Cycloaddition of Benzene on Si(100) and Its Surface Conversions

Thumbnail Image
Supplemental Files
Date
2005-02-01
Authors
Jung, Yousung
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Person
Research Projects
Organizational Units
Organizational Unit
Chemistry

The Department of Chemistry seeks to provide students with a foundation in the fundamentals and application of chemical theories and processes of the lab. Thus prepared they me pursue careers as teachers, industry supervisors, or research chemists in a variety of domains (governmental, academic, etc).

History
The Department of Chemistry was founded in 1880.

Dates of Existence
1880-present

Related Units

Journal Issue
Is Version Of
Versions
Series
Department
Abstract

A comprehensive ab initio study of the adsorption of benzene on the silicon(100) surface is presented. Five potential candidates ([2+2] adduct, [4+2] adduct, two tetra-σ-bonded structures, and one radical-like structure) for the reaction product are examined to determine the lowest energy adsorption configuration. A [4+2] butterfly structure is determined to be the global minimum (−29.0 kcal/mol), although one of the two tetra-σ-bonded structures (−26.7 kcal/mol) is similar in energy to it. Multireference perturbation theory suggests that the [4+2] addition mechanism of benzene on Si(100) is very similar to the usual Diels−Alder reaction (i.e., small or zero activation barrier), even though benzene adsorption entails the loss of benzene aromaticity during the reaction. On the other hand, the [2+2] cycloaddition mechanism is shown to require a relatively high activation barrier (17.8 kcal/mol), in which the initial step is to form a (relatively strongly bound) van der Waals complex (−8.9 kcal/mol). However, the net activation barrier relative to reactants is only 8.9 kcal/mol. Careful examination of the interconversion reactions among the reaction products indicates that the two tetra-σ-bonded structures (that are energetically comparable to the [4+2] product) can be derived from the [2+2] adduct with activation barriers of 15.5 and 21.4 kcal/mol. However, unlike the previous theoretical predictions, it is found that the conversion of the [4+2] product to the tetra-σ-bonded structures entails huge barriers (>37.0 kcal/mol) and is unlikely to occur. This suggests that the [4+2] product is not only thermodynamically the most stable configuration (lowest energy product) but also kinetically very stable (large barriers with respect to the isomerization to other products).

Comments

Reprinted (adapted) with permission from Journal of the American Chemical Society 127 (2005): 3131, doi:10.1021/ja0402093. Copyright 2005 American Chemical Society.

Description
Keywords
Citation
DOI
Subject Categories
Copyright
Sat Jan 01 00:00:00 UTC 2005
Collections