- Europium(II) and Ytterbium(II) Cyclic Organohydroborates: An Europium(II) Complex with an Agostic Interaction
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Lanthanide bis((cyclooctane-1,5-diyl)dihydroborate) complexes (THF) 4Ln{(μ-H)2BC8H14}2 (Ln = Eu, 1; Yb, 2) were synthesized by a metathesis reaction between (THF) xLnCl2 and K[H2BC8H14] in THF in a 1:2 molar ratio. Attempts to prepare the monosubstituted lanthanide cyclic organohydroborates (THF)xLnCl{(μ-H)2BC 8H14} were unsuccessful. On the basis of the molecular structure and IR spectrum of 1, there is an agostic interaction between Eu(II) and one of the α-C-H hydrogens from the {(μ-H)2BC 8H14} unit. No such interaction was observed for 2. The coordinated THF in 1 and 2 can be removed under dynamic vacuum, but the solvent ligands remain bound to Yb when 2 is directly dissolved in Et2O or toluene. In strong Lewis basic solvents, such as pyridine or CH3CN, attack of the Yb-H-B bridge bonds results. Decomposition of 2 to the 9-BBN dimer in CD2Cl2 was observed by 11B and 1H NMR spectroscopies. Compound 2 was reacted with 2 equiv of the hydride ion abstracting reagent B(C6F5)3 to afford the solvent-separated ion pair [Yb(THF)6][HB(C 6F5)3]2 (3). Complexes 1, 2, and 3 were characterized by single-crystal X-ray diffraction analysis. Crystal data: 1 is orthorhombic, Pna21, a = 21.975(1) A, b = 9.310(1) A, c = 16.816(1) A, Z = 4; 2 is triclinic, P1, a = 9.862(1) A, b = 10.227(1) A, c = 10.476(1) A, α = 69.87(1)°, β = 76.63(1)°, γ = 66.12(1)°, γ = 1; 3.Et2O is triclinic, P1, a = 13.708(1) A, b =14.946(1) A, c = 17.177(1) A, α = 81.01(1)°, β = 88.32(1)°, γ = 88.54(1)°, Z = 2.
- Chen, Xuenian,Lim, Soyoung,Plecnik, Christine E.,Liu, Shengming,Du, Bin,Meyers, Edward A.,Shore, Sheldon G.
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- Stable Push-Pull Disilene: Substantial Donor-Acceptor Interactions through the Si-Si Double Bond
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The push-pull effect has been widely used to effectively tune -electron systems. Herein, we report the synthesis and properties of 1-amino-2-boryldisilene 1 as the first push-pull disilene. Its spectroscopic and structural features show substantial intera
- Kosai, Tomoyuki,Iwamoto, Takeaki
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- Synthesis, structural characterization, and reactions of cyclic organohydroborate half-zirconocene compounds
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Cyclic organohydroborate complexes of zirconium monocyclopentadienyl CpZr{(μ-H)2BC5H10}3, 1, and CpZr{(μ-H)2BC8H14}3, 2, were prepared from the reaction of CpZrCl3 with 3 mol of K[H2BC5H10] and K[H2BC8H10] respectively, in diethyl ether. Compounds 1 and 2 react with the hydride ion abstracting agent B(C6F5)3 to form the same salt [CpZr(OEt)(OEt2)(μ-OEt)]2 [HB(C6F5)3]2, 5. The complexes CpZr(Cl){(μ-H)2BC8H14}2, 3, and Cp*Zr(Cl){(μ-H)2BC8H14}2 [where Cp* = C5(CH3)5], 4, were prepared from the reaction of CpZrCl3 and Cp*ZrCl3 with K[H2BC8H10] in 1:2 molar ratios, respectively. An α-hydrogen of a BC8H14 unit forms an agostic interaction with Zr in compound 3 but not in 4. All of the compounds were characterized by single-crystal X-ray diffraction analysis.
- Ding, Errun,Liu, Fu-Chen,Liu, Shengming,Meyers, Edward A.,Shore, Sheldon G.
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- Synthesis and x-ray and neutron structures of Zr{(μ-H) 2BC8H14}4
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The complex Zr(9-BBN)4 [9-BBN = (μ-H)2BC 8H14] has been synthesized via the reaction of K(9-BBN) with ZrCl4 in diethyl ether. The structure of the title compound has been determined by X-ray and neutron single-crystal diffraction techniques. Each 9-BBN ligand is coordinated to the Zr atom via two B-H-Zr bridges, and these metal-ligand bonding interactions are further augmented by three prominent C-H...Zr agostic interactions. Average molecular parameters derived from the neutron analysis: Zr-H = 2.051(8) A, B-H = 1.286(7) A, Zr...B = 2.409(6) A, Zr-H-B = 87.7(4)°, H-Zr-H = 58.9(3)°. The Zr...H distances corresponding to the three C-H...Zr agostic interactions are 2.424(7), 2.663(8), and 2.551(7) A. The fourth potential C-H...Zr interaction has a Zr...H distance [3.146(7) A] that is too long to be considered in the agostic range. Single-crystal X-ray diffraction data were collected on an Enraf-Nonius Kappa CCD diffraction system, and neutron diffraction data were collected on the quasi-Laue diffractometer VIVALDI at the Institut Laue-Langevin; the final agreement factor for the neutron analysis is 6.52% for 2557 reflections with I > 2σ(I).
- Ding, Errun,Du, Bin,Meyers, Edward A.,Shore, Sheldon G.,Yousufuddin, Muhammed,Bau, Robert,McIntyre, Garry J.
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- A boron-nitrogen transborylation enabled, borane-catalysed reductive cyanation of enones
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Cyanation offers a simple method for the introduction of a nitrile group into organic molecules and an orthogonal route for the installation of a wide array of functional groups using simple transformations. Cyanation methods are dominated by transition metal catalysis and the use of hydrogen cyanide gas. Here, the electrophilic cyanation of enones was achieved using a main-group catalyst and a non-toxic, electrophilic cyanide source. This protocol was applied across a broad substrate scope including those containing reducible functional groups. Mechanistic studies indicated an amino-borane intermediate which underwent B-N transborylation (B-N/B-H exchange) to achieve catalytic turnover.
- Benn, Kieran,Nicholson, Kieran,Langer, Thomas,Thomas, Stephen P.
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p. 9406 - 9409
(2021/09/22)
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- 9 - boron bicyclo [3.3.1] nonane dimer synthesis method
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The invention relates to a synthesis method of a 9-borabicyclo[3.3.1]nonane dimer. The synthesis method is used for synthesizing the 9-borabicyclo[3.3.1]nonane dimer by performing a hydroboration reaction on a hydroboron, an oxidizing agent and 1,5-cyclooctadiene as the raw materials in a solvent selected from ethers, aromatic hydrocarbons, aliphatic hydrocarbons and the like under the protection of an inert gas. The synthesis method is simple and convenient to operate, mild in conditions, low in cost, high in product yield and product purity, and suitable for certain scale industrial production.
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Paragraph 0040
(2017/02/09)
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- Lewis base activation of Lewis acids: Group 13. in situ generation and reaction of borenium ions
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A variety of Lewis bases were combined with 9-BBN-NTf2 to establish the requirements for the generation of borenium cations. Five different types of behaviors were found, but the most interesting was the combination of Et3N, DABCO, 2,6-lutidine, or Ph3P=S, which formed borenium ions exclusively even in sub- or superstoichiometric quantities. The 9-BBN borenium ion complex of 2,6-lutidine rapidly catalyzes the hydrosilylation of a variety of ketones in the presence of Et3SiH. Preliminary mechanistic experiments suggest that the reduction involves borenium ion activation of Et3SiH and not the ketone.
- Denmark, Scott E.,Ueki, Yusuke
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supporting information
p. 6631 - 6634
(2014/01/06)
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- Tris(2,6-diisopropylphenolato)titanium(IV) dihydridodiorganylborates: Synthesis and structures
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The reactions of tris(2,6-diisopropylphenolato)titanium(IV) chloride with alkali-metal dihydridodiorganylborates M(H2BR2) (M = Li, K; R = Me, C6H11, CMe3; BR2 = BC5H10, BC8H14) led to the corresponding titanium dihydridodiorganylborates. However, in almost all cases byproducts such as (2,6-diisopropylphenolato)diorganylboranes, triorganylboranes, diorganylboranes, diborane and tetrakis(2,6- diisopropylphenolato)titanium(IV) were also generated. (2,6-iPr 2C6H3O)3Ti(H2BR 2) compounds also resulted from the interaction of methyltris(2,6-diisopropylphenolato)titanium, for example, with catecholborane. In addition to the formation of tris(2,6-diisopropylphenolato) catecholboratotitanium(IV), B-methylcatecholborane was also formed The reaction of potassium dihydro-9-cyclooctylborate with 2,6-bis(2,2-di-tert-butyl-2- hydroxyethyl)pyridinetitanium dichloride (LTiCl2) led to the complex LTi(H2BC8H14)2. This compound showed no agostic C-H···Ti interaction in contrast to (2,6-iPr2C6H3O)3TiH 2BC8H14 and the corresponding titanium dihydridobis(cyclohexyl)borate.
- Knizek, Joerg,Noeth, Heinrich
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p. 1888 - 1900
(2011/06/26)
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- Reductive cleavage of acetals and ketals with 9-borabicyclo[3.3.1]nonane
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The reductive cleavage of benzaldehyde acetals and acetophenone ketals with the air-stable crystalline 9-borabicyclo[3.3.1]-nonane dimer provides monobenzylated ether derivatives of diols and 1,2-oxygen-transposed β-phenethyl alcohols, respectively. The boron moiety is effectively recovered through simple procedures which involve convenient air-stable reagents and boron byproducts. The process is particularly selective for 1,3-diols giving the more substituted monobenzyl ether derivatives exclusively. With acetophenone ketals both reduction and elimination occur, permitting 9-BBN-H to hydroborate the resulting styrene to produce 1,2-oxygen-transposed β-phenethyl alcohols cleanly. Potential applications of this new process were illustrated with the synthesis of the hallucinogen, mescaline, and the analgesic, ibufenac.
- Soderquist, John A.,Kock, Iveliz,Estrella, Maria E.
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supporting information
p. 1076 - 1079
(2012/12/23)
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- Preparation and crystal structures of a series of titanium(III) 9-BBN hydroborate complexes containing Ti...H agostic interactions
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9-BBN hydroborate complexes Ti{(μ-H)2BC8H 14}3(THF)2 (1), Ti{(μ-H)2BC 8H14}3(OEt2) (2), and [K(OEt 2)4]-[Ti{(μ-H)2BC8H 14}4] (4) were formed from the reaction of TiCl 4 with K[H2BC8H14] in diethyl ether or THF. Ti{(μ-H)2BC8H14} 3(PhNH2) (3) was isolated from the reaction of 2 with aniline in diethyl ether. In the formation of these complexes, Ti(IV) is reduced to Ti(III). The coordinated diethyl ether in 2 can be displaced by the stronger bases THF and aniline, to form 1 and 3, respectively. All of the compounds were characterized by single-crystal X-ray diffraction analysis. In complex 1, which contains two coordinated THF ligands, the titanium possesses a 17 electron configuration and there is no evidence for agostic interaction. Complexes 2 and 3 contain only one coordinated ether or aniline ligand, and the titanium possesses a 15 electron configuration. In these compounds, a C-H hydrogen on an α carbon on the BC8H14 unit of a 9-BBN hydroborate ligand forms an agostic interaction with the titanium. Criteria for assessing the existence of agostic interactions are discussed. As the potassium salt, the anion of complex 4 is more stable than the complexes 1-3. Organometallic anions of the type [ML4]- for titanium(III) are rare.
- Ding, Errun,Du, Bin,Liu, Fu-Chen,Liu, Shengming,Meyers, Edward A.,Shore, Sheldon G.
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p. 4871 - 4878
(2008/10/09)
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- Effect of solvent in the reaction of Cp2ZrH{(μ-H)2BR2} (R2 = C4H14, C 8H14) with B(C6F5)3: Formation of [HB(C6F5)3]- salts of the unsupported hydrogen-bridged cations [(μ-H){Cp2Zr(μ-H)(2)Br(2)}(2)](+) (R(2) = C (4)H(8), C(8)H(14)) and [Cp(2)Zr(OEt(2))X](+) (X = OEt, {(μ-H)(2)BC(8)H(14)})
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Hydride abstraction reactions of the zirconocene cyclic organohydroborate complexes Cp2ZrH{(μH)2BR2} (R2 = C4H8,1; C3H14, 2) with B(C 8F5)3 were observed as a function of solvent. The reaction in poorly coordinating solvents, benzene and toluene, forms [HB(C6F5)3]- salts of Zr-H-Zr hydrogen-bridged cations [(μ-H){Cp2Zr(μ-H)2BR 2}2]+ (R2 = C4H 8, 3; C8H14, 4), in which there is no direct metal-metal bonding between the bridged metals. The unsupported hydrogen-bridged bond in complex 4 was cleaved when it was dissolved in the coordinating solvent THF to produce the neutral complex 2 and the ionic complex [Cp 2Zr(THF){(μ-H)2BC6H14}][HB(C 6F5)3]. In the coordinating solvent, diethyl ether, the salts of [Cp2Zr(OEt2)X]+[HB(C 6F5)3]- (X = OEt, 5; {(-H) 2BC8H14}, 6) consisting of zirconocene cations with coordinated solvent ligands were isolated. The formation of 5 involves hydride insertion from zirconium into the carbon oxygen bond of one the coordinated ethers, resulting in the liberation of ethane and the formation of an ethoxyl group coordinated to zirconium. The diethyl ether molecules in the cations 5 and 6 are weakly coordinated to Zr and are displaced in THF solution. Single-crystal X-ray structures of 3, 4, and 5 were determined.
- Chen, Xuenian,Liu, Fu-Chen,Plecnik, Christine E.,Liu, Shengming,Du, Bin,Meyers, Edward A.,Shore, Sheldon G.
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p. 2100 - 2106
(2008/10/09)
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- Cyclic organohydroborate complexes of metallocenes. VII. Synthesis, structure, and fluxional behavior of Cp2ZrX{(μ-H)2BC8H14} (X = H, D, Cl)
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The reaction of K[H2BC8H14] with Cp2ZrCl2 in a 1:1 molar ratio afforded Cp2ZrCl{(μ-H)2BC8H14}, 1, which when reacted with KH yielded Cp2ZrH{(μ-H)2BC8H14}, 2. These complexes were structurally characterized by single-crystal X-ray analysis. Partially deuterated 1 and 2, complexes Cp2ZrCl{(μ-D)(μ-H)BC8H14}, 3, and Cp2ZrD{(μ-H)2BC8H14}, 4, were prepared. 2H NMR spectra revealed that in complex 3, which contains a terminal chloride on zirconium, no exchange of bridge and Cp hydrogens occurred. However, in complex 4, which includes a terminal hydrogen on zirconium, there was facile mixing of terminal, bridge, and Cp-hydrogens. Furthermore, exchange of terminal zirconium-hydrogen with bridge hydrogen was more rapid than exchange with the Cp-hydrogen. Additionally, this fluxional behavior occurred even at room temperature and in the solid state. Variable-temperature 1H NMR studies are consistent with these results of dynamic hydrogen exchange in complexes 1 and 2. The complexes Cp2Nb{(μ-H)2BC8H14}, 7, and Cp2Nb{μ-D)(μ-H)-BC8H14}, 8, have no terminal hydrogen on niobium, and there is no exchange between bridging hydrogens and Cp-hydrogens. The possible participation of the 9-BBN unit ({(μ-H)2BC8H14}) hydrogens in dynamic exchange was examined for 2, the 9-BBN dimer ((C8H14B)(μ-H)2(BC8H14 )), and the 9-BBN anion ([H2BC8H14]) through the partially deuterated complexes Li[(D)(H)BC8H14], 5, and (C8H14B)(μ-D)(μ-H)(BC8H14), 6.
- Chen, Xuenian,Liu, Shengming,Plecnik, Christine E.,Liu, Fu-Chen,Fraenkel, Gideon,Shore, Sheldon G.
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p. 275 - 283
(2008/10/08)
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