dichlorosilanes

Dichlorosilanes are a class of organosilicon compounds in which silicon bears two chlorine substituents and two other substituents, which may be hydrogen or organic groups. The general formulas are SiH2Cl2 (the simplest member) and R2SiCl2 for dialkyl or diaryl variants. They are used as versatile building blocks in silicon chemistry and as precursors to a wide range of silicon-containing materials.

Structurally, the silicon center in dichlorosilanes is four-coordinate and tetrahedral. The Si–Cl bonds are highly polar, making the compounds reactive toward moisture and nucleophiles. Depending on the substituents, dichlorosilanes are typically colorless to pale liquids or gases with varying volatility. They are moisture-sensitive and typically handled under inert atmosphere. Upon contact with water, they hydrolyze to produce hydrochloric acid and silanols, which can further condense to form siloxane networks.

Preparation and handling methods vary, but dichlorosilanes are often generated or used in situ by partial chlorination or controlled hydrocarbon substitution of higher chlorosilanes or hydrosilanes. Due to their reactivity and corrosivity, they are stored and used with appropriate safety measures to prevent hydrolysis and exposure to moisture.

Applications center on their role as intermediates in the synthesis of higher-value organosilicon compounds and polymers. They can undergo hydrolysis and condensation to form siloxanes, contributing to the production of silicones and related materials. They also serve as precursors in chemical vapor deposition and other processes that deposit silicon-containing films. Representative members include SiH2Cl2 and dialkyl- or diaryl-dichlorosilanes such as Me2SiCl2 and Ph2SiCl2.