Adsorption mechanisms of isoxazole and oxazole on Si(100)-2 × 1 surface: Si-N dative bond addition vs. [4+2] cycloaddition.
The surface reaction pathways of isoxazole and oxazole on Si(100)-2 × 1 surface were theoretically investigated. They both form a weakly bound Si-N dative bond adduct on Si(100)-2 × 1 surface. In the case of isoxazole, the barrierlessly formed Si-N adduct is the most important surface product, that cannot be easily converted into other species. On the other hand, a facile concerted [4+2](CC) cycloaddition without involving the initial Si-N dative bond adduct was also found in the case of oxazole adsorption. The existence of Diels-Alder reactions is attributed to the particular arrangement of the two heteroatoms of oxazole in such a way that the two Si-C σ-bonds can be formed in a [4+2] fashion. In short, the unique geometric arrangements and electronegativity of these similar heteroatomic molecules yielded distinctively different surface reaction characteristics.
Department of Chemistry and Green-Nano Materials Research Center, College of Natural Sciences, Kyungpook National University, Taegu, South Korea.
Manik Kumer
MK
Ghosh
Cheol Ho
CH
Choi