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41.
Alexander Pöcheim Dr. Gül Altınbaş Özpınar Prof. Dr. Thomas Müller Dr. Judith Baumgartner Prof. Dr. Christoph Marschner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(71):17252-17260
Reaction of a 2,5-dilithiated silole with excess dichlorodimethylsilane gives the respective 2,5-bis(chlorodimethylsilyl) substituted silole. This compound can be converted to 2,5-bis(oligosilanyl) substituted siloles by addition of a suitable oligosilanide. In the UV spectra of the thus obtained compounds the lowest energy absorptions are bathochromically shifted compared to the absorptions of the two constituents, namely the 2,5-disilyl substituted silole and a trisilane. The bathochromic shift is interpreted as being caused by a mixed σ-conjugation/cross-hyperconjugation. This assumption is supported by TD-DFT calculations, which show a significant contribution from Si−Si bonds to the HOMO of the molecule. 相似文献
42.
Xiaojing Liu Mariana Kozlowska Timur Okkali Danny Wagner Tomohiro Higashino Gerald Brenner‐Weiß Stefan M. Marschner Zhihua Fu Qiang Zhang Hiroshi Imahori Stefan Brse Wolfgang Wenzel Christof Wll Lars Heinke 《Angewandte Chemie (International ed. in English)》2019,58(28):9590-9595
Photoconductivity is a characteristic property of semi‐conductors. Herein, we present a photo‐conducting crystalline metal–organic framework (MOF) thin film with an on–off photocurrent ratio of two orders of magnitude. These oriented, surface‐mounted MOF thin films (SURMOFs), contain porphyrin in the framework backbone and C60 guests, loaded in the pores using a layer‐by‐layer process. By comparison with results obtained for reference MOF structures and based on DFT calculations, we conclude that donor–acceptor interactions between the porphyrin of the host MOF and the C60 guests give rise to a rapid charge separation. Subsequently, holes and electrons are transported through separate channels formed by porphyrin and by C60, respectively. The ability to tune the properties and energy levels of the porphyrin and fullerene, along with the controlled organization of donor–acceptor pairs in this regular framework offers potential to increase the photoconduction on–off ratio. 相似文献
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44.
Fischer R Baumgartner J Kickelbick G Hassler K Marschner C 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(4):1021-1030
By reaction of the hexabromoheptasilane MeSi(SiMe(2)SiMeBr(2))(3) (1 a) with H(2)O, H(2)S, NH(3), and H(2)NMe the heptasilaadamantanes MeSi(SiMe(2)SiMeO)(3) (4), MeSi(SiMe(2)SiMeS)(3) (5), MeSi(SiMe(2)SiMeNH)(3) (6 a), and MeSi(SiMe(2)SiMeNMe)(3) (6 b), respectively, were prepared in good to moderate yields. Molecular structures of 4, 5, 6 a, and 6 b were determined by X-ray crystallography. The symmetry of the cages is approximately C(3v), and the geometry around the nitrogen atoms is essentially planar. Ab initio SCF/HF calculations with the 6-31G* basis set confirm these results. Reduction of MeSi(SiMe(2)SitBuBr(2))(3) (1 b) with lithium naphthalenide afforded the heptasilanortricyclene MeSi(SiMe(2)SitBu)(3) (7). The (29)Si NMR spectrum of 7 consists of three signals with chemical shifts that agree closely with values predicted by ab initio calculations. (29)Si INADEQUATE spectra also strongly support the nortricyclene structure. Ab initio SCF/HF calculations were performed for the parent molecule Si(7)H(10), and the ring strain of the cage was estimated as 168.8 kJ mol(-1) by using the homodesmic reaction Si(7)H(10) + 3 Si(2)H(6)-->Si(13)H(28). Compound 1 a also served as the starting material for the preparation of first-generation dendrimer 2 a by reaction with six equivalents of Ph(2)MeSiLi. Subsequent protodearylation with HBr and reaction with (Me(2)PhSi)(2)SiMeK afforded second-generation dendrimer 3. All dendrimers were characterized by multinuclear NMR spectroscopy. 相似文献
45.
M. Markina K. Klimov A. N. Vasiliev A. Freimut K. Kordonis M. Kreiner T. Lorentz T. Yamauchi Y. Ueda 《JETP Letters》2004,79(11):542-544
The thermal properties—specific heat, thermal conductivity, and thermal expansion coefficients—of a single crystal of quasi-one-dimensional variable-valence β-Na0.33V2O5 compound were studied. With lowering temperature, it sequentially undergoes the structural (T S ~ 230 K), charge (T C ~ 136 K), and magnetic (T N ~ 22 K) phase transitions. The structural transition at T S , resulting in the ordering of the Na ions, and the charge ordering at T C , resulting in the charge redistribution over the positions of V ions, are accompanied by the anomalies in the temperature dependences of all the studied properties. The magnetic ordering at T N results in the appearance of the canted antiferromagnetic structure and manifests itself only in the anomaly in the temperature dependences of the thermal expansion coefficients. 相似文献
46.
Deeken S Proch S Casini E Braun HF Mechtler C Marschner C Motz G Kempe R 《Inorganic chemistry》2006,45(4):1871-1879
(4-Methyl-pyridin-2-yl)(trimethylsilanyl)amine (ApSi-H) and tert-butyl(4-methyl-pyridin-2-yl)amine (AptBu-H) were synthesized via salt metathesis and aryl amination reactions, respectively. Lithiation of these two aminopyridines using n-BuLi and the reactions with [(dme)NiCl2] (dme = dimethoxyethane) or [(cod)PdCl2] (cod = cyclooctadiene) in THF at low temperature gave rise--after workup in hexane--to group 10 amido compounds, [(ApSi)4Ni2], [(AptBu)2Pd], [(AptBu-H)(AptBu)2Ni], [(AptBu)3(C2H5O)3Ni3OLi(thf)], and [(AptBu)2Ni(tBupy)2] (tBupy = 4-tert-butylpyridine). The aminopyridinato complexes were characterized by X-ray crystal structure analysis. The highly strained binding situation of the aminopyridinato ligands suggested that these compounds might be efficiently converted into catalytically active species. The applications of some of the synthesized complexes as Suzuki cross-coupling catalysts (activation of aryl chlorides) are described and [(ApSi)4Ni2] is a rare example of a "phosphine-free" catalyst system. A number of late transition metal complexes were found to successfully catalyze polymerization of MeH2SiSiH2Me toward soluble, linear poly(methylsilane). Remarkable activity was observed for [(ApSi)2Pd]. 相似文献
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49.
F. Marschner 《Tetrahedron》1975,31(18):2303-2308
By optimized PPP-SCF-CI-parameters and the conception of partial bond- and charge-localizing on the basis of a structural model of benzene the PE- and UV-spectroscopical dates of Fluor-, Chlor-, Brom-, Jodbenzene, Thiophenol, Toluene, Phenol and Aniline are interpreted within the error-limit of experimental values. By the influence of substituents on the π-e1g(a)-orbital of benzene it is demonstrated, that the rigid use of Koopmans-Theorem cannot be presupposed, if n-orbitals are insufficient delocalized. Therefore the differences from Koopmans-Theorem are the greatest in Fluorbenzene and decrease with increasing donor-character. They are also significant in Aniline. The examination of this differences with the aid of the model-conception permits statements of two significant effects: (1) bond-length-changes and (2) orbital-decontraction or—contraction (changes in the effective nuclear charge number) caused by ionisation or excitation. Both effects are reverse. The second effect dominates in the examined compounds and causes changes in MO-energy on an average of - 0·333 [eV] (3·65%). 相似文献
50.
Fischer R Zirngast M Flock M Baumgartner J Marschner C 《Journal of the American Chemical Society》2005,127(1):70-71
Reaction of the magnesium transmetalation product of a 1,2-dipotassiodisilane with hafnocene dichloride gives a disilene hafnocene complex. X-ray crystallography of the respective trimethylphosphane adduct provides structural proof for this assignment. 相似文献