| 词条 | Pentamethylantimony |
| 释义 |
| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = | ImageFile = | ImageFile_Ref = | ImageSize = 244 | ImageAlt = | ImageFile1 = | ImageAlt1 = | SystematicName = pentamethyl-λ5-stibane |Section1={{Chembox Identifiers | CASNo_Ref = {{cascite|correct|??}} | CASNo = 15120-50-0 | PubChem = 123354 | ChemSpiderID = 109956 | ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} | EINECS = 239-173-4 | EC_number = 239-173-4 | MeSHName = | SMILES = C[Sb](C)(C)(C)C | StdInChI = 1S/5CH3.Sb/h5*1H3; | StdInChI_Ref = {{stdinchicite|changed|chemspider}} | StdInChIKey = BBEVMUOEYNOTTE-UHFFFAOYSA-N | StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} }} |Section2={{Chembox Properties | C=5 | Sb=1 |H=15 | Appearance = Colourless liquid | Density = | MeltingPtC = -19 | BoilingPtC = 160 }} |Section3={{Chembox Thermochemistry | DeltaHf = | DeltaHc = }} |Section8={{Chembox Related | OtherCompounds = Trimethylstibine Pentamethylarsenic Pentamethylbismuth Pentamethyltantalum Pentaphenylantimony }} }} Pentamethylantimony or pentamethylstiborane is an organometalllic compound containing five methyl groups bound to an antimony atom with formula Sb(CH3)5. It is an example of a hypervalent compound. The molecular shape is trigonal bipyramid.[1] Some other antimony(V) organometallic compounds include pentapropynylantimony (Sb(CCCH3)5) and pentaphenyl antimony (Sb(C6H5)5).[2] Other known pentamethyl-pnictides include pentamethylbismuth and pentamethylarsenic. ProductionPentamethylantimony can be made by reacting Sb(CH3)3Br2 with two equivalents of methyl lithium.[2] Another production route is to convert trimethylstibine to the trimethyl antimony dichloride, and then replace the chlorine with methyl groups with methyl lithium.[2] Sb(CH3)3 + Cl2 → Sb(CH3)3Cl2 Sb(CH3)3Cl2 + 2LiCH3 → Sb(CH3)5 + 2LiCl PropertiesPentamethylantimony is colourless.[2] At -143°V it crystallizes in the orthorhombic system with space group Ccmm. Unit cell dimensions are a=6.630 Å b=11.004 Å c=11.090 Å. There are four formula per unit cell. Unit cell volume is 809.1 Å3.[2] The trigonal bipyramid shape has three equatorial positions for carbon, and two axial positions at the peaks of the pyramids. The length of the antimony-carbon bond is around 214 pm for equatorial methyl groups and 222 pm for the axial positions. The bond angles are 120° for ∠C-Sb-C across the equator, and 90° for ∠C-Sb-C between equator and axis.[2] The molecules rapidly change carbon atom position, so that in NMR spectrum as low as −100°C, there is only one kind of hydrogen position.[3] Pentamethylantimony is more stable than pentamethylbismuth, because in lower energy trimethylbismuth, the non-bonding pair of electrons is more shielded due to the f-electrons and the lanthanoid contraction. Trimethylantimony is higher in energy, and thus less is released in a decomposition of pentamethylantimony.[2] Pentamethylantimony can be stored as a liquid in clean glass at room temperature.[10] Pentamethylantimony melts at -19°C. Although it decomposes when boiling is attempted and can explode, it has a high vapour pressure at 8 mmHg at 25°C.[4] There are two absorption bands in the ultraviolet at 2380 and 2500 Å.[4] ReactionsPentamethylantimony reacts with methyl lithium to yield a colourless lithium hexamethylantimonate in tetrahydrofuran.[2] Sb(CH3)5 + LiCH3 → Li(thf)Sb(CH3)6 Pentamethylantimony reacts with silsesquioxanes to yield tetramethylstibonium silsesquioxanes. eg (cyclo-C6H11)7Si7O9(OH)3 yields (cyclo-C6H11)7Si7O9(OSB(CH3)4)3. The reaction happens quickly when there are more than two OH groups.[5] Phosphonic acids and phosphinic acids combine with pentamethylantimony to yield compounds like (CH3)4SbOP(O)Ph2, (CH3)4SbOP(O)(OH)Ph and (CH3)4SbOP(O)(OH)3, eliminating methane.[6]Stannocene Sn(C5H5)2 combines with pentamethylantimony to produce bis(tetramethylstibonium)tetracyclopentadienylstannate ([(CH3)4Sb]2Sn(C5H5)4).[7]Pentamethylantimony reacts with many very weak acids to form a tetramethylstibonium salt or tetramethylstibonium derivative with the acid. Such acids include water (H2O), alcohols, thiols, phenol, carboxylic acids, hydrogen fluoride, thiocyanic acid, hydrazoic acid, difluorophosphoric acid, thiophosphinic acids, and alkylsilols.[8] With halogens, pentamethylantimony has one or two methyl groups replaced by the halogen atoms.[8] Lewis acids also react to form tetramethyl stibonium salts, including [(CH3)4Sb]TlBr4, [(CH3)4Sb][CH3SbCl5], [8] Pentamethylantimony reacts with the surface of silica to coat it with Si-O-Sb(CH3)4 groups. Over 250°C this decomposes to Sb(CH3) and leaves methyl groups attached to the silica surface.[9] References1. ^{{cite journal|last1=Greene|first1=Tim M.|last2=Downs|first2=Anthony J.|last3=Pulham|first3=Colin R.|last4=Haaland|first4=Arne|last5=Verne|first5=Hans Peter|last6=Volden|first6=Hans Vidar|last7=Timofeeva|first7=Tatjana V.|title=Molecular Structures of Pentamethylarsenic(V) and Trimethyldichloroarsenic(V) by Gas Electron Diffraction and ab Initio Calculations:? Molecular Mechanics Calculations on Pentamethylarsenic(V), Pentaphenylarsenic(V), and Related Compounds|journal=Organometallics|date=November 1998|volume=17|issue=24|pages=5287–5293|doi=10.1021/om980520r}} {{antimony compounds}}2. ^1 2 3 4 5 {{cite journal|last1=Wallenhauer|first1=Stephan|last2=Seppelt|first2=Konrad|title=Antimony(V) and Bismuth(V) Methyl Compounds: A Structural Comparison|journal=Inorganic Chemistry|date=January 1995|volume=34|issue=1|pages=116–119|doi=10.1021/ic00105a021}} 3. ^1 2 {{cite journal|last1=Haaland|first1=Arne|last2=Hammel|first2=Andreas|last3=Rypdal|first3=Kristin|last4=Swang|first4=Ole|last5=Brunvoll|first5=Jon|last6=Gropen|first6=Odd|last7=Greune|first7=Michael|last8=Weidlein|first8=Johann|last9=Nasiri|first9=Ahmad|last10=Okada|first10=Yoshito|title=Molecular Structure of Pentamethylantimony by Gas Electron Diffraction; Structure and Bonding in Sb(CH3)5 and Bi(CH3)5 Studied by Ab Initio MO Calculations.|journal=Acta Chemica Scandinavica|date=1993|volume=47|pages=368–373|doi=10.3891/acta.chem.scand.47-0368}} 4. ^1 2 {{cite journal|last1=Downs|first1=A. J.|last2=Schmutzler|first2=R.|last3=Steer|first3=I. A.|title=The vibrational spectrum and structure of pentamethylantimony|journal=Chemical Communications (London)|date=1966|issue=8|pages=221|doi=10.1039/C19660000221|url=https://www.researchgate.net/profile/Anthony_Downs/publication/250807224_The_vibrational_spectrum_and_structure_of_pentamethylantimony/links/00b49520e83d47a16d000000.pdf}} 5. ^{{cite journal|last1=Feher|first1=Frank J.|last2=Budzichowski|first2=Theodore A.|last3=Rahimian|first3=Kamyar|last4=Ziller|first4=Joseph W.|title=Reactions of incompletely-condensed silsesquioxanes with pentamethylantimony: a new synthesis of metallasilsesquioxanes with important implications for the chemistry of silica surfaces|journal=Journal of the American Chemical Society|date=May 1992|volume=114|issue=10|pages=3859–3866|doi=10.1021/ja00036a038}} 6. ^{{cite journal|last1=Graves|first1=Guy E.|last2=Van Wazer|first2=John R.|title=Methyl group replacement on pentamethylantimony with organophosphorus substituents|journal=Journal of Organometallic Chemistry|date=May 1978|volume=150|issue=2|pages=233–237|doi=10.1016/S0022-328X(00)84725-7}} 7. ^{{cite journal|last1=Bos|first1=Klaas D.|last2=Bulten|first2=Eric J.|last3=Meinema|first3=Harry A.|last4=Noltes|first4=Jan G.|title=Synthesis of bis(tetramethylstibonium)tetracyclopentadienylstannate a novel type of organotin(II) compound|journal=Journal of Organometallic Chemistry|date=20 March 1979|volume=168|issue=2|pages=159–162|doi=10.1016/s0022-328x(00)83270-2}} 8. ^1 2 {{cite book|author=Hubert Schmidbaur|title=Advances in Organometallic Chemistry|date=1976|publisher=Academic Press|isbn=9780080580159|url=https://books.google.com.au/books?id=rhM8auhrK5MC&pg=PA235|language=en}} 9. ^{{cite journal|last1=Wang|first1=Y.|last2=Morrow|first2=B. A.|title=Infrared Study of the Chemisorption of Pentamethylantimony on Silica|journal=Langmuir|date=January 1996|volume=12|issue=17|pages=4153–4157|doi=10.1021/la951514s}} 2 : Organoantimony compounds|Hypervalent molecules |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。