Silanone

{{short description|Silicon analogue of a ketone}} thumb|right|The general structure of a silanone A '''silanone''' in chemistry is the silicon analogue of a ketone. The general description for this class of organic compounds is R₁R₂Si=O, with silicon connected to a terminal oxygen atom via a double bond and also with two organic residues (R).<ref name="Sen">{{ cite journal | title = A Stable Silanone with a Three-Coordinate Silicon Atom: A Century-Long Wait is Over | first1 = S. S. | last1 = Sen | journal = Angew. Chem. Int. Ed. | year = 2014 | volume = 53 | issue = 34 | pages = 8820–8822 | doi = 10.1002/anie.201404793 | pmid = 24990653 }}</ref> Silanones are extremely reactive<ref name="Sen" /> and until 2013 were only detected by argon matrix isolation<ref name=Arrington>''On the proposed thermal interconversion of matrix-isolated dimethylsilylene and 1-methylsilene: their reactions with oxygen atom donors'' Charles A. Arrington, Robert West, Josef Michl J. Am. Chem. Soc., '''1983''', 105 (19), pp 6176–6177 {{doi|10.1021/ja00357a048}}</ref><ref name=Withnall>''Infrared spectroscopic evidence for silicon-oxygen double bonds: silanone and the silanoic and silicic acid molecules'' Robert Withnall, Lester Andrews J. Am. Chem. Soc., '''1985''', 107 (8), pp 2567–2568 {{doi|10.1021/ja00294a070}}</ref> or in the gas phase<ref name=Bogey>{{cite journal| journal=J. Mol. Spectrosc.|volume=175|issue=2|year=1996|pages = 421–428|title=Experimentally Determined Structure of H₂SiO by Rotational Spectroscopy and Isotopic Substitution|author1=M. Bogey |author2=B. Delcroix |author3=A. Walters |author4=J-C Guillemin |doi= 10.1006/jmsp.1996.0048|bibcode = 1996JMoSp.175..421B }}</ref> but not isolated. A synthesis of a stable silanone was reported in 2014. Silanones are of some interest to academic research, with their reactivity being of some relevance to the double bond rule.

Silanones are unstable and favor oligomerisation to siloxanes. The reason for this instability is the weak pi bond with a small HOMO–LUMO gap caused by an unfavorable overlap between the p-orbitals of silicon and oxygen. A second reason for the observed instability is the strongly polarized silicon–oxygen bond, Si^δ+–O^δ−.<ref name="Sen" />

==History== The first to postulate a silanone were Kipping & Lloyd in 1901,<ref name=Kipping>''XLVII.—Organic derivatives of silicon. Triphenylsilicol and alkyloxysilicon chlorides'' F. Stanley Kipping, Ph.D., D.Sc., F.R.S. and Lorenzo L. Lloyd J. Chem. Soc., Trans., 1901,79, 449-459 {{doi|10.1039/CT9017900449}}</ref> but their products were in fact siloxanes. It was not until 2014 that a stable silanone was reported.<ref name=Filippou>Filippou, A. C., Baars, B., Chernov, O., Lebedev, Y. N. and Schnakenburg, G. (2014), ''Silicon–Oxygen Double Bonds: A Stable Silanone with a Trigonal-Planar Coordinated Silicon Center.'' Angew. Chem. Int. Ed., 53: 565–570. {{doi|10.1002/anie.201308433}}</ref> In this compound, silicon is bonded to a SIDipp (1,3-bis(2,6-iPr₂-C₆H₃)imidazolidin-2-ylidene) group and a (Cp^*)Cr(CO)₃ group. Its stability is owed to the direct coordination of silicon to chromium and to steric shielding. The reported Si=O bond length is 1.526 Å, in line with expectations. It has been described as a cationic metallosilanone.<ref name=Sen />

Other strategies have recently been used to stabilise silanones,<ref>{{ cite journal | title = Chemical Tricks To Stabilize Silanones and Their Heavier Homologues with EO Bonds (E=Si–Pb): From Elusive Species to Isolable Building Blocks | first1 = Y. | last1 = Xiong | first2 = S. | last2 = Yao | first3 = M. | last3 = Driess | journal = Angew. Chem. Int. Ed. | year = 2013 | volume = 52 | issue = 16 | pages = 4302–4311 | doi = 10.1002/anie.201209766 | pmid = 23450830 | bibcode = 2013ACIE...52.4302X }}{{clarify|reason=what is the unicode private-use character (U+F8FE) in title= supposed to be?|date=October 2025}}</ref> for example coordination to Lewis acids or bases<ref>{{ cite journal | first1 = T. | last1 = Sun | first2 = J. | last2 = Li | first3 = H. | last3 = Wang | title = Recent Advances in the Chemistry of Heavier Group 14 Analogues of Carbonyls | journal = Chem. Asian J. | year = 2022 | volume = 17 | issue = 18 |article-number=e202200611 | doi = 10.1002/asia.202200611 | pmid = 35883252 | s2cid = 251104394 }}</ref> and steric shielding.<ref>{{ cite journal | title = An Isolable Silicon Analogue of a Ketone that Contains an Unperturbed Si=O Double Bond | first1 = Ryo | last1 = Kobayashi | first2 = Shintaro | last2 = Ishida | first3 = Takeaki | last3 = Iwamoto | journal = Angew. Chem. Int. Ed. | volume = 58 | issue = 28 | year = 2019 | pages = 9425–9428 | doi = 10.1002/anie.201905198 | pmid = 31095845 | bibcode = 2019ACIE...58.9425K | s2cid = 157056381 | doi-access = free }}</ref>

==References== {{reflist}}

Category:Organosilicon compounds