In chemistry, a hydride is formally the anion of hydrogen, H−. The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed.
Silane is an inorganic compound with chemical formula, SiH4. It is a colourless, pyrophoric, toxic gas with a sharp, repulsive smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental silicon. Silane with alkyl groups are effective water repellents for mineral surfaces such as concrete and masonry. Silanes with both organic and inorganic attachments are used as coupling agents.
A silanol is a functional group in silicon chemistry with the connectivity Si–O–H. It is related to the hydroxy functional group (C–O–H) found in all alcohols. Silanols are often invoked as intermediates in organosilicon chemistry and silicate mineralogy. If a silanol contains one or more organic residue, it is an organosilanol.
Silicon tetrachloride or tetrachlorosilane is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications.
A trimethylsilyl group (abbreviated TMS) is a functional group in organic chemistry. This group consists of three methyl groups bonded to a silicon atom [−Si(CH3)3], which is in turn bonded to the rest of a molecule. This structural group is characterized by chemical inertness and a large molecular volume, which makes it useful in a number of applications.
Chlorosilanes are a group of reactive, chlorine-containing chemical compounds, related to silane and used in many chemical processes. Each such chemical has at least one silicon-chlorine bond. Trichlorosilane is produced on the largest scale. The parent chlorosilane is silicon tetrachloride.
Chloroplatinic acid (also known as hexachloroplatinic acid) is an inorganic compound with the formula [H3O]2[PtCl6](H2O)x (0 ≤ x ≤ 6). A red solid, it is an important commercial source of platinum, usually as an aqueous solution. Although often written in shorthand as H2PtCl6, it is the hydronium (H3O+) salt of the hexachloroplatinate anion (PtCl2−
6). Hexachloroplatinic acid is highly hygroscopic.
Organosilicon compounds are organometallic compounds containing carbon–silicon bonds. Organosilicon chemistry is the corresponding science of their preparation and properties. Most organosilicon compounds are similar to the ordinary organic compounds, being colourless, flammable, hydrophobic, and stable to air. Silicon carbide is an inorganic compound.
Silanes are saturated chemical compounds with the empirical formula SixHy. They are hydrosilanes, a class of compounds that includes compounds with Si-H and other Si-X bonds. All contain tetrahedral silicon and terminal hydrides. They only have Si–H and Si–Si single bonds. The bond lengths are 146.0 pm for a Si–H bond and 233 pm for a Si–Si bond. The structures of the silanes are analogues of the alkanes, starting with silane, SiH
4, the analogue of methane, continuing with disilane Si
2H
6, the analogue of ethane, etc. They are mainly of theoretical or academic interest.
Hydrosilylation, also called catalytic hydrosilation, describes the addition of Si-H bonds across unsaturated bonds. Ordinarily the reaction is conducted catalytically and usually the substrates are unsaturated organic compounds. Alkenes and alkynes give alkyl and vinyl silanes; aldehydes and ketones give silyl ethers. Hydrosilylation has been called the "most important application of platinum in homogeneous catalysis."
Reductions with hydrosilanes are methods used for hydrogenations and hydrogenolysis of organic compounds. The approach is a subset of Ionic hydrogenations. In this particular method, the substrate is treated with a hydrosilane and auxiliary reagent, often a strong acid, resulting in formal transfer of hydride from silicon to carbon. This style of reduction with hydrosilanes enjoys diverse if specialized applications.
Polysilicon hydrides are polymers containing only silicon and hydrogen. They have the formula where 0.2 ≤ n ≤ 2.5 and x is the number of monomer units. The polysilicon hydrides are generally colorless or pale-yellow/ocher powders that are easily hydrolyzed and ignite readily in air. The surfaces of silicon prepared by MOCVD using silane (SiH4) consist of a polysilicon hydride.
The dehydrogenative coupling of silanes is a reaction type for the formation of Si-Si bonds. Although never commercialized, the reaction has been demonstrated for the synthesis of certain disilanes as well as polysilanes. These reactions generally require catalysts.
Ionic Hydrogenation refers to hydrogenation achieved by the addition of a hydride to substrate that has been activated by an electrophile. Some ionic hydrogenations entail addition of H2 to the substrate and some entail replacement of a heteroatom with hydride. Traditionally, the method was developed for acid-induced reductions with hydrosilanes. Alternatively ionic hydrogenation can be achieved using H2. Ionic hydrogenation is employed when the substrate can produce a stable carbonium ion. Polar double bonds are favored substrates.
The Mukaiyama hydration is an organic reaction involving formal addition of an equivalent of water across an olefin by the action of catalytic bis(acetylacetonato)cobalt(II) complex, phenylsilane and atmospheric oxygen to produce an alcohol with Markovnikov selectivity.
Tris(trimethylsilyl)silane is the organosilicon compound with the formula (Me3Si)3SiH (where Me = CH3). It is a colorless liquid that is classified as a hydrosilane since it contains an Si-H bond. The compound is notable as having a weak Si-H bond, with a bond dissociation energy estimated at 84 kcal/mol. For comparison, the Si-H bond in trimethylsilane is 94 kcal/mol. With such a weak bond, the compound is used as a reagent to deliver hydrogen atoms. The compound has been described as an environmentally benign analogue of tributyltin hydride.
Silanes refers to diverse kinds of charge-neutral silicon compounds with the formula SiR4. The R substituents can any combination of organic or inorganic groups. Most silanes contain Si-C bonds, and are discussed under organosilicon compounds.
Transition metal silane complexes are coordination compounds containing hydrosilane ligands. An early example is (MeC5H4)Mn(CO)2(η2-HSiPh3) (Ph = C6H5).
In chemistry, transition metal silyl complexes describe coordination complexes in which a transition metal is bonded to an anionic silyl ligand, forming a metal-silicon sigma bond. This class of complexes are numerous and some are technologically significant as intermediates in hydrosilylation.
A silanide is a chemical compound containing an anionic silicon(IV) centre, the parent ion being SiH−3. The hydrogen atoms can also be substituted to produced more complex derivative anions such as tris(trimethylsilyl)silanide (hypersilyl), tris(tert-butyl)silanide, tris(pentafluoroethyl)silanide, or triphenylsilanide. The simple silanide ion can also be called trihydridosilanide or silyl hydride.
