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Organometallic compound containing carbon–silicon bonds

Organosilicon chemistry is the study of organometallic compounds containing carbon–silicon bonds, to which they are called organosilicon compounds. Most organosilicon compounds are similar to the ordinary organic compounds, being colourless, flammable, hydrophobic, and stable to air. Silicon carbide is an inorganic compound.

In 1863 Charles Friedel and James Crafts made the first organochlorosilane compound. The same year they also described a «polysilicic acid ether» in the preparation of ethyl and methyl o silicic acid. He also had coined the term "silicone" (resembling ketones, this is erroneous though) in relation to these materials in 1904. In recognition of Kipping's achievements the Dow Chemical Company had established an award in 1960s that is given for significant contributions into the silicon chemistry. In his works Kipping was noted for using Grignard reagents to make alkylsilanes and arylsilanes and the preparation of silicone oligomers and polymers for the first time.

Organosilicon compounds are widely encountered in commercial products. Most common are antifoamers, caulks (sealant), adhesives, and coatings made from silicones. Other important uses include agricultural and plant control adjuvants commonly used in conjunction with herbicides and fungicides.

Carbon–silicon bonds are absent in biology, however enzymes have been used to artificially create carbon silicon bonds in living microbes. Silicates, on the other hand, have known existence in diatoms. Silafluofen is an organosilicon compound that functions as a pyrethroid insecticide. Several organosilicon compounds have been investigated as pharmaceuticals.

Another major method for the formation of Si C bonds is hydrosilylation (also called hydrosilation). In this process, compounds with Si H bonds (hydrosilanes) add to unsaturated substrates. Commercially, the main substrates are alkenes. Other unsaturated functional groups — alkynes, imines, ketones, and aldehydes — also participate, but these reactions are of little economic value. Hydrosilylation requires metal catalysts, especially those based on platinum group metals. In the related silylmetalation, a metal replaces the hydrogen atom.

Silicon is a component of many functional groups. Most of these are analogous to organic compounds. The overarching exception is the rarity of multiple bonds to silicon, as reflected in the double bond rule.

Organosilyl chlorides are important commodity chemicals. They are mainly used to produce silicone polymers as described above. Especially important silyl chlorides are dimethyldichlorosilane , methyltrichlorosilane , and trimethylsilyl chloride (Me3SiCl) are all produced by direct process. More specialized derivatives that find commercial applications include dichloromethylphenylsilane, trichloro(chloromethyl)silane, trichloro(dichlorophenyl)silane, trichloroethylsilane, and phenyltrichlorosilane. Although proportionately a minor outlet, organosilicon compounds are widely used in organic synthesis. Notably trimethylsilyl chloride Me3SiCl is the main silylating agent. One classic method called the Flood reaction for the synthesis of this compound class is by heating hexaalkyldisiloxanes with concentrated sulfuric acid and a sodium halide.

The silicon to hydrogen bond is longer than the C–H bond (148 compared to 105 pm) and weaker (299 compared to 338 kJ/mol). Hydrogen is more electronegative than silicon hence the naming convention of silyl hydrides. Commonly the presence of the hydride is not mentioned in the name of the compound. Triethylsilane has the formula Et3SiH. Phenylsilane is The parent compound is called silane.

Organosilicon compounds, unlike their carbon counterparts, do not have a rich double bond chemistry. Compounds with silene Si=C bonds (also known as alkylidenesilanes) are laboratory curiosities such as the silicon benzene analogue silabenzene. In 1967, Gusel'nikov and Flowers provided the first evidence for silenes from pyrolysis of dimethylsilacyclobutane. The first stable (kinetically shielded) silene was reported in 1981 by Brook. Disilenes have Si=Si double bonds and disilynes are silicon analogues of an alkyne. The first Silyne (with a silicon to carbon triple bond) was reported in 2010.

Siloles, also called silacyclopentadienes, are members of a larger class of compounds called metalloles. They are the silicon analogs of cyclopentadienes and are of current academic interest due to their electroluminescence and other electronic properties. Siloles are efficient in electron transport. They owe their low lying LUMO to a favorable interaction between the antibonding sigma silicon orbital with an antibonding pi orbital of the butadiene fragment.

Organosilicon compounds affect bee (and other insect) immune expression, making them more susceptible to viral infection.