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Wang, Po-Kang; Slichter, Charles P.; Sinfelt, J. H.

doi:10.1103/physrevlett.53.82

Cited by 136 publications

(61 citation statements)

References 19 publications

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“…The same NMR experiments measured the C-C bond length of adsorbed CCH 2 to be 1.44 ( 0.05 Å, 54 in reasonable agreement with our calculations, which lead to a C-C distance of 1.392 Å and 87.92 kcal/mol binding energy.…”

Section: Hcch and Cchsupporting

confidence: 89%

Chemisorption of (CH_xand C₂H_y) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies

Jacob

Goddard

2004

J. Phys. Chem. B

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We used the B3LYP flavor of density functional theory (DFT) to study the chemisorption of all CH x and C 2 H y intermediates on the Pt(111) surface. The surface was modeled with the 35 atom Pt 14.13.8 cluster, which was found to be reliable for describing all adsorption sites. We find that these hydrocarbons all bind covalently (σ-bonds) to the surface, in agreement with the studies by Kua and Goddard on small Pt clusters. In nearly every case the structure of the adsorbed hydrocarbon achieves a saturated configuration in which each C is almost tetrahedral with the missing H atoms replaced by covalent bonds to the surface Pt atoms. Thus, (Pt 3 )-CH prefers a µ 3 hollow site (fcc), (Pt 2 )CH 2 prefers a µ 2 bridge site, and PtCH 3 prefers µ 1 on-top sites. Vinyl leads to (Pt 2 )CH-CH 2 (Pt), which prefers a µ 3 hollow site (fcc). The only exceptions to this model are ethynyl (CCH), which binds as (Pt 2 )CdCH(Pt), retaining a CC π-bond while binding at a µ 3 hollow site (fcc), and HCCH, which binds as (Pt)HCdCH(Pt), retaining a π bond that coordinates to a third atom of a µ 3 hollow site (fcc) to form an off center structure. These structures are in good agreement with available experimental data. For all species we calculated heats of formation (∆H f ) to be used for considering various reaction pathways on Pt(111). For conditions of low coverage, the most strongly bound CH x species is methylidyne (CH, BE ) 146.61 kcal/mol), and ethylidyne (CCH 3 , BE ) 134.83 kcal/mol) among the C 2 H y molecules. We find that the net bond energy is nearly proportional to the number of C-Pt bonds (48.80 kcal/mol per bond) with the average bond energy decreasing slightly with the number of C ligands.

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Section: Hcch and Cchsupporting

confidence: 89%

Chemisorption of (CH_xand C₂H_y) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies

Jacob

Goddard

2004

J. Phys. Chem. B

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“…Solid state NMR has long been used to identify and characterize the structures of small organic molecules adsorbed onto catalytic surfaces [10][11][12], argon matrices [13], silica and alumina surfaces [14][15][16]. There similarly exist a number of solid state NMR pulse techniques capable in principle of reporting the structures of surface-adsorbed proteins.…”

Section: Nmr Methods For the Study Of Protein Structure At Biomateriamentioning

confidence: 99%

“…These models are derived from the full set of 1,000 models. Alignment of the models in the figure was based on root-mean-square deviation calculation of segments (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) and (33)(34)(35)(36)(37)(38) between the 8 models. Table 1 31 P-31 P nearest neighbor distances lying within a sphere of radius 6 Å for the 004 crystal plane in in monoclinic HAP.…”

Section: Figmentioning

confidence: 99%

Solid state NMR studies of molecular recognition at protein–mineral interfaces

Goobes

Stayton

Drobny

2007

Progress in Nuclear Magnetic Resonance Spectroscopy

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“…Indirect evidence for the bonding geometry of CCH 2 on Rh(lll) comes from studies of CCH 2 on Pt. On Pt(lll), CCH 2 has a similar HREEL spectrum [16] and presumably similar bonding to Rh(lll), while nuclear magnetic resonance studies of acetylene adsorption adsorbed species as CCH 2 [60]. et.…”

Section: Effects Of Coadsorbed Carbon Monoxidementioning

confidence: 99%

The surface structure and thermal decomposition of acetylene on the Rh(111) single crystal surface and the effect of coadsorbed carbon monoxide

et al. 1988

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The surface structure and thermal chemistry of acetylene. on the Rh(lll) crystal surface have been studied from 30 to BOO K using high resolution electron energy loss spectroscopy (HREELS), low energy electron diffraction (LEEO), and thermal desorption spectroscopy (TDS). Adsorbed acetylene on the Rh(lll) is disordered at 30 K, but orders into a (2 x 2) LEED structure at 60 K; this is the lowest ordering temperature that has been reported for chemisorbed acetylene on a metal surface. HREEL spectra of c 2 H 2 and c 2 D 2 ordered in the (2 x 2) structure at 77 K on Rh(lll) indicate that the 2 3carbon-carbon bond of chemisorbed acetylene rehybridizes between sp and sp At 270 K, chemisorbed molecular acetylene decomposes predominantly to CCH 2 species. Above 400 K, further decomposition to a mixture of CCH and CH species h observed. When CO and molecular acetylene are coadsorbed at 220 K, we observe a c(4 x 2) LEED structure rather than the (2 x 2) LEED structures observed for acetylene or CO adsorbed alone on Rh(lll). Also, chemisorbed acetylene, when coadsorbed with CO, decomposes at 270 K to a mixture of CCH 3 (ethylidyne) and CCH {acetylide) species rather than the CCH 2 species. 1. INTRODUCTION Studies of the bonding and reactivity of unsaturated hydrocarbon molecules adsorbed on transition metal single crystal surfaces are important for a molecular-level understanding of heterogeneous hydrocarbon catalysis. With the development over the last 20 years of ultra-high vacuum {UHV) technology and of surface sensitive spectroscopies, a data base of adsorption geometries and fragmentation pathways for prototype hydrocarbons adsorbed on well-defined -2 -single crystal metal surfaces is now accumulating.High resolution electron energy loss spectroscopy (HREELS) [1], in providing surface vibrational spectra, has been a particularly powerful technique for determining the identity of hydrocarbon adsorbates. In combination with other techniques like low energy electron diffraction (LEED) [2], it has also been possible to determine the adsorption geometry, the bond lengths and the bond angles for several hydrocarbon adsorbates.[3] These structural results have been well-complemented by the desorption products and kinetics measured in thenmal desorption spectroscopy (TDS) studies.These techniques have been extensively applied to study the adsorption of acetylene, the prototype alkyne. To date, HREELS has been used to study the bonding and reactivity of acetylene adsorbed on Ni(111) [4][5][6][7], Ni(100) [B,9], Ni(110) [10,11], Pd(111) [12,13], Pd(100) [14], Pd(110) [10], Pt(lll) [15,16], Cu(111) [10], Cu(110) [17], Ag(110) [1B], Fe(110) [19], Fe(111) [20], Ru(0001) [21], Re(0001) [22], Rh(111) [23], W(110) [24], W(111) [25], W(lOO) [26], and Si(lll) [27] surfaces. One of the major observations of these studies (except for the Ag(1l0) surface) was a large shift of the carbon-carbon stretchingfrequency from its value of 1974 em in gas phase acetylene to 1100-1400 em for chemisorbed molecular acetylene. Such a frequency sh...

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NMR Study of the Structure of Simple Molecules Adsorbed on Metal Surfaces:C2H2

Cited by 136 publications

References 19 publications

Chemisorption of (CH_xand C₂H_y) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies

Chemisorption of (CH_xand C₂H_y) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies

Solid state NMR studies of molecular recognition at protein–mineral interfaces

The surface structure and thermal decomposition of acetylene on the Rh(111) single crystal surface and the effect of coadsorbed carbon monoxide

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NMR Study of the Structure of Simple Molecules Adsorbed on Metal Surfaces:C2H2

Cited by 136 publications

References 19 publications

Chemisorption of (CHxand C2Hy) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies

Chemisorption of (CHxand C2Hy) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies

Solid state NMR studies of molecular recognition at protein–mineral interfaces

The surface structure and thermal decomposition of acetylene on the Rh(111) single crystal surface and the effect of coadsorbed carbon monoxide

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Product

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Chemisorption of (CH_xand C₂H_y) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies

Chemisorption of (CH_xand C₂H_y) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies