Siloxides are
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one ele ...
s with the formula R
3SiOM, where R is usually an organic group and M is usually a
metal
A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typi ...
cation
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
. Also called silanoates, they are derived by
deprotonation
Deprotonation (or dehydronation) is the removal (transfer) of a proton (or hydron, or hydrogen cation), (H+) from a Brønsted–Lowry acid in an acid–base reaction.Henry Jakubowski, Biochemistry Online Chapter 2A3, https://employees.csbsju. ...
of
silanols. They also arise by the degradation of
siloxanes by base:
[
:R3SiOSiR3 + 2 NaOH → 2 R3SiONa + H2O
Cleavage of cyclic siloxanes affords siloxides:
:(Me2SiO)3 + MeLi → Me3SiOSiMe2OSiMe2OLi
These anions function as ]ligand
In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ele ...
s for metal ions, forming complexes similar to metal alkoxides. Sodium trimethylsiloxide is useful for generating metal complexes by salt metathesis reactions. A very bulky siloxide is tert-butyl
In organic chemistry, butyl is a four-carbon alkyl radical or substituent group with general chemical formula , derived from either of the two isomers (''n''-butane and isobutane) of butane.
The isomer ''n''-butane can connect in two ways, giv ...
3SiO−, sometimes called silox.
Siloxides are weaker net donors than alkoxides because pπ-d donation has to compete with backbonding from the oxygen atom into the low-lying Si-C σ* orbitals.[{{cite journal , last1=Krempner , first1=Clemens , title=Role of Siloxides in Transition Metal Chemistry and Homogeneous Catalysis , journal=Eur. J. Inorg. Chem. , year=2011 , volume=2011 , issue=11 , page=1689 , doi=10.1002/ejic.201100044 , url=https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejic.201100044]
References
Organosilicon compounds