on the singlet and triplet potential energy surfaces at CCSD(T)//BPW91/6-311++G(d, p), Lanl2dz level. Pt atom prefers the attack of primary over secondary C-H bonds in propane. For the Pt + C3H8 reaction, the major and minor reaction channels lead to PtC3H6 + H2 and PtCH2 + C2H6, respectively, whereas the possibility to form products PtC2H4 + CH4 is so small that it can be neglected. The minimal energy reaction pathway for the formation of PtC3H6 + H2, involving one spin inversion, prefers to start at the triplet state and afterward proceed along the singlet state. The optimal C-C bond cleavages are assigned to C-H bond activation as the first step, followed by cleavage of a C-C bond. The C-H insertion intermediates are kinetically favored over the C-C insertion intermediates. From C-C to C-H oxidative insertion, the lowering of activation barrier is mainly caused by the more stabilizing transition state interaction ΔE≠int, which is the actual interaction energy between the deformed reactants in the transition state.

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Potential energy surfaces and mechanisms for activation of ethane by gas-phase Pt+: A density functional study

Cited by 12 publications

References 45 publications

Selective C H bond activation of ethane by free gold clusters

Selective C H bond activation of ethane by free gold clusters

Mechanistic Studies on the Gas‐Phase Dehydrogenation of Alkanes at Cyclometalated Platinum Complexes

Activation of Propane C-H and C-C Bonds by Gas-Phase Pt Atom: A Theoretical Study

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