Monolayers of 1-alkynes on the H-terminated Si(100) surface

Monolayers of a series of l-alkynes, from 1-dodecyne to 1-octadecyne, have been prepared on the hydrogen-terminated Si(100) Surface via a thermal reac tion of the organic compound with this Si surface. An efficient procedure i s presented for the synthesis of l-alkynes from the corresponding l-alkenes . The resulting monolayers were characterized by water contact angle measur ements, ATR infrared spectroscopy, and X-ray reflectivity. The results show that these l-alkynes give well-ordered, covalently bonded monolayers, whic h are at least as ordered as those of the corresponding l-alkenes. The exac t binding geometry of the I-alkyne to the Si surface was investigated. The results from IR spectroscopy and X-ray reflectivity measurements indicate t hat the I-alkynes form two Si-C bonds to the surface per reacting molecule. Quantum mechanical calculations confirm that this formation of two Si-C bo nds is not only chemically possible but also energetically much more favora ble than formation of only one Si-C bond per reacting molecule.