Enabling enelike reactions on Si (111) -7×7 through tuning organic molecular structures

摘要

We previously demonstrated that acetonitrile (NC CH_3) binds to the adjacent adatom-rest atom pair of Si (111) -7×7 through a [2+2] -like cycloaddition reaction, forming a (Si) NC (Si) CH_3 -like surface species [Tao, J. Phys. Chem. B 106, 3890 (2002)]. Current investigation clearly showed that chloroacetonitrile (NC CH_2 Cl), propargyl chloride (HCC CH_2 Cl), and 3-chloropropionitrile (NC CH_2 CH_2 Cl) react with the surface via enelike reactions, concurrently involving NC/CC as well as the breakage of the CCl/CH bond. Further separation of the unsaturated bond (CC) from the CCl bond using CH_2 spacers in 5-chloro-1-pentyne (CHC CH_2 CH_2 CH_2 Cl) would direct the reaction to a [2+2] -like cycloaddition. These experimental results clearly suggest the possibility of controlling the surface reaction pathways by tuning the organic molecular structures. This strategy can be useful in designing and fabricating functional molecular templates on Si (111) -7×7.