Theoretical study of initial adsorptions and subsequent surface rearrangements of H-C≡C-OH on Si(100)-2 × 1 surface

The surface adsorption reactions of hydroxyl acetylene (H-C≡C-OH) on Si(100)-2 × 1 surface were theoretically investigated with the help of CASSCF and MRMP2 theories. In addition to the well-established [2 + 2] cycloaddition of acetylene, O-H, C-O, and C-H bond cleavage reactions were found, demonstrating that acid-base type reactions of acetylene are important. The OH substitution opens two subsequent surface isomerization channels from the [2 + 2] cycloaddition product, which yield both kinetically as well as thermodynamically the most favorable surface ketene product. Consequently, the major surface product of hydroxyl acetylene is predicted to be the surface ketene rather than the expected [2 + 2] product.