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Revision as of 14:06, 6 December 2011 editBeetstra (talk | contribs)Edit filter managers, Administrators172,084 edits Saving copy of the {{chembox}} taken from revid 433221716 of page Silabenzene for the Chem/Drugbox validation project (updated: 'CASNo').		Latest revision as of 02:29, 13 November 2024 edit Bernanke's Crossbow (talk | contribs)Extended confirmed users7,929 edits →Synthesis: fix linebreaks
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	{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}}
	{{Chembox		{{Chembox
			|Verifiedfields = changed
⚫	| verifiedrevid = 397460160
			|Watchedfields = changed
⚫	| ImageFile = Silabenzene.svg
		⚫	|verifiedrevid = 464390098
	| ImageSize = 120px
		⚫	|ImageFileL1 = Silabenzene.svg
⚫	| ImageName = Structural formula of silabenzene
			|ImageSizeL1 = 85
	| PIN = Silabenzene
		⚫	|ImageAltL1 = Structural formula of silabenzene
	| SystematicName = Siline
			|ImageFileR1 = Silabenzene-3D-balls.png
⚫	| Section1 = {{Chembox Identifiers
			|ImageSizeR1 = 145
	| CASNo = <!-- blanked - oldvalue: 289-77-0 -->
			|ImageAltR1 = Ball-and-stick model of the Silabenzene molecule
⚫	| CASNo_Ref = {{cascite|correct|??}}
			|PIN = Siline<ref name=iupac2013>{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = ] | date = 2014 | location = Cambridge | page = 392 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4}}</ref>
⚫	| PubChem = 136138
			|OtherNames =
	| PubChem_Ref = {{Pubchemcite|correct|PubChem}}
		⚫	|Section1={{Chembox Identifiers
⚫	| ChemSpiderID = 119915
			|CASNo = 289-77-0
⚫	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
		⚫	|CASNo_Ref = {{cascite|correct|PubChem}}
⚫	| SMILES = C1=CC=C=C1
		⚫	|PubChem = 136138
	| SMILES1 = c1cccc1
		⚫	|ChemSpiderID = 119915
⚫	| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
		⚫	|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
⚫	| StdInChI = 1S/C5H6Si/c1-2-4-6-5-3-1/h1-6H
		⚫	|SMILES = C1=CC=C=C1
⚫	| InChI = 1/C5H6Si/c1-2-4-6-5-3-1/h1-6H
	| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}		|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
		⚫	|StdInChI = 1S/C5H6Si/c1-2-4-6-5-3-1/h1-6H
⚫	| StdInChIKey = YJHHPIHPAJYNFT-UHFFFAOYSA-N
		⚫	|InChI = 1/C5H6Si/c1-2-4-6-5-3-1/h1-6H
⚫	| InChIKey = YJHHPIHPAJYNFT-UHFFFAOYAP}}
		⚫	|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
⚫	| Section2 = {{Chembox Properties
		⚫	|StdInChIKey = YJHHPIHPAJYNFT-UHFFFAOYSA-N
	| C = 5
		⚫	|InChIKey = YJHHPIHPAJYNFT-UHFFFAOYAP}}
	| H = 6
		⚫	|Section2={{Chembox Properties
	| Si = 1
			|C=5 | H=6 | Si=1
	| ExactMass = 94.023876725 g mol<sup>-1</sup>}}
	}}		}}}}
			]
			A '''silabenzene''' is a ] compound containing one or more ] atoms instead of ] atoms in ]. A single substitution gives silabenzene proper; additional substitutions give a '''disilabenzene''' (3 theoretical isomers), '''trisilabenzene''' (3 isomers), etc.
			Silabenzenes have been the targets of many theoretical and synthetic studies by ] interested in the question of whether analogs of ] with Group IV elements heavier than carbon, e.g., silabenzene, ] and ]—so-called "heavy benzenes"—exhibit ]ity.
			Although several ] compounds bearing ], ], and ] atoms have been known since the early stages of ], silabenzene had been considered to be a transient, un-isolable compound and was detected only in low-temperature matrices or as its ] adduct for a long time. In recent years, however, a ] silabenzene and other heavy ] compounds with ] or ] atoms have been reported.
			==Synthesis==
			]
			Several attempts to synthesize stable silabenzenes have been reported from the late 1970s using well-known bulky substituents such as a ] (1,1-dimethylethyl) or a TMS (]) group, but such silabenzenes readily react with themselves to give the corresponding ] even at low temperature (below -100]) due to the high reactivity of ]-] ''π'' bonds. In 1978 Barton and Burns reported that flow pyrolysis of 1{{nbh}}methyl-1{{nbh}}allyl-1{{nbh}}silacyclohexa-2,4{{nbh}}diene through a quartz tube heated to 428&nbsp;°C using either ethyne or perfluoro-2-butyne as both a reactant and a carrier gas afforded the methyl-1{{nbh}}silylbenzene Diel-Alder adducts, 1{{nbh}}methyl-1{{nbh}}sila&shy;bicyclo&shy;octatriene or 1{{nbh}}methyl-2,3{{nbh}}bis(trifluoromethyl)-1{{nbh}}sila&shy;bicyclo&shy;octatriene, respectively, by way of a retro-].<ref>{{Cite journal | last1 = Barton | first1 = T. J. | last2 = Burns | first2 = G. T. | doi = 10.1021/ja00484a075 | title = Unambiguous generation and trapping of a silabenzene | journal = Journal of the American Chemical Society | volume = 100 | issue = 16 | pages = 5246 | year = 1978}}</ref>
			A computational investigation in 2013 points out a new route to stable silabenzenes at ambient conditions through ].<ref>{{cite journal|last1=Rouf|first1=Alvi Muhammad|last2=Jahn|first2=Burkhard O.|last3=Ottosson|first3=Henrik|title=Computational Investigation of Brook-Type Silabenzenes and Their Possible Formation through -Si→O Silyl Shifts|journal=Organometallics|date=14 January 2013|volume=32|issue=1|pages=16–28|doi=10.1021/om300023s}}</ref> The -Si → O shift of TMS or ] (TIPS) substituted precursors with tetrahedral silicon atoms to an adjacent carbonyl oxygen lead to aromatic Brook-type silabenzenes.
			Following the synthesis of the ] analog 2-silanaphthalene,<ref>{{Cite journal| doi = 10.1021/ja9710924| title = A Stable Neutral Silaaromatic Compound, 2-{2,4,6-Trisphenyl}- 2-Silanaphthalene| year = 1997| last1 = Tokitoh | first1 = N.| last2 = Wakita | first2 = K.| last3 = Okazaki | first3 = R.| last4 = Nagase | first4 = S.| last5 = von Ragué Schleyer | first5 = P.| last6 = Jiao | first6 = H.| journal = Journal of the American Chemical Society| volume = 119| issue = 29| pages = 6951–6952}}</ref><ref>{{Cite journal| last1 = Wakita | first1 = K. | last2 = Tokitoh | first2 = N. | last3 = Okazaki | first3 = R. | last4 = Nagase | first4 = S. | last5 = von Ragué Schleyer | first5 = P. | last6 = Jiao | first6 = H. | title = Synthesis of Stable 2-Silanaphthalenes and Their Aromaticity | journal = Journal of the American Chemical Society| year = 1999 | volume = 121| issue = 49| pages = 11336–11344 | doi = 10.1021/ja992024f}}</ref> the first sila-aromatic compound, by Norihiro Tokitoh and Renji Okazaki in 1997, the same group reported thermally stable silabenzene in 2000 taking advantage of a new ] ].<ref>{{Cite journal| doi = 10.1021/ja000309i| title = Crystal Structure of a Stable Silabenzene and Its Photochemical Valence Isomerization into the Corresponding Silabenzvalene| year = 2000| last1 = Wakita | first1 = K.| last2 = Tokitoh | first2 = N.| last3 = Okazaki | first3 = R.| last4 = Takagi | first4 = N.| last5 = Nagase | first5 = S.| journal = Journal of the American Chemical Society| volume = 122| issue = 23| pages = 5648–5649 }}</ref> A 9-sila] derivative has been reported in 2002,<ref>{{Cite journal| doi = 10.1021/om0108301| title = The First Stable 9-Silaanthracene| year = 2002| last1 = Takeda | first1 = N.| last2 = Shinohara | first2 = A.| last3 = Tokitoh | first3 = N.| journal = Organometallics| volume = 21| issue = 2| pages = 256–258}}</ref> a 1-silanaphthalene also in 2002.<ref>{{Cite journal| doi = 10.1021/om0205041| title = Synthesis and Properties of the First 1-Silanaphthalene| year = 2002| last1 = Takeda | first1 = N. | last2 = Shinohara | first2 = A. | last3 = Tokitoh | first3 = N. | journal = Organometallics| volume = 21| issue = 20| pages = 4024–4026}}</ref>
			A 1,4-disilabenzene was reported in 2002.<ref>{{Cite journal| doi = 10.1021/ja9930061| title = 1,4-Disila(Dewar-benzene) and 1,4-Disilabenzene: Valence Isomerization of Bis(alkylsilacyclopropenyl)s| year = 2000| last1 = Kabe | first1 = Y. | last2 = Ohkubo | first2 = K. | last3 = Ishikawa | first3 = H. | last4 = Ando | first4 = W. | journal = Journal of the American Chemical Society| volume = 122| issue = 15| pages = 3775–3776 }}</ref> In 2007, 1,2-disilabenzene was synthesized via formal ] of a ] (Si-Si triple bonded species) and ].<ref>{{Cite journal| doi = 10.1021/ja072759h| pmid = 17542592| year = 2007| last1 = Kinjo | first1 = R.| last2 = Ichinohe | first2 = M.| last3 = Sekiguchi | first3 = A.| last4 = Takagi | first4 = N.| last5 = Sumimoto | first5 = M.| last6 = Nagase | first6 = S.| title = Reactivity of a Disilyne RSi≡SiR (R=Si<sup>j</sup>Pr(CH(SiMe<sub>3</sub>)<sub>2</sub>)<sub>2</sub>) Toward π-Bonds: Stereospecific Addition and a New Route to an Isolable 1,2-Disilabenzene| volume = 129| issue = 25| pages = 7766–7767| journal = Journal of the American Chemical Society }}</ref>
			Some theoretical studies suggest that the symmetric 1,3,5-trisilabenzene may be more stable than 1,2-disilabenzene.<ref>{{Cite journal| doi = 10.1021/om9903745| title = The Silabenzenes: Structure, Properties, and Aromaticity| year = 2000| last1 = Baldridge | first1 = K. K.| last2 = Uzan | first2 = O.| last3 = Martin | first3 = J. M. L.| journal = Organometallics| volume = 19| issue = 8| pages = 1477–1487 }}</ref>
			==Properties and reactions==
			Isolated silabenzene reacts with various reagents at 1,2- or 1,4-positions to give ]-type products, so the ]ity of the silabenzene is destroyed. It is different from ], which reacts with ]s to give not ]s but substituted benzenes, so benzene sustains its ]ity. ] is a ] ], so the Si-C ''π'' bond in the silabenzene is highly ] and easily broken. The silabenzene is also light-sensitive; ] irradiation gives the ], a silabenzvalene. The theoretical calculations and the ] ]s of silabenzenes, though, show that silabenzene is an ] compound in spite of the different reactivity from ] and other classical aromatic compounds.
			==Hexasilabenzene==
			In calculations the all-silicon hexasilabenzene Si<sub>6</sub>H<sub>6</sub> is predicted to have 6-fold symmetry <ref>{{Cite journal| doi = 10.1021/ja00839a005| title = Ground States of Molecules. XXIX. MINDO/3 Calculations of Compounds Containing Third Row Elements| year = 1975| last1 = Dewar | first1 = M. J. S.| last2 = Lo | first2 = D. H.| last3 = Ramsden | first3 = C. A.| journal = Journal of the American Chemical Society| volume = 97| issue = 6| pages = 1311–1318}}</ref> or a ].<ref>{{Cite journal| doi = 10.1063/1.452726| title = Hexasilabenzene (Si<sub>6</sub>H<sub>6</sub>). Is the Benzene-Like D<sub>6h</sub> Structure Stable?| year = 1987| last1 = Nagase | first1 = S.| last2 = Teramae | first2 = H.| last3 = Kudo | first3 = T.| journal = The Journal of Chemical Physics| volume = 86| issue = 8| pages = 4513–4517 | bibcode = 1987JChPh..86.4513N}}</ref> It was shown that the deviation from planarity in hexasilabenzene is caused by the ].<ref>{{cite journal|last=Ivanov|first=A.|author2=Boldyrev. A |title=Si<sub>6−n</sub>C<sub>n</sub>H<sub>6</sub> (n = 0-6) Series: When Do Silabenzenes Become Planar and Global Minima?|journal=J. Phys. Chem. A|volume=116|issue=38|pages=9591–9598|year=2012|doi=10.1021/jp307722q|pmid=22946702|bibcode=2012JPCA..116.9591I}}</ref> A stable hexasilaprismane has been known since 1993 <ref>{{Cite journal| doi = 10.1021/ja00066a075| title = Chemistry of Organosilicon Compounds. 303. The "Missing" Hexasilaprismane: Synthesis, X-Ray Analysis and Photochemical Reactions| year = 1993| last1 = Sekiguchi | first1 = A.| last2 = Yatabe | first2 = T.| last3 = Kabuto | first3 = C.| last4 = Sakurai | first4 = H.| journal = Journal of the American Chemical Society| volume = 115| issue = 13| pages = 5853–5854 }}</ref> A compound isomeric with hexasilabenzene was first reported in 2010.<ref>{{Cite journal| doi = 10.1126/science.1181771| pmid = 20110501| year = 2010| last1 = Abersfelder | first1 = K.| last2 = White| first2 = A.| last3 = Rzepa | first3 = H.| last4 = Scheschkewitz | first4 = D.| title = A Tricyclic Aromatic Isomer of Hexasilabenzene| volume = 327| issue = 5965| pages = 564–566| journal = Science | bibcode = 2010Sci...327..564A | s2cid = 206523406}}</ref> This compound is reported as stable and with according to ] a chairlike tricyclic silicon frame.
			]
			The searching of a planar Si<sub>6</sub> analogue to benzene has been extended to anionic cycles and structures bearing lithium atoms replacing hydrogens.<ref>{{cite journal|last1=Takahasi|first1=M|last2=Kawazoe|first2=Y|title=Theoretical Study on Planar Anionic Polysilicon Chains and Cyclic Si<sub>6</sub>H Anions with D<sub>6h</sub> Symmetry|journal=Organometallics|date=2005|volume=24|issue=10|pages=2433–2440|doi=10.1021/om050025c}}</ref> Through ] calculations, it has been shown that from a series of planar and tridimensional structures with molecular formula Si<sub>6</sub>Li<sub>2-8</sub>, the global minimum is a Si<sub>6</sub>Li<sub>6</sub> planar ring. This particular ring has D<sub>2h</sub> symmetry with 4 lithium cations placed between two adjacent silicon atoms –forming ]s –and two more Li cations located above and below the center of the ring’s plane. A highly symmetric D<sub>6h</sub> structure analogue to hexalithiumbenzene<ref>{{cite journal|last1=Xie|first1=Y|last2=Schaefer|first2=H|title=Hexalithiobenzene: a D<sub>6h</sub> Equilibrium Geometry with Six Lithium Atoms in Bridging Positions|journal=Chemical Physics Letters|date=1991|volume=179|issue=5,6|pages=563–567|doi=10.1016/0009-2614(91)87104-J|bibcode=1991CPL...179..563X}}</ref> was found to be higher in energy by 2.04 eV to respect to the minimum.<ref>{{cite journal|last1=Zdetsis|first1=A|title=Stabilization of Flat Aromatic Si 6 Rings Analogous to Benzene: Ab initio Theoretical Prediction|journal=The Journal of Chemical Physics|date=2007|volume=127|issue=21|page=214306|doi=10.1063/1.2805366|pmid=18067356|bibcode=2007JChPh.127u4306Z}}</ref><br />
			] was also tested using density functional calculations. DFT can be effectively used to calculate the aromaticity of various molecular systems<ref>{{cite journal|last1=De Proft|first1=F|last2=Geerlings|first2=P|title=Conceptual and Computational DFT in the Study of Aromaticity|journal=Chemical Reviews|date=2001|volume=101|issue=5|pages=1451–1464|doi=10.1021/cr9903205|pmid=11710228}}</ref> using the B3LYP hybrid density functional; this method has been proved to be the method of choice for computing delocalized systems.<ref>{{cite journal|last1=Nedel|first1=M|last2=Houk|first2=K|last3=Tolbert|first3=L|last4=Vogel|first4=E|last5=Jiao|first5=H|last6=von Rague Schleyer|first6=P|title=Bond Alternation and Aromatic Character in Cyclic Polyenes: Assessment of Theoretical Methods for Computing the Structures and Energies of Bismethanoannulenes|journal=The Journal of Physical Chemistry A|date=1998|volume=102|issue=36|pages=7191–7198|doi=10.1021/jp9820976|bibcode=1998JPCA..102.7191N}}</ref> The ]s (NICS)<ref>{{cite journal|last1=von Rague Schleyer|first1=P|last2=Maerker|first2=C|last3=Dransfeld|first3=A|last4=Jiao|first4=H|last5=van Eikema Hommes|first5=N|title=Nucleus-Independent Chemical Shifts: A Simple and Efficient Aromaticity Probe|journal=Journal of the American Chemical Society|date=1996|volume=118|issue=26|pages=6317–6318|doi=10.1021/ja960582d|pmid=28872872|s2cid=207152799}}</ref> was selected as the quantitative criterion to evaluate the aromatic character of the structures under study. The global minimum (D<sub>2h</sub> symmetry ring) and the D<sub>6h</sub> symmetry ring show values of −3.95 and −5.95, respectively. In NICS calculations, negative values indicate aromaticity.<br />
			More recently, using a novel ], a Si<sub>6</sub>Li<sub>6</sub> three dimensional structure has been calculated to be more stable than planar isomers.<ref>{{cite journal|last1=Santos|first1=J|last2=Contreras|first2=M|last3=Merino|first3=G|title=Structure and Stability of Si6Li6: Aromaticity vs Polarizability|journal=Chemical Physics Letters|date=2010|volume=496|issue=1–3|pages=172–174|doi=10.1016/j.cplett.2010.07.026|bibcode=2010CPL...496..172S|hdl=10533/144740|hdl-access=free}}</ref>
			== See also ==
			{{Scholia}}
			* 6-membered aromatic rings with one carbon replaced by another group: ], ], silabenzene, ], ], ], ], ], ], ], ], ], ]
			==References==
			{{reflist}}
			]
			]