- Structural chemistry of arachno-nonaboranes
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Single-crystal conventional-tube and synchrotron X-ray diffraction studies of the anions in [NMe4]-[arachno-B9H12-4,8-Br2] 1 and K[arachno-B9H14] 2, and also of the series of adducts [arachno-B9H13-4-L], where L is P(CCH)3 (3), NHEt2 (4), NC5H5 (5), or NH2CH2Ph (6), are reported. Structural studies of 1 - 6, determined at low temperatures, located all atoms, including bridging and endo-terminal hydrogen atoms. The basic boron-hydride clusters of these, and of all the other known species with the arachno nine-vertex i-nonanborane geometry reported in the literature, are isostructural and feature three bridging and two endo-terminal hydrogen atoms on the open face. This arrangement is different from that previously reported for Cs[arachno-B9H14] 7 and for [arachno-B9H13-4-(NCMe)] 9. However, a new X-ray diffraction data set and refinement experimentally confirm the {3 × μ-H, 2× endo} arrangement for 9 also. The experimental results for 1 - 6 support recently reported calculations for [B9H14]-, which predict both the structures and the 11B NMR chemical shifts. These conclusions are also supported by calculations for 3, 4, and 9 and also for the [arachno-B9H13-4-(NCS)]- anion in [NMe4][B9H13(NCS)] 8.
- Bould, Jonathan,Greatrex, Robert,Kennedy, John D.,Ormsby, Daniel L.,Londesborough, Michael G. S.,Callaghan, Karen L. F.,Thornton-Pett, Mark,Spalding, Trevor R.,Teat, Simon J.,Clegg, William,Fang, Hong,Rath, Nigam P.,Barton, Lawrence
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- Method for preparing bunch of boron
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New methods are provided for synthesis of ClusterBoron (B18H22). Preferred methods of the invention include generation of the conjugate acid of B20H182? and degradation of the acid in solution to produce B18H22 in high yields and high purity. The invention further provides isotopically enriched boranes, particularly isotopically enriched 10B18H22 and 11B18H22.
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Paragraph 0035; 0043-0044
(2018/02/04)
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- An experimental solution to the missing hydrogens question surrounding the macropolyhedral 19-vertex boron hydride monoanion [B 19H22]-, a simplification of its synthesis, and its use as an intermediate in the first example of syn -B18H 22 to anti -B18H22 isomer conversion
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The macropolyhedral [B19H22]- monoanion 1 and the dianion [B19H21]2- 2 are synthesized in consistent 86-92% yields by the reaction of [PSH]+[syn-B 18H21]- with BH3(SMe2) in 1,2-Cl2C2H4 at 72 °C. [PS is an abbreviation for Proton Sponge, 1,8-bis-(dimethylamino)naphthalene. PSH is its protonated derivative.] The molecular structures of 1 and 2 were elucidated as their [PS{BH2}]+ and [PS{BH2}]2 + salts 1a and 2a by single-crystal X-ray diffraction studies, in which all atoms were located, and supported by mass spectrometric analyses together with calculations of the cluster molecular geometries (ab ignitio and/or DFT) and of 11B chemical shifts based on GIAO-DFT shielding tensors. Acidification of dianion 2 with CF3COOH in acetonitrile, H2SO4 in dichloromethane, or aqueous HCl results in the clean formation of the monoanion [B19H22]- 1. Conversely, shaking a concentrated acetonitrile solution of 1 in 0.5 M aqueous NaOH cleanly yields the [B19H21]2- dianion 2. Reaction of a dichloromethane solution of 1 with a 36% aqueous solution of HCHO in the presence of H2SO4 quantitatively converts 1 at room temperature to a 1:1 mixture of the syn- and anti-isomers of B 18H22. This cluster dismantling process is the first example of a syn- to anti-B18H22 isomer conversion.
- Londesborough, Michael G. S.,Bould, Jonathan,Base, Tomas,Hnyk, Drahomir,Bakardjiev, Mario,Holub, Josef,CisaRova, Ivana,Kennedy, John D.
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p. 4092 - 4098
(2010/07/04)
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- Improved synthetic route to n-B18H22
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Simple iodine oxidation of the B9H12- anion in toluene at room temperature reliably gives excellent yields (~80%) of n-B18H22 (anti-B18H22) and thus provides a convenient, large-scale, safe route to this important polyborane cluster.
- Li, Yuqi,Sneddon, Larry G.
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p. 470 - 471
(2008/10/09)
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- Metal-Promoted Fusion and Linkage of B5H81-, 1-XB5H71-, (X = D, CH3), B10H131-, and (ε5-C5H5)CoB4H71-. Facile Routes to B10H14 and (η5-C5H5)2Co2B8H10 Isomers.
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This study examined the conversions, via oxidative fusion or coupling, of B5H81- to B10H14 and 2,2'-(B5H8)2 in the presence of FeCl2/FeCl3, of B5H81- to B10H14 alone in the presence of RuCl3, and of 1-XB5H71- (X = D and CH3) to 2,4-B10H12D2 and 2,2-(1-CH3B5H7)2 with RuCl3 or FeCl2/FeCl3.The B10H131- ion was shown to form n- and i-B18H22 on treatment with RuCl3 in THF and subsequent exposure to air.The RuCl3-promoted fusions of the square-pyramidal cobaltaboranes 2-(ε5-C5H5)CoB4H71- and 1-(ε5-C5H5)CoB4H71- (both analogues of B5H81- to give nido-(η-C5H5)2Co2B8H12 isomers were also studied.The 2-isomer yields primarily 5,8-, 1,5-, and 1,7-(η-C5H5)2Co2B8H12, while the 1-isomer affords only 2,4-(η5-C5H5)2Co2B8H12.All these observations support a fusion mechanism in which two square-pyramidal substrate molecules, facilitated by coordination to a common metal ion, are initially joined at their basal edges and then complete the fusion process to give a nido 10-vertex cage in which the original apex (1-vertex) atoms become the 2,4-vertexes in the product.The new compounds were characterized via infrared, 11B and 1H NMR, mass spectra, and in some cases by two-dimensional (2D) 11B homonuclear NMR.
- Brewer, Cynthia T.,Grimes, Russell N.
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p. 3552 - 3558
(2007/10/02)
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