1,2-Dimethyldiborane

1,2-Dimethyldiborane changed changed cis-1,2-dimethyldiborane.svg skin-invert-image 150px cis-1,2-Dimethyldiborane trans-1,2-dimethyldiborane.svg skin-invert-image 150px trans-1,2-Dimethyldiborane 1,2-Dimethyldiborane(6) Symmetrical dimethyldiborane 17156-88-6 incorrect CAS C[BH]1[H][BH](C)[H]1 1S/C2H10B2/c1-3-5-4(2)6-3/h3-4H,1-2H3 CMZSWMSJMMTTMF-UHFFFAOYSA-N (CH3BH2)2 55.72 g mol−1 Colorless gas -124.9 4 1,2-Dimethyldiborane is an organoboron compound with the formula [(CH3)BH2]2. Structurally, it is related to diborane, but with methyl groups replacing terminal hydrides on each boron. It is the dimer of methylborane, CH3BH2, the simplest alkylborane.Srebnik Morris Cole Thomas E. Brown Herbert C. Methylborane - a remarkable unhindered monoalkylborane which achieves the controlled sequential hydroboration of representative alkenes Tetrahedron Letters January 1987 28 33 3771–3774 10.1016/s0040-4039(00)96380-9 1,2-Dimethyldiborane can exist in a cis- and a trans arrangement.Low M. J. D. Characteristic Infrared Frequencies of Methyldiboranes The Journal of Chemical Physics 1968 48 5 2386–2387 10.1063/1.1669454 1968JChPh..48.2386L 1,2-Dimethyldiborane is an easily condensed, colorless gas that ignites spontaneously in air. An isomer of 1,2-dimethyldiborane is 1,1-dimethyldiborane, known as unsymmetrical dimethyldiborane, which has two methyl groups on one boron atom. Other methylated versions of diborane including methyldiborane, trimethyldiborane, tetramethyldiborane. Trimethylborane exists as a monomer. Preparation Methylboranes were first prepared by H. I. Schlesinger and A. O. Walker in the 1930s.Long L. H. Wallbridge M. G. H. 646. The Chemistry of Boron. Part VI. New Preparative Methods and Decomposition Studies Relating to Methyldiboranes Journal of the Chemical Society (Resumed) 1965 3513–3520 10.1039/JR9650003513 http://pubs.rsc.org/en/content/articlepdf/1965/jr/jr9650003513 subscription Schlesinger H. I. Walker A. O. Hydrides of Boron. IV. The Methyl Derivatives of Diborane Journal of the American Chemical Society April 1935 57 4 621–625 10.1021/ja01307a009 1935JAChS..57..621S In a more modern synthesis, 1,2-dimethyldiborane is produced by treating lithium methylborohydride with hydrogen chloride: 2 LiCH3BH3 + 2 HCl → (CH3BH2)2 + 2 H2 + 2 LiCl Instead of hydrogen chloride, methyl iodide or trimethylsilyl chloride can be used. Lithium methylborohydride can be made by treating methylboronic esters with lithium aluminium hydride.Brown Herbert C. Cole Thomas E. Srebnik Morris Kim Kee Won Hydroboration. 79. Preparation and Properties of Methylborane and Dimethylborane and Their Characteristics as Hydroborating Sgents. Synthesis of Tertiary Alcohols Containing Methyl Groups via Hydroboration The Journal of Organic Chemistry December 1986 51 25 4925–4930 10.1021/jo00375a031 Miscellaneous routes Methylboranes arise the reaction of diborane and trimethylborane. This reaction produces 1-methyldiborane, 1,1-dimethyldiborane, 1,1,2-trimethyldiborane, and 1,1,2,2-tetramethyldiborane. By treating monomethyldiborane with ether, dimethyl ether borane (CH3)2O.BH3 leaving methylborane which rapidly dimerises to 1,2-dimethyldiborane.Bell R. P. Emeléus H. J. The Boron Hydrides and Related Compounds Quarterly Reviews, Chemical Society 1948 2 2 132 10.1039/QR9480200132 The reaction is complex. Tetramethyl lead reacts with diborane to give a range of methyl-substituted diboranes, ending up at trimethylborane, but including 1,1-dimethyldiborane, and trimethyldiborane. Other products are hydrogen gas and lead metal.Holliday A.K. N. Jessop G. The Reaction of Tetramethyllead with Diborane Journal of Organometallic Chemistry November 1967 10 2 291–293 10.1016/s0022-328x(00)93089-4 Other methods to form methyldiboranes include treating hydrogen with trimethylborane between 80 and 200 °C under pressure, or treating a metal borohydride with trimethylborane in the presence of hydrogen chloride, aluminium chloride or boron trichloride. If the borohydride is sodium borohydride, then methane is a side product. If the metal is lithium, then no methane is produced. dimethylchloroborane and methyldichloroborane are also produced as gaseous products. When Cp2Zr(CH3)2 reacts with diborane, a borohydro group inserts into the zirconium-carbon bond, and methyl diboranes are produced.Marsella John A. Caulton Kenneth G. Dealkylation of Zirconium(IV) by Borane: the Intimate Mechanism of an Alkyl Transfer Reaction Journal of the American Chemical Society May 1982 104 9 2361–2365 10.1021/ja00373a005 1982JAChS.104.2361M In ether dimethylcalcium reacts with diborane to produce dimethyldiborane and calcium borohydride:James B. D. Wallbridge M. G. H. Lippard Stephen J. Progress in Inorganic Chemistry, Volume 11 1970 Wiley 0471-54081-1 185 https://books.google.com/books?id=8N6nFvNzfv0C&pg=PA185 Metal Tetrahydroborates Ca(CH3)2 + 2 B2H6 → Ca(BH4)2 + B2H4(CH3)2 1,2-Dimethyldiborane is produced by the room temperature disproportionation of trimethyldiborane.Lehmann Walter J. Wilson Charles O. Shapiro I. Infrared Spectra of Alkyldiboranes. V. Tri- and Tetramethyl- and Ethyldiboranes The Journal of Chemical Physics 1961 34 3 783 10.1063/1.1731675 1961JChPh..34..783L Physical and spectroscopic properties cis-1,2-Dimethyldiborane melts at −132.5 °C; trans-1,2-dimethyldiborane melts at −102 °C.Hedberg Lise Hedberg Kenneth Kohler David A. Ritter David M. Schomaker Verner Electron-diffraction investigations of the molecular structures of cis- and trans-1,2-dimethyldiborane Journal of the American Chemical Society May 1980 102 10 3430–3434 10.1021/ja00530a021 1980JAChS.102.3430H The cis-1,2-dimethyldiborane molecule has point group Cs. A trans-1,2-dimethyldiborane molecule has point group C2. Unsymmetrical dimethyldiborane melts at −150.2 °C.Onak Thomas Stone F. G. A. West Robert Advances in Organometallic Chemistry 1 January 1966 Academic Press New York, London 284 https://books.google.com/books?id=AHEPoIx22iwC&pg=PA284 14 August 2015 9780080580043 Vapour pressure is approximated by Log P = 7.363−(1212/T). The vapour pressure for the symmetrical isomer is given by Log P = 7.523−(1290/T). Gas chromatography can be used to determine the amounts of the methyl boranes in a mixture. The order of elution are: diborane, monomethyldiborane, trimethylborane, 1,1-dimethyldiborane, 1,2-dimethyldiborane, trimethyldiborane, and last tetramethyldiborane.Seely G. R. Oliver J. P. Ritter D. M. Gas-Liquid Chromatographic Analysis of Mixtures Containing Methyldiboranes Analytical Chemistry December 1959 31 12 1993–1995 10.1021/ac60156a032 The nuclear resonance shift for the bridge hydrogen is 9.55 ppm for the unsymmetrical isomer and 9.73 ppm for the symmetrical isomers, compared to 10.49 for diborane.Leach John B. Ungermann Charles B. Onak Thomas P. Proton magnetic resonance studies on methyl and chloro substituted diboranes Journal of Magnetic Resonance January 1972 6 1 74–83 10.1016/0022-2364(72)90088-1 1972JMagR...6...74L Reactions Methylborane shows little tendency to disproportionate (redistribute) at room temperature. It reacts stepwise with alkenes to produce mono and dialkylmethylboranes. More methylated boranes are less stable. 1,2-Dimethyldiborane slowly converts to 1,1-dimethyldiborane.Lehmann Walter J. Wilson Charles O. Shapiro I. Infrared Spectra of Alkyldiboranes. III. 1,2-Dimethyl- and 1,2-Diethyldiboranes The Journal of Chemical Physics 1960 33 2 590 10.1063/1.1731190 1960JChPh..33..590L Methylborane hydrolyzes to methylboronic acid: (MeBH2)2 + 4 H2O → CH3B(OH)2 + 4 H2 Symmetrical dimethyldiborane reacts with trimethylamine to yield a solid adduct trimethylamine-methylborane (CH3)3N·BH2CH3. When dimethyldiborane is combined with ammonia and heated, B-methyl borazoles are produced. These borazoles can have one, two or three methyl groups substituted on the boron atoms.Sheldon J. C. Smith B. C. The borazoles Quarterly Reviews, Chemical Society 1960 14 2 202 10.1039/QR9601400200Schlesinger H. I. Horvitz Leo Burg A. B. Hydrides of Boron. VI. The Action of Ammonia on the Methyl Diboranes Journal of the American Chemical Society March 1936 58 3 409–414 10.1021/ja01294a008 1936JAChS..58..409S Under normal conditions dimethyldiborane does not react with hydrogen.Adams Roy M. Metal-Organic Compounds September 1959 23 92 10.1021/ba-1959-0023.ch010 17 August 2015 https://www.thevespiary.org/rhodium/Rhodium/Vespiary/talk/files/4262-AIC-023-METAL-ORGANIC-COMPOUNDS-13db1.pdf?topic=2297.0 Advances in Chemistry Organoboron Compounds Related species Lithium trihydromethylborate [CH3BH3]−. Isomers of diethyldiborane can be produced by analogous methods.Mikhailov B. M. The Chemistry Of Diborane Russian Chemical Reviews April 1962 31 4 209 1962RuCRv..31..207M 10.1070/RC1962v031n04ABEH001281 250909492 free 1,2- 2,2- and 2,4-dimethyltetraborane,Deever William R. Ritter David M. Methyltetraboranes. I. 2-Methyl and 1,2-, 2,2-, and 2,4-dimethyl derivatives Inorganic Chemistry November 1969 8 11 2461–2467 10.1021/ic50081a043 1,2-dimethylpentaboraneAddison C. C. Inorganic Chemistry of the Main-Group Elements Davidson G. 1973 1 68 10.1039/9781847556370-00053 http://pubs.rsc.org/en/content/chapter/bk9780851867526-00053/978-0-85186-752-6 978-0-85186-752-6 Elements of Group III 2,3-dimethylpentaborane,Onak Thomas Friedman Lawrence B. Hartsuck Jean A. Lipscomb William N. Rearrangement of 1,2- to 2,3-Dimethylpentaborane(9) Journal of the American Chemical Society July 1966 88 14 3439–3440 10.1021/ja00966a051 1966JAChS..88.3439O 4,5-dimethylhexaborane,Shore S. G. Muetterties Earl L Boron Hydride Chemistry 1975 Academic Press 0-12-509650-X 150 https://books.google.com/books?id=hLUy6or0In8C&pg=PA150 Nido and Arachno Boron Hydrides and 5,6- 6,8- 6,9-dimethyldecaborane.Dunstan I. Williams R. L. Blay N. J. 970. Boron hydride derivatives. Part V. Nucleophilic substitution in decaborane Journal of the Chemical Society 1960 IV 5012–5015 10.1039/JR9600005012 http://pubs.rsc.org/en/content/articlepdf/1960/jr/jr9600005012 19 August 2015 subscription References 30em Extra reading Carpenter J. H. Jones W. J. Jotham R. W. Long L. H. Laser-source Raman spectroscopy and the Raman spectra of the methyldiboranes Chemical Communications 1968 15 881 10.1039/C19680000881 Lehmann Walter J. Wilson Charles O. Shapiro I. Infrared Spectra of Alkyldiboranes. I. Monomethyldiboranes The Journal of Chemical Physics 1960 32 4 1088 10.1063/1.1730853 1960JChPh..32.1088L Carpenter J.H. Jones W.J. Jotham R.W. Long L.H. The Raman spectra of the methyldiboranes—I 1, 1-dimethyldiborane and tetramethyldiborane Spectrochimica Acta Part A: Molecular Spectroscopy June 1970 26 6 1199–1214 10.1016/0584-8539(70)80027-7 1970AcSpA..26.1199C Reactions of Methyl Substituted Diboranes and 2,2-Dimethyltetraborane with Amine Bases Francis M. Jungfleisch Ohio State University 1973 https://etd.ohiolink.edu/!etd.send_file?accession=osu1298565601&disposition=inline 30 July 2015 4 March 2016 https://web.archive.org/web/20160304192445/https://etd.ohiolink.edu/!etd.send_file?accession=osu1298565601&disposition=inline dead Borax to Boranes https://www.thevespiary.org/rhodium/Rhodium/Vespiary/talk/files/4264-BORAX-TO-BORANES3db1.pdf?topic=2297.0 134–136 1961 32 Advances in Chemistry Series American Chemical Society Isadore Shapiro C. O. Wilson J. F. Ditter W. J. Lehmann 10.1021/ba-1961-0032.ch014 mass spectroscopy Levison K. A. Perkins P. G. Methylaluminium compounds I. The Electronic Structure of Some Methylaluminium and Methylboron Hydrides Theoretica Chimica Acta 1970 17 1 1–14 10.1007/BF00526759 198179226 charge distribution and atom location calculations Category:Alkylboranes Category:Organic compounds with 2 carbon atoms