title: Multifunctional silicon surfaces: reaction of dichlorocarbene generated from Seyferth reagent with hydrogen-terminated silicon (111) surfaces.
abstract: Insertion of dichlorocarbene (:CCl2), generated by decomposition of the Seyferth reagent PhHgCCl2Br, into the Si-H bond of a tertiary silane to form a Si-CCl2H group is an efficient homogeneous, molecular transformation. A heterogeneous version of this reaction, between PhHgCCl2Br and a silicon (111) surface terminated by tertiary Si-H bonds, was studied using a combination of surface-sensitive infrared and X-ray photoelectron spectroscopies. The insertion of dichlorocarbene into surface Si-H bonds parallels the corresponding reaction of silanes in solution, to produce surface-bound dichloromethyl groups (Si-CCl2H) covering ∼25% of the silicon surface sites. A significant fraction of the remaining Si-H bonds on the surface was converted to Si-Cl/Br groups during the same reaction, with PhHgCCl2Br serving as a halogen atom source. The presence of two distinct environments for the chlorine atoms (Si-CCl2H and Si-Cl) and one type of bromine atom (Si-Br) was confirmed by Cl 2p, Br 3d, and C 1s X-ray photoelectron spectroscopy. The formation of reactive, halogen-terminated atop silicon sites was also verified by reaction with sodium azide or the Grignard reagent (CH3MgBr), to produce Si-N3 or Si-Me functionalities, respectively. Thus, reaction of a hydrogen-terminated silicon (111) surface with PhHgCCl2Br provides a facile route to multifunctional surfaces possessing both stable silicon-carbon and labile silicon-halogen sites, in a single pot synthesis. The reactive silicon-halogen groups can be utilized for subsequent transformations and, potentially, the construction of more complex organic-silicon hybrid systems.
authors: Joint Center for Artificial Photosynthesis, ‡Materials Sciences Division, §Physical Biosciences Division, and ∥Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors: Wenjun
authors: W
authors: Liu
authors: Ian D
authors: ID
authors: Sharp
authors: T Don
authors: TD
authors: Tilley
mesh_terms: D006843:Hydrocarbons, Chlorinated / Q000138:chemical synthesis* / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D007202:Indicators and Reagents / Q000737:chemistry*; D015394:Molecular Structure; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D006843:Hydrocarbons, Chlorinated; D007202:Indicators and Reagents; D006859:Hydrogen; C004260:dichlorocarbene; D012825:Silicon