On the Mechanism of Silicon Activation by Halogen Atoms

F. A .SORIA; E. M. PATRITO; P. PAREDES-OLIVERA

AMER CHEMICAL SOC

Año: 2011 vol. 27 p. 2613 - 2613

Despite the widespread use of chlorinated silicon as the starting point for further functionalization reactions, the high reactivity of this surface toward a simple polar molecule such as ammonia still remains unclear. We therefore undertook a comprehensive investigation of the factors that govern the reactivity of halogenated silicon surfaces. The reaction of NH3 was investigated comparatively on the Cl-Si(100)-2×1, Br-Si(100)-2×1, H-Si(100)-2×1, and Si(100)-2×1 surfaces using density functional theory. The halogenated surfaces show considerable activation with respect to the hydrogenated surface. The reaction on the halogenated surfaces proceeds via the formation of a stable datively bonded complex in which a silicon atom is pentacoordinated. The activation of the halogenated Si(100)-2×1 surfaces toward ammonia arises from the large redistribution of charge in the transition state that precedes the breakage of the Si-X bond and the formation of the Si-NH2 bond. This t