Acetylene reaction with the Si(111) surface: A semiempirical quantum chemical study

Weiner, Brian; Carmer, C. S.; Frenklach, Michael

doi:10.1103/physrevb.43.1678

Cited by 32 publications

(18 citation statements)

References 29 publications

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“…Chemical reaction is most likely to take place at these dangling bonds. Previous work in this area mainly involves some unsaturated hydrocarbons containing unpolarized covalent bonds of CvC or CwC, including typical ethylene, 5,6 acetylene, [7][8][9] five-membered heterocyclic aromatics, [10][11][12][13] benzene, 14,15 aniline, 16 and chlorobenzene. 17, 18 These studies demonstrate that the adjacent adatom-rest atom pair can act as a ''diradical'' to react with unsaturated functional groups of organic molecules.…”

Section: Introductionmentioning

confidence: 99%

Selective attachment of benzonitrile on Si(111)-7×7: Configuration, selectivity, and mechanism

Tao

Wang²,

Chen³

et al. 2002

Phys. Rev. B

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The cycloaddition of benzonitrile with Si͑111͒-7ϫ7 has been investigated as a model system for understanding the interaction of conjugated -electron systems with Si͑111͒-7ϫ7 using high-resolution electron energy loss spectroscopy, x-ray photoelectron spectroscopy ͑XPS͒, ultraviolet photoelectron spectroscopy, scanningtunneling microscopy ͑STM͒, and density-functional-theory calculation ͑perturbative Beck-Perdew functional in conjugation with a basis set of DN**͒. Vibrational features of chemisorbed benzonitrile unambiguously demonstrate that the cyano group directly interacts with Si surface dangling bonds, evidenced in the disappearance of CwN stretching mode around 2256 cm Ϫ1 coupled with the appearance of CvN stretching mode at 1623 cm Ϫ1 and the retention of all vibrational signatures of phenyl ring. XPS shows that both C 1s and N 1s core levels of the cyano groups display large down-shifts by 2.5 and 1.5 eV, respectively, after chemisorption. A smaller down-shift of ϳ0.8 eV is observed for the C 1s core level of phenyl group due to the weaker inductive effect of the formed CvN groups in chemisorbed benzonitrile than that of CwN groups in physisorbed molecules. Compared with physisorbed molecules, the photoemission from CN orbitals of chemisorbed benzonitrile is significantly reduced, suggesting the direct involvement of CN in the surface binding. These experimental results show that the covalent attachment of benzonitrile on Si͑111͒-7ϫ7 occurs in a selective manner through the ͑2ϩ2͒ cycloaddition between the cyano group and the adjacent adatom-rest atom pair. The cycloadduct formed contains an intact phenyl ring protruding into vacuum, retaining aromaticity. This functionalized Si surface may serve as a substrate for further modification or act as an intermediate for fabrication of multilayer organic thin films or materials syntheses in vacuum.

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Section: Introductionmentioning

confidence: 99%

Selective attachment of benzonitrile on Si(111)-7×7: Configuration, selectivity, and mechanism

Tao

Wang²,

Chen³

et al. 2002

Phys. Rev. B

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“…5,6 Previous studies showed that the neighboring adatom-rest atom pair can serve as active reaction sites in the covalent binding of simple unsaturated organic molecules including ethylene, 7,8 acetylene, [9][10][11][12][13] benzene, 14,15 thiophene, 16,17 etc. The high reactivity observed in these chemical systems is attributable to the coexistence of electrophilic adatom and its neighboring nuclophilic rest atom with a reasonable spatial separation, leading to the feasible occurrence of ͓2ϩ2͔-like or/and ͓4ϩ2͔-like cycloaddition reactions on Si(111)-7ϫ7.…”

Section: Introductionmentioning

confidence: 99%

Tetra-σ attachment of allyl cyanide onSi(111)−7×7

Tao

Dai

2002

Phys. Rev. B

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The investigation of allyl cyanide adsorption on Si(111)-7ϫ7 using high-resolution electron-energy-loss spectroscopy ͑HREELS͒, x-ray photoelectron spectroscopy ͑XPS͒, and ultraviolet photoelectron spectroscopy ͑UPS͒ reveals a tetra-binding mode through two ͓2ϩ2͔-like cycloaddition reactions. The HREELS spectra of chemisorbed monolayer show the absence of CvC, CwN, and C(sp 2 )uH stretching modes coupled with the appearance of CvN stretching mode at ϳ1590 cm Ϫ1 , demonstrating that both the CvC and CwN of allyl cyanide directly participate in binding with the surface to form C-C and CvN bonds, respectively. This binding configuration was further confirmed in our XPS and UPS studies. The imine-containing skeleton formed on the surface can possibly be employed as a molecular template for a further modification of Si surfaces and syntheses in vacuum.

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“…3 In their approach, the MM portion of the calculation determines the positions of the atoms at the boundary of the QM portion; this in turn restricts the displacement of surface Si atoms. Maseras and Morokuma have recently developed a hybrid QM/MM method called the integrated molecular orbital molecular mechanics (IMOMM) method.…”

Section: Introductionmentioning

confidence: 99%

SIMOMM: An Integrated Molecular Orbital/Molecular Mechanics Optimization Scheme for Surfaces

1999

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Reactions on surfaces are often modeled using molecular clusters which are too small to accurately represent the mechanical environment of bulk materials. The small size of these clusters is driven by the large cost of ab initio quantum mechanical (QM) computational methods needed to accurately model chemical reactions. Hybrid computational approaches that interface quantum mechanics with molecular mechanics (MM) methods, commonly referred to as QM/MM methods, are becoming increasingly popular for treating large systems, but these hybrid methods have not been applied to surface models. This paper presents a QM/MM optimization scheme for modeling surfaces that is based on the IMOMM approach of Maseras and Morokuma. The modified method, (S)urface IMOMM, and its applications to surface chemistry are discussed. Disciplines Chemistry CommentsReprinted (adapted) ReceiVed: June 12, 1998; In Final Form: NoVember 20, 1998 Reactions on surfaces are often modeled using molecular clusters which are too small to accurately represent the mechanical environment of bulk materials. The small size of these clusters is driven by the large cost of ab initio quantum mechanical (QM) computational methods needed to accurately model chemical reactions. Hybrid computational approaches that interface quantum mechanics with molecular mechanics (MM) methods, commonly referred to as QM/MM methods, are becoming increasingly popular for treating large systems, but these hybrid methods have not been applied to surface models. This paper presents a QM/MM optimization scheme for modeling surfaces that is based on the IMOMM approach of Maseras and Morokuma. The modified method, (S)urface IMOMM, and its applications to surface chemistry are discussed.

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Acetylene reaction with the Si(111) surface: A semiempirical quantum chemical study

Cited by 32 publications

References 29 publications

Selective attachment of benzonitrile on Si(111)-7×7: Configuration, selectivity, and mechanism

Selective attachment of benzonitrile on Si(111)-7×7: Configuration, selectivity, and mechanism

Tetra-σ attachment of allyl cyanide onSi(111)−7×7

SIMOMM: An Integrated Molecular Orbital/Molecular Mechanics Optimization Scheme for Surfaces

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