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排序方式: 共有321条查询结果,搜索用时 437 毫秒
31.
Bastiaan Kooij Paul Varava Farzaneh Fadaei-Tirani Rosario Scopelliti Dimitrios A. Pantazis Gerard P. Van Trieste III David C. Powers Kay Severin 《Angewandte Chemie (International ed. in English)》2023,62(4):e202214899
Homometallic copper complexes with alkenylidene ligands are discussed as intermediates in catalysis but the isolation of such complexes has remained elusive. Herein, we report the structural characterization of copper complexes with bridging and terminal alkenylidene ligands. The compounds were obtained by irradiation of CuI complexes with N-heterocyclic diazoolefin ligands. The complex with a terminal alkenylidene ligand required isolation in a crystalline matrix, and its structural characterization was enabled by in crystallo photolysis at low temperature. 相似文献
32.
Roman Bashkurov Dr. Alexander Kaushansky Dr. Boris Tumanskii Dr. Natalia Fridman Dr. Dmitry Bravo-Zhivotovskii Prof. Dr. Yitzhak Apeloig 《Angewandte Chemie (International ed. in English)》2023,62(18):e202300847
Thermolysis of a 1 : 1 mixture of tris(di-tert-butylmethylsilyl)germane 9 and bis(di-tert-butylmethylsilyl)germane 17 at 100 °C produces unexpectedly octagermacubane 18 , having two 3-coordinate Ge0 atoms (40 % yield). 18 was characterized by X-ray crystallography and it is a singlet biradical (according to DFT quantum mechanical calculations and the absence of an EPR signal). Reactions of 18 with CH2Cl2 and H2O yield the novel dichloro-octagermacubane 24 and hydroxy-octagermacubane 25 , respectively. Reduction of 18 with tBuMe2SiNa in THF produces an isolable octagermacubane radical anion 26-Na . Based on X-ray crystallography, EPR spectroscopy and DFT quantum mechanical calculations, 26-Na is classified as a Ge-centered radical anion. 相似文献
33.
Dr. Yinxiang Zeng Zhihao Pei Dr. Yan Guo Dr. Deyan Luan Prof. Xiaojun Gu Prof. Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2023,62(45):e202312145
Constructing multifunctional interphases to suppress the rampant Zn dendrite growth and detrimental side reactions is crucial for Zn anodes. Herein, a phytic acid (PA)-ZnAl coordination compound is demonstrated as a versatile interphase layer to stabilize Zn anodes. The zincophilic PA-ZnAl layer can manipulate Zn2+ flux and promote rapid desolvation kinetics, ensuring the uniform Zn deposition with dendrite-free morphology. Moreover, the robust PA-ZnAl protective layer can effectively inhibit the hydrogen evolution reaction and formation of byproducts, further contributing to the reversible Zn plating/stripping with high Coulombic efficiency. As a result, the Zn@PA-ZnAl electrode shows a lower Zn nucleation overpotential and higher Zn2+ transference number compared with bare Zn. The Zn@PA-ZnAl symmetric cell exhibits a prolonged lifespan of 650 h tested at 5 mA cm−2 and 5 mAh cm−2. Furthermore, the assembled Zn battery full cell based on this Zn@PA-ZnAl anode also delivers decent cycling stability even under harsh conditions. 相似文献
34.
Yapei Gao Zheming Liu Dr. Tao Li Prof. Wanxiang Zhao 《Angewandte Chemie (International ed. in English)》2023,62(49):e202314006
Mixed-valence (MV) dimers have been extensively investigated, however, the structure and properties of purely organic MV trimers based on open-shell polycyclic aromatic hydrocarbons remain elusive. Herein, unprecedented MV BN-doped corannulene radical cations [ BN-Cor1 ]3⋅⋅2+ ⋅ 2[BArylF4]− and [ BN-Cor2 ]3⋅⋅2+ ⋅ 2[BArylF4]− were synthesized via chemical oxidation, and their structures were unambiguously confirmed by single-crystal X-ray diffraction. These uncommon radical cations consist of three corannulene cores and two [BArylF4]− anions, and three corannulene motifs [ BN-Cor1 ]3⋅⋅2+ and [ BN-Cor2 ]3⋅⋅2+ in the unit cell exhibit a trimer structure with a slipped π-stacking configuration. Detailed structural analyses further revealed that the corannulene cores exhibit an infinite layered self-assembly configuration, allowing their potential applications as building blocks for molecular conductors. The detection of a forbidden transition (Δms=±2) by electron paramagnetic resonance (EPR) spectroscopy further confirmed the existence of two unpaired electrons in the π-trimers and the MV characteristic of these two species. Variable-temperature EPR and conductivity measurements suggested that the BN-doped π-trimers exhibited antiferromagnetic coupling and conductivity properties. 相似文献
35.
Hongyuan Zhao Qiujie Wang Ziying Wen Haibo Sun Sujun Ji Xuan Meng Ruiling Zhang Junke Jiang Zhe Tang Feng Liu 《Angewandte Chemie (International ed. in English)》2023,62(52):e202316336
The achievement of significant photoluminescence (PL) in lanthanide ions (Ln3+) has primarily relied on host sensitization, where energy is transferred from the excited host material to the Ln3+ ions. However, this luminous mechanism involves only one optical antenna, namely the host material, which limits the accessibility of excitation wavelength-dependent (Ex-De) PL. Consequently, the wider application of Ln3+ ions in light-emitting devices is hindered. In this study, we present an organic–inorganic compound, (DMA)4LnCl7 (DMA+=[CH3NH2CH3]+, Ln3+=Ce3+, Tb3+), which serves as an independent host lattice material for efficient Ex-De emission by doping it with trivalent antimony (Sb3+). The pristine (DMA)4LnCl7 compounds exhibit high luminescence, maintaining the characteristic sharp emission bands of Ln3+ and demonstrating a high PL quantum yield of 90–100 %. Upon Sb3+ doping, the compound exhibits noticeable Ex-De emission with switchable colors. Through a detailed spectral study, we observe that the prominent energy transfer process observed in traditional host-sensitized systems is absent in these materials. Instead, they exhibit two independent emission centers from Ln3+ and Sb3+, each displaying distinct features in luminous color and radiative lifetime. These findings open up new possibilities for designing Ex-De emitters based on Ln3+ ions. 相似文献
36.
采用共沉淀法合成了掺杂 L a、 Gd、 Y的 Tb-邻氨基苯甲酸配合物 ,研究其荧光性能 ,结果显示 ,掺杂L a、Gd、Y后 ,对 Tb配合物的发光有增敏作用 ,讨论了不同的掺杂离子 (L a、Gd、Y)及掺杂量对其荧光性能的影响。发现 ,当掺杂离子取代大部分 Tb3+时 ,其发光增强仍十分显著。 相似文献
37.
Synthesis and Crystal Structures of the Zinc Amido Complexes [Zn(NPh2)2]2 and [Zn(NPh2)2(THF)2] Zinc diphenylamide is prepared from Zn[N(SiMe3)2]2 and diphenylamine by transamination reaction. The compound is characterized by a crystal structure analysis. According to it [Zn(NPh2)2]2 forms centrosymmetric dimeric molecules with Zn–N distances of 185.9 pm for the terminally bonded NPh2– ligand and Zn–N distances of 204.0 and 202.6 pm in the four-membered ring. From tetrahydrofuran solutions [Zn(NPh2)2(THF)2] crystallizes as monomeric molecular complex with Zn–N bond lengths of 192.2 pm in average. 相似文献
38.
The magnesium transition metal stannides MgRuSn4 and MgxRh3Sn7—x (x = 0.98—1.55) were synthesized from the elements in glassy carbon crucibles in a water‐cooled sample chamber of a high‐frequency furnace. They were characterized by X‐ray diffraction on powders and single crystals. MgRuSn4 adopts an ordered PdGa5 type structure: I4/mcm, a = 674.7(1), c = 1118.1(2) pm, wR2 = 0.0506, 515 F2 values and 12 variable parameters. The ruthenium atoms have a square‐antiprismatic tin coordination with Ru—Sn distances of 284 pm. These [RuSn8/2] antiprisms are condensed via common faces forming two‐dimensional networks. The magnesium atoms fill square‐prismatic cavities between adjacent [RuSn4] layers with Mg—Sn distances of 299 pm. The rhodium based stannides MgxRh3Sn7—x crystallize with the cubic Ir3Ge7 type structure, space groupe Im3m. The structures of four single crystals with x = 0.98, 1.17, 1.36, and 1.55 have been refined from X‐ray diffractometer data. With increasing tin substitution the a lattice parameter decreases from 932.3(1) pm for x = 0.98 to 929.49(6) pm for x = 1.55. The rhodium atoms have a square antiprismatic tin/magnesium coordination. Mixed Sn/Mg occupancies have been observed for both tin sites but to a larger extend for the 12d Sn2 site. Chemical bonding in MgRuSn4 and MgxRh3Sn7—x is briefly discussed. 相似文献
39.
The Reaction of Dialkylaluminium Chlorides with Bis(trimethylsilyl)hydrazine: Formation of the Adducts R2AlCl · NH2NHSiMe3 Containing the Unstable Monotrimethylsilylhydrazine Bis(trimethylsilyl)hydrazine did not react with dialkylaluminium chlorides R2AlCl [R = CH2CMe3, CMe3 and CH(SiMe3)2] by the formation of trimethylchlorosilane, but by dismutation to yield tris(trimethylsilyl)hydrazine and trimethylsilylhydrazine. The unstable, sterically less shielded NH2NHSiMe3 was stabilized by the coordination to the coordinatively unsaturated aluminium compounds. The adducts R2AlCl · NH2NHSiMe3 were formed, which were characterized by crystal structure determinations with R = CMe3 and CH(SiMe3)2. In all cases, the hydrazine derivative binds to the aluminium atoms via the more basic NH2 nitrogen atom. The adduct Me3CAlCl2 · NH2N(SiMe3)2 containing intact 1,1‐bis(trimethylsilyl)hydrazine as a ligand was isolated in a trace amount and also characterized by a crystal structure determination. 相似文献
40.
Unusual Reactivity of the Silicon-Phosphorus Double Bond in a Silylidene(fluorosilyl)phosphane: Intramolecular C, H Insertion and its Conversion in a New Silylidene(silyl)phosphane Thermolysis of the (fluoro-tert.butyl-2,4,6-triisopropylphenylsilyl)-tert.butyl-2,4,6-triisopropylphenylsilylidenephosphane (“Phosphasilene”) ( 1 ) in toluene at 130 °C leads, under C,H-activation of a methyl group of a ortho-isopropyl group, to the constitutional isomeric silyl(fluorosilyl)phosphane ( 2 ), whose structure has been crystallographically established. It crystallizes racemically and possesses a benzosilacyclopent-2-ene moiety as major structural motif. Lithiation of 2 leads to the corresponding lithium phosphanide ( 3 ), which eliminates LiF at 80 °C in toluene and, concomitantly, furnishes the colorless new silylidene(silyl)phosphane ( 4 ) in the form of its two diasteromers (Z : E ca. 1 : 2). The 31P NMR chemical shifts of δ = –29.95 and –31.75 are practically identical with the value of 1 , and the 29Si NMR spectrum shows resonance signals at characteristically low field (δ = 222.5 (1J(Si, P) = 160 Hz), 221.8 (1J(Si, P) = 161 Hz)). An single-crystal X-ray diffraction analysis of an enantiomeric form of the E-isomer reveals a Si=P distance of 2.063(2) Å, whereas the Si–P single bond distance of 2.246(2) Å is ca. 8% longer. The low coordinated silicon center is trigonal planar surrounded and the Si–P–Si angle is 108.09(8)°. 相似文献