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A convenient synthesis of arachno-6,9-C2B8H14, based on the reduction of nido-5,6-C2B8H12 with sodium tetrahydroborate, is reported. Electrophilic halogenation of the former carborane produced a series of 1-X-6,9-C2B8H13 (X = Cl, Br and I) derivatives whose constitution was established on the basis of their 1H and 11B NMR spectra. 相似文献
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Derivatives of Tr?ger's base (TB) have played important roles in receptor construction due to their rigid V-shape. A new class of these compounds are the oligo-TBs, which can function as cavitands. Herein, we describe both stepwise and one-step (oligomerization) methods suitable for the preparation of linear oligo-TBs. 相似文献
14.
Sergey Sergeyev Sara Stas Adrienne Remacle Christophe M.L. Vande Velde Bohumil Dolenský Martin Havlík Vladimír Král Jan Čejka 《Tetrahedron: Asymmetry》2009,20(16):1918-1923
The separation of enantiomers of several ‘bis- and tris-Tröger’s bases’ by HPLC on commercially available chiral stationary phase Whelk O1 is described for the first time. The observed structure–enantioselectivity relationships are in agreement with the previously established molecular recognition model. For all ‘bis- and tris-Tröger’s bases’ studied, satisfactory to excellent enantioselectivities were observed. 相似文献
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1-Dimethylamine-1-carba-closo-dodecaborane(1), 1-(CH3)2NH-1-CB11H11, can be smoothly demethylated with iodine in weakly alkaline solution to produce 1-methylamine-1-carba-closo-dodecarborane(11), 1-CH3NH2-1-CB11H11. The latter compound undergoes formylation with formaldehyde and iodine to give 1-hydroxymethylene-methylamine-1-carba-closo-dodecaborane(11). Further chemical transformations of both compounds are reported. 相似文献
18.
Janousek Z Dostál R Machácek J Hnyk D Stíbr B 《Dalton transactions (Cambridge, England : 2003)》2006,(39):4664-4671
Reactions between closo-1,2-C(2)B(8)H(10) (1) and amines of general formulation R(1)R(2)NH (where R(1), R(2) = H, H; Me, H; t-Bu, H and Et, Et) resulted in a straightforward cluster expansion and formation of the 11-vertex arachno-azadicarbaboranes of the 1,1-R(1),R(2-)1,6,9-NC(2)B(8)H(11) (2) cluster constitution (where R(1), R(2) = H, H 2a; Me, H 2b; t-Bu, H 2c and Et, Et 2d) in yields 10-75%, depending on the nature of the amine used. The reactions are the first example of a direct closo to arachno transformation in the area of cluster-boron compounds. Compounds 2b and 2c were isolated in two isomeric forms anti- and syn- that differ in the positioning of the t-Bu substituent with respect to the bridging hydrogen site. Deprotonation of compounds 2 generally leads to removal of the bridging proton and formation of the [1,1-R(1),R(2-)1,6,9-NC(2)B(8)H(11)](-) (2-) anions that, in the case of the monoalkylated Me and t-Bu derivatives, adopt only an anti configuration. The structure of anti-2c was determined by X-ray diffraction analysis and the geometries of the parent compound and the corresponding syn and anti isomers were optimised at the RMP2/6-31G* level. The composition of all compounds is consistent with the results of mass spectrometry and multinuclear ((1)H and (11)B) spectroscopy complemented by two-dimensional [(11)B-(11)B]-COSY and (1)H{(11)B(selective)} NMR measurements. Experimental (11)B chemical shifts generally show acceptable agreement with theoretical values calculated by GIAO methods, in particular at GIAO-MP2/II, where possible. 相似文献
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The presented work describes behavior of contact structures of Ni/Ti type on 6H-SiC n-type. The best contact resistivity obtained is 3.3 × 10−4 Ω cm2. The structure showed excellent thermal stability, it was stable after being tested for 10 h at 900 °C. XRD analysis after annealing at 960 °C revealed orthorhombic Ni2Si as the dominate phase. 相似文献
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