A. Horn et al., A DIMERIZATION REACTION INDUCED BY HYDROGEN-ATOMS - FROM B(CH3)(3) ADSORBED ON C PT(100) TO B2H2(CH3)(4)/, Surface science, 414(1-2), 1998, pp. 290-297
Monolayers of trimethylborane, B(CH3)(3), were prepared on graphite-mo
nolayer-covered Pt(100) surfaces. The interaction of gaseous hydrogen
atoms with these monolayers was investigated by thermal desorption and
high-resolution electron energy-loss spectroscopies. At 80 K substrat
e temperature, tetramethyldiborane, B2H2(CH3)(4), was observed as an a
dsorbed reaction product. The reaction cross-section of 0.4 Angstrom(2
) is compatible with a direct, Eley-Rideal type reaction mechanism. Fr
om similar experiments with deuterium atoms it is apparent that H/D ex
change at the methyl groups through a sequence of abstraction and addi
tion also occurs, although with a smaller cross-section. The reaction
pathway to tetramethyldiborane involves dimerization of a BH(CH3)(2) i
ntermediate. Three possibilities for the reaction pathway to this inte
rmediate are discussed. (C) 1995 Elsevier Science B.V. All rights rese
rved.