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71.
The reaction of 1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4-diisopropyltetrasila-2-yne (1) with tert-butylisocyanide or tert-octylisocyanide produced the corresponding disilyne-isocyanide adducts [RSiSiR(CNR')(2)] (R = Si(i)Pr[CH(SiMe(3))(2)](2), R' = (t)Bu (2a) or CMe(2)CH(2)(t)Bu (2b)), which are stable below -30 °C and were characterized by spectroscopic data and, in the case of 2a, X-ray crystallography. Upon warming to room temperature, 2 underwent thermal decomposition to produce 1,2-dicyanodisilene R(NC)Si═Si(CN)R (3) and 1,2-dicyanodisilane R(NC)HSiSiH(CN)R (4) via C-N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative 3 was characterized by X-ray crystallography. 相似文献
72.
Ichinohe M Toyoshima M Kinjo R Sekiguchi A 《Journal of the American Chemical Society》2003,125(44):13328-13329
The first silicon cage anion, tris{bis[bis(trimethylsilyl)methyl](methyl)silyl}tetrasilatetrahedranide (6-), has been synthesized by the reaction of tetrakis{bis[bis(trimethylsilylmethyl](methyl)silyl}tetrasilatetrahedrane with potassium graphite in diethyl ether by reductive cleavage of exocyclic Si-Si bond. The structural characterization of K+(18-crown-6).6- has been achieved by X-ray crystallography, showing that 6- is a separated ion pair and the tetrasilatetrahedranide moiety has a significantly distorted tetrahedrane skeleton containing one inverted tetrahedral (umbrella type) silicon atom. The four silicon atoms in the Si4 skeleton are equivalent on the NMR time scale due to the migration of the Dis2MeSi substituent. 相似文献
73.
M. Fukushima N. Horikawa R. Kajikawa H. Kobayakawa K. Mori T. Nakanishi C.O. Pak S. Suzuki T. Matsuda N. Tokuda M. Daigo T. Ohshima 《Nuclear Physics B》1977,130(3):486-504
The polarized target asymmetry for the process γp → π+n has been measured for incident photon energies below 1.02 GeV over a range of c.m. angles from 40° to 160°. π+ mesons from a polarized butanol target were detected by a magnetic spectrometer. The results are compared with predictions given by existing analyses. A tentative interpretation of the data is performed, and a larger contribution of S-wave resonances is suggested. The photocouplings of dominant resonances were hardly changed by the inclusion of new data and they seem to be almost uniquely determined. 相似文献
74.
75.
Sato H Shimada K Arita M Hiraoka K Kojima K Takeda Y Yoshikawa K Sawada M Nakatake M Namatame H Taniguchi M Takata Y Ikenaga E Shin S Kobayashi K Tamasaku K Nishino Y Miwa D Yabashi M Ishikawa T 《Physical review letters》2004,93(24):246404
Yb 3d and valence-band photoemission spectra of the first-order valence-transition compound YbInCu4 have been measured with hard x ray at an excitation energy of 5.95 keV. Abrupt changes are clearly observed in both spectra around the transition temperature T(V)=42 K, in comparison with ultraviolet and soft x-ray photoemission (VUV-PES and SX-PES) spectra. From the Yb 3d spectra, the Yb valence has been estimated to be approximately 2.90 from 220 down to 50 K and approximately 2.74 at 30-10 K. We propose that Yb 3d hard x-ray photoemission spectroscopy is a very powerful method to estimate the valence of Yb with high accuracy. On the other hand, the Yb2+ 4f-derived peaks in the valence-band spectra exhibit a remarkable enhancement below T(V). The shape of the valence-band spectra is different from those of the VUV-PES and SX-PES spectra above T(V), reflecting the In 5s and 5p contributions. 相似文献
76.
Takaki H Haba J Abe K Amako K Arai Y Arima T Asano Y Chiba M Chiba Y Daigo M Fukawa M Fukushima Y Hemmi Y Higuchi M Hinode F Hirose T Homma Y Hoshi Y Hosoda N Ishihara N Kanatani E Kanda N Kanematsu N Kanzaki J Kikuchi R Kondo T Korhonen TT Krüger AE Kurashige H MacNaughton J Matsui T Miyake K Miura M Mori S Nagashima Y Nakamura T Nakano I Odaka S Ogawa K Ohama T Ohsugi T Ohyama H Okamoto A Ono A Oyama T Sakamoto H Sakuda M Sato M Sato N Shioden M Shirai J Shirakata M Sumiyoshi T Suzuki A 《Physical review letters》1993,71(1):38-41
77.
Sekiguchi A Fukawa T Nakamoto M Lee VY Ichinohe M 《Journal of the American Chemical Society》2002,124(33):9865-9869
The one-electron oxidation reaction of tris[di-tert-butyl(methyl)silyl]silyl and -germyl anions with dichlorogermylene-dioxane complex results in the formation of stable tris[di-tert-butyl(methyl)silyl]silyl and -germyl radicals 1 and 2, representing the first isolable radical species of heavier Group 14 elements lacking stabilization by conjugation with pi-bonds. The crystal structures of both silyl and germyl radicals 1 and 2 showed a completely planar geometry around the radical centers. The ESR spectra of 1 and 2 showed strong signals with characteristic satellites due to the coupling with the 29Si and 73Ge nuclei. The small values of the hyperfine coupling constants a(29Si) and a(73Ge) clearly indicate the pi-character of both radicals, corresponding to a planar geometry and sp2 hybridization of the radical centers. Both 1 and 2 easily undergo halogenation reactions with carbon tetrachloride, 1,2-dibromoethane, and benzyl bromide to form the corresponding halosilanes and halogermanes. 相似文献
78.
Sekiguchi A Ishida Y Kabe Y Ichinohe M 《Journal of the American Chemical Society》2002,124(30):8776-8777
The heavier group 14 element cation cluster compound, [(tBu3Si)6Ge10I]+.TTFPB- (3+. TTFPB-; TTFPB- = tetrakis(2,3,5,6-tetrafluorophenyl)borate), was unexpectedly obtained by thermolysis of in situ prepared iodocyclotrigermene, (tBu3Si)3Ge3I, in toluene in the presence of KI and K+.TTFPB-. The molecular structure of 3+.TTFPB- has been unambiguously determined by X-ray crystallography, showing that 3+ is a free germyl cation. The three "naked" cationic germanium atoms in the framework constitute a three-center two-electron (3c-2e) bond with a trishomocyclotrigermenylium character, which is well-supported by a theoretical calculation on the model compound Ge10H7+. 相似文献
79.
Nakata N Izumi R Lee VY Ichinohe M Sekiguchi A 《Journal of the American Chemical Society》2004,126(16):5058-5059
The first compounds containing Si=Ga or Si=In double bonds, 1,3-disila-2-gallata- (2-) and -indataallenic anions (3-), were obtained in the form of lithium salts as dark red crystals by the reaction of bis(di-tert-butylmethylsilyl)dilithiosilane 1 with GaCl3 or InCl3. X-ray crystallographic analysis of 2-.[Li(thf)4]+ and 3-.[Li(thf)4]+ showed that the >SiMSi< frameworks (M = Ga, In) are not linear and the two Si=M bond lengths are about 9% shorter than typical Si-M single bonds. In the 29Si NMR spectra, the signals of the terminal Si atoms in 2- and 3- are greatly shifted upfield (2-: -79.9; 3-: -77.6 ppm). The NPA charge distribution for the model compound, [(Me3Si)2SiGaSi(SiMe3)2]- (4-) showed a large part of the negative charge localizing on the two terminal silicon atoms (-0.736 and -0.729). In addition, 2-.[Li(thf)4]+ reacted with MeI to give the corresponding iodogallane 5 nearly quantitatively. This result confirms that the allenic [>SiMSi<]- fragments are highly polarized. 相似文献
80.
Lee VY Takanashi K Ichinohe M Sekiguchi A 《Journal of the American Chemical Society》2003,125(20):6012-6013
The unexpected reaction of tetrakis[di-tert-butyl(methyl)silyl]disilagermirenes (1a and 1b) with GeCl2.dioxane results in the quantitative formation of trans-1,2-dichloro-1,2,3,4-tetrakis[di-tert-butyl(methyl)silyl]-3Delta-1,2,3,4-disiladigermetene, 2, representing the first cyclotetrametallene containing two different heavier group 14 elements and the first digermene incorporated in a four-membered ring. trans-1,2-Dichloro-1,2,3,4-tetrakis[di-tert-butyl(methyl)silyl]-3Delta-1,2,3,4-disilagermastannetene (8), with a Ge=Sn double bond, was also prepared by the reaction of 1 with SnCl2.dioxane. The crystal structure of 2 was established by X-ray crystallography, which showed a folded four-membered ring skeleton with a long Ge=Ge double bond (2.2911(4) A). The structural peculiarities of 2, as well as the possible mechanism of its formation, are also discussed. 相似文献