AVS 46th International Symposium
    Surface Science Division Friday Sessions
       Session SS2-FrM

Paper SS2-FrM10
The Adsorption and Decomposition of Trimethylamine on Pt(111)

Friday, October 29, 1999, 11:20 am, Room 607

Session: Adsorption on Metals and Silicon
Presenter: M. Trenary, University of Illinois, Chicago
Authors: D.-H. Kang, University of Illinois, Chicago
M. Trenary, University of Illinois, Chicago
Correspondent: Click to Email
Reflection absorption infrared spectroscopy (RAIRS) and temperature programmed reaction spectroscopy (TPRS) have been used to study the adsorption and decomposition of trimethylamine on Pt(111). In a series of previous RAIRS studies, it was shown that several different molecules containing CN bonds all rearranged on Pt(111) to form the same stable intermediate, aminomethylidyne, CNH@sub 2@. Aminomethylidyne was formed following the initial adsorption of azomethane, methylamine, hydrogen cyanide, and from the hydrogenation of surface CN that was produced from the dissociative adsorption of cyanogen. Furthermore, the hydrogenation of undissociated cyanogen was found to form the H@sub 2@NCCNH@sub 2@ species, which contains the same aminocarbyne functionality as in aminomethylidyne. This suggests that aminocarbynes of the general formula CNRR', where R and R' can be H or an alkyl group, may be common intermediates in surface chemical reactions involving CN-containing molecules. Dimethylaminocarbyne (CN(CH@sub 3@)@sub 2@) is a well-known ligand in the organometallic literature. It could be formed on the Pt(111) surface through the removal of the three H atoms from one of the methyl groups of trimethylamine. The RAIRS and TPRS data obtained so far support the formation of dimethylaminocarbyne as a stable intermediate species formed from the partial dehydrogenation of trimethylamine on Pt(111). A key spectroscopic feature of CN(CH@sub 3@)@sub 2@ is an intense RAIRS band at 1471 cm@super -1@, which is characteristic of the CN stretch in aminocarbynes.