A selective [4+2]-like cycloaddition of alpha,beta-unsaturated ketone on Si(111)-7 x 7

作者：Tang, Hai Hua; Cai, Ying Hui; Ning, Yue Sheng; Lai, Yee Hing; Xu, Guo Qin^*

来源：Surface Science, 2007, 601(16): 3293-3302.

DOI：10.1016/j.susc.2007.05.018

• ketones
• silicon
• electron energy loss spectroscopy (EELS)
• photoelectron spectroscopy
• density functional calculations
• chemisorption
• physical adsorption

The interaction of ethyl vinyl ketone (EVK) with Si(111)-7 x 7 has been investigated using high-resolution electron energy loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. The disappearance of both stretching vibrations of =CH2 (3099 cm(-1)) and C=O (1684 cm(-1)) coupled with the appearance of new C=C stretching mode (1660 cm(-1)) in the HREELS spectra of chemisorbed EVK clearly demonstrates the direct involvement of conjugated C=C and C=O bonds to form a (SiCH2CH)-H-1-H-2=C-3((CH2CH3)-H-4-H-5)OSi surface species via [4 + 2]-like cycloaddition in a highly selective manner. In addition, XPS studies show that the Cls binding energies of C-1/C-2 and C-3 upon chemisorption display chemical downshifts of 0.8 eV and 2.2 eV, respectively, further confirming the proposed [4 + 2]-like cycloaddition reaction for the EVK/Si(111)-7 x 7 system. DFT theoretical calculations suggest that the proposed [4 + 2]-like cycloadduct is thermodynamically most favorable.

• 出版日期2007-8-15