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Schultz György Hargittai István Rot Nicolette Bickelhaupt Friedrich 《Structural chemistry》1998,9(3):209-214
The molecular structure of 1,3,5-tris (trimethylstannyl) benzene has been determined by gas-phase electron diffraction. The C — C bond length is in good agreement with that in benzene. In agreement with the somewhat electron-releasing character of the substituents, the endocyclic bond angles at the substituents are somewhat smaller than 120°. The mean value of Sn — C bond lengths is greater than that in tetraphenyltin and tetramethyltin. The SnMe3 groups appear freely rotating around the Caryl — Sn bonds. The following bond lengths (r
g) and bond angles were determined: (Sn — C)mean 2.150 ± 0.007 Å, C — C 1.399 ± 0.005 Å, (C — H)mean 1.105 ± 0.006 Å, < C — C(Sn) — C 117.7 ± 1.7º, < Caryl — Sn — Cmethyl 106.7 ± 0.7º < Sn — C — H 111.5 ± 0.9º. 相似文献
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Welter S Salluce N Benetti A Rot N Belser P Sonar P Grimsdale AC Müllen K Lutz M Spek AL De Cola L 《Inorganic chemistry》2005,44(13):4706-4718
In the search for light-addressable nanosized compounds we have synthesized 10 dinuclear homometallic trisbipyridyl complexes of linear structure with the general formula [M(bpy)3-BL-M(bpy)3]4+ [M = Ru(II) or Os(II); BL = polyphenylenes (2, 3, 4, or 5 units) or indenofluorene; bpy = 2,2'-bipyridine]. By using a "chemistry on the complex" approach, different sizes of rodlike systems have been obtained with a length of 19.8 and 32.5 A for the shortest and longest complex, respectively. For one of the ruthenium precursors, [Rubpy-ph2-Si(CH3)3][PF6]2, single crystals were obtained by recrystallization from methanol. Their photophysical and electrochemical properties are reported. All the compounds are luminescent both at room and low temperature with long excited-state lifetimes due to an extended delocalization. Nanosecond transient absorption showed that the lowest excited state involves the chelating unit attached to the bridging ligand. Electrochemical data indicated that the first reduction is at a slightly more positive potential than for the reference complexes [M(bpy)3]2+ (M = Ru, Os). This result confirms that the best acceptor is the bipyridine moiety connected to the conjugated spacers. The role of the tilt angle between the phenylene units, in the two series of complexes, for the ground and excited states is discussed. 相似文献
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Thomas O. Rot 《Archiv der Mathematik》2020,114(1):107-117
In this paper, we classify the homotopy classes of proper maps $$E\rightarrow \mathbb {R}^k$$, where E is a vector bundle over a compact Hausdorff space. As a corollary, we compute the homotopy classes of proper maps $$\mathbb {R}^n \rightarrow \mathbb {R}^k$$. We find a stability range of such maps. We conclude with some remarks on framed submanifolds of non-compact manifolds, the relationship with proper homotopy classes of maps, and the Pontryagin–Thom construction. 相似文献
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A compressive Fresnel holography approach is suggested for the recovery of partially occluded objects. Reconstruction guarantees are analyzed and the effectiveness of the method is demonstrated using simulations and an experimental result showing the reconstruction of a partially occluded resolution chart. 相似文献
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Thomas Rotärmel Dr. Pascal Specht Dr. Jonathan Becker Adam Neuba Prof. Dr. Siegfried Schindler 《欧洲无机化学杂志》2023,26(6):e202200626
In the active site of several copper monooxygenases, thioether residues are coordinated through the sulfur atom, e. g. dopamine-β-monooxygenase (DβM). The reaction of dioxygen with a series of copper(I) complexes with thioether groups in tripodal ligands based on either derivatives of tris(2-pyridylmethyl)amine (TMPA) or a guanidine system were investigated by low-temperature stopped-flow measurements. The formation of labile intermediates, an end-on superoxido complex, and μ-1,2-trans-peroxido copper(II) complexes were spectroscopically detected and a kinetic analysis allowed the calculation of activation parameters for these reactions supporting the postulated mechanism. Most interesting was the finding that replacing the ethyl group in the tren-guanidine derivative (TMGEt)2(SEtEt)N with a methyl group allowed a dramatic increase in the stability of the formed superoxido copper complex. Measurements with ozone were performed in order to find an alternative way to obtain and stabilize the labile intermediates. 相似文献
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