排序方式: 共有27条查询结果,搜索用时 272 毫秒
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Vidura D. Thalangamaarachchige Nadeesha J. Silva Daniel K. Unruh Adelia J.A. Aquino Clemens Krempner 《Tetrahedron》2019,75(13):1861-1864
The synthesis, structures and spectroscopic properties of M(MeOCH2CH2OMe2Si)3CBH3 (M-1-BH3) and M(MeOCH2CH2OMe2Si)3SiBH3 (M-2-BH3) (M?=?Li, Na, K) derived from reactions of BH3 with the alkali metal zwitterions [M(MeOCH2CH2OMe2Si)3C] (M-1) and [M(MeOCH2CH2OMe2Si)3Si] (M-2) (M?=?Li, Na, K), resp., are reported. X-ray analysis and DFT calculations reveal discrete zwitterionic structures with the octahedral alkali metal cations rigidly locked and charge separated from the BH3 units via pendant donors groups. Solution experiments with the hydride acceptors B(C6F5)3 and [Ph3C]2[B12C12] indicate that Na-1-BH3 can donate hydrides to form cations of formula [Na(MeOCH2CH2OMe2Si)3CBH2]+. 相似文献
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Oganesyan VS Barclay JE Hardy SM Evans DJ Pickett CJ Jayasooriya UA 《Chemical communications (Cambridge, England)》2004,(2):214-215
The potential of NIS spectroscopy to study the iron-sulfur clusters in metalloproteins is illustrated using model compounds. The origin of the intense low energy transfer bands is discussed. 相似文献
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The hyperfine coupling tensors of muonated radicals in a large single crystal of benzophenone have been determined by measuring
the hyperfine couplings of the radicals as the crystal was rotated about three orthogonal axes.
Signals from four radicals were observed, corresponding to the four molecules per unit cell in the crystal. Due to an ambiguity
in the data we are unable to discriminate between two similar hyperfine coupling tensors. Both lead to an isotropic hyperfine
coupling of \sim32 MHz, contrasting with the solution value of 42 MHz obtained earlier in diethyl ether. The anisotropic components
of the tensor are relatively large, at approximately -15 MHz, -6 MHz and 21 MHz, respectively.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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The potential of μSR in the investigation of molecular dynamics of organometallic compounds is illustrated with applications to the classic metallocene compound, ferrocene. Muonium addition gives two radicals in this case with the slowly relaxing radical showing a repolarisation curve corresponding to a hyperfine field of ca. 200 G suggesting addition to the cyclopentadienyl ring. The temperature dependence of the relaxation of this radical gives an activation energy of ca. 5.4 kJ/mol, in good agreement with QENS and NMR estimates for cyclopentadienyl, ring rotation in this compound. 相似文献
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Cannon RD Jayasooriya UA Tilford C Anson CE Sowrey FE Rosseinsky DR Stride JA Tasset F Ressouche E White RP Ballou R 《Inorganic chemistry》2004,43(22):7061-7067
The mixed-valence double salt K(3)(MnO(4))(2) crystallizes in space group P2(1)/m with Z = 2. The manganese centers Mn1 and Mn2 constitute discrete "permanganate", [Mn(VII)O(4)](-), and "manganate", [Mn(VI)O(4)](2-), ions, respectively. There is a spin-ordering transition to an antiferromagnetic state at ca. T = 5 K. The spin-density distribution in the paramagnetic phase at T = 10 K has been determined by polarized neutron diffraction, confirming that unpaired spin is largely confined to the nominal manganate ion Mn2. Through use of both Fourier refinement and maximum entropy methods, the spin on Mn1 is estimated as 1.75 +/- 1% of one unpaired electron with an upper limit of 2.5%. 相似文献
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Upali A. Jayasooriya Roderick D. Cannon Christopher E. Anson Elisha Karu Ahmed K. Saad John P. Bourke Gordon J. Kearley Ross P. White 《Angewandte Chemie (International ed. in English)》1998,37(3):317-320
Intrinsic and extrinsic forces behind the distortion in metal atom clusters can be readily distinguished provided that the clusters are embedded in a suitable ligand environment and that the tunneling of the protons in the peripheral ligands is then analyzed by inelastic neutron scattering. For the [Cr3O(OOCCH3)6(H2O)3]Cl⋅6 H2O model system studied, the tunneling process is very sensitive to the local environment. Thus a tool is available to allow a better assessment of the cause of structural distortions. 相似文献
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Paul H. Dallin Upali A. Jayasooriya Brian F. Johnson Jack Lewis Stephen F. J. Cox Christopher A. Scott Elisabeth Marseglia 《Hyperfine Interactions》1991,64(1-4):715-719
μSR spectra from a metal carbonyl compound are reproted for the first time. The metal cluster compound Cs2[Os10C(CO)24] shows a temperature dependent signal for implanted muons with the onset of motional narrowing at ca. 200 K. Also observed
is a probable change in the width within the temperature range 40–140 K. A tentative assignment is provided for the muon sites. 相似文献
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