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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(9):2390-2395
Reactions of ZnI2L2 (where L=[HC(PPh2NPh)]−) with solutions of the Zintl phase K4Ge9 in liquid ammonia lead to retention of the Zn−Zn bond and formation of the anion [(η4‐Ge9)Zn−Zn(η4‐Ge9)]6−, representing the first complex with a Zn−Zn unit carrying two cluster entities. The trimeric anion [(η4‐Ge9)Zn{μ2(η1:η1Ge9)}Zn(η4‐Ge9)]8− forms as a side product, indicating that oxidation reactions also take place. The reaction of Zn2Cp*2 (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) with K4Ge9 in ethylenediamine yielded the linear polymeric unit {[Zn[μ2(η4:η1Ge9)]}2− with the first head‐to‐tail arrangement of ten‐atom closo ‐clusters. All anions were obtained and structurally characterized as [A (2.2.2‐crypt)]+ salts (A =K, Rb). Copious computational analyses at a DFT‐PBE0/def2‐TZVPP/PCM level of theory confirm the experimental structures and support the stability of the two hypothetical ten vertex cluster fragments closo ‐[Ge9Zn]2− and (paramagnetic) [Ge9Zn]3−. 相似文献
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The compound [K(18‐crown‐6)]8[Ge9=Ge9=Ge9=Ge9] ˙ 8en ( 1 ) featuring a [Ge9=Ge9=Ge9=Ge9]8‐cluster anion was synthesized from K4Ge9 for the first time. The X‐ray single crystal analysis shows that, in many respects such as bond connection and packing style, compound 1 is quite different from the previously reported compounds [Rb(18‐crown‐6)]8[Ge9=Ge9=Ge9=Ge9] ˙ 2en ( 2 ) and [Rb(18‐crown‐6)]8[Ge9=Ge9=Ge9=Ge9] ˙ 6en ( 3 ). Crystal packing of 1 gives strong indications that the highly charged nano‐rods self assembly in a hexagonal rod packing. 相似文献
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Linking Deltahedral Zintl Clusters with Conjugated Organic Building Blocks: Synthesis and Characterization of the Zintl Triad [R‐Ge9‐CHCHCHCH‐Ge9‐R]4− 下载免费PDF全文
Manuel M. Bentlohner Dr. Wilhelm Klein Dr. Zohreh H. Fard Laura‐Alice Jantke Prof. Dr. Thomas F. Fässler 《Angewandte Chemie (International ed. in English)》2015,54(12):3748-3753
The accessibility of triads with deltahedral Zintl clusters in analogy to fullerene–linker–fullerene triads is another example for the close relationship between fullerenes and Zintl clusters. The compound {[K(2.2.2‐crypt)]4[RGe9‐CH?CH? CH?CH‐Ge9R]}(toluene)2 (R=(2Z,4E)‐7‐amino‐5‐aza‐hepta‐2,4‐dien‐2‐yl), containing two deltahedral [Ge9] clusters linked by a conjugated (1Z,3Z)‐buta‐1,3‐dien‐1,4‐diyl bridge, was synthesized through the reaction of 1,4‐bis(trimethylsilyl)butadiyne with K4Ge9 in ethylenediamine and crystallized after the addition of 2.2.2‐cryptand and toluene. The compound was characterized by single‐crystal structure analysis as well asNMR and IR spectroscopy. 相似文献
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Hong‐Lei Xu Ivan A. Popov Nikolay V. Tkachenko Zi‐Chuan Wang Alvaro Muoz‐Castro Alexander I. Boldyrev Zhong‐Ming Sun 《Angewandte Chemie (International ed. in English)》2020,59(39):17286-17290
In this work, the largest heterometallic supertetrahedral clusters, [Zn6Ge16]4? and [Cd6Ge16]4?, were directly self‐assembled through highly‐charged [Ge4]4? units and transition metal cations, in which 3‐center–2‐electron σ bonding in Ge2Zn or Ge2Cd triangles plays a vital role in the stabilization of the whole structure. The cluster structures have an open framework with a large central cavity of diameter 4.6 Å for Zn and 5.0 Å for Cd, respectively. Time‐dependent HRESI‐MS spectra show that the larger clusters grow from smaller components with a single [Ge4]4? and ZnMes2 units. Calculations performed at the DFT level indicate a very large HOMO–LUMO energy gap in [M6Ge16]4? (2.22 eV), suggesting high kinetic stability that may offer opportunities in materials science. These observations offer a new strategy for the assembly of heterometallic clusters with high symmetry. 相似文献
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Concise Syntheses of bis‐Strychnos Alkaloids (−)‐Sungucine, (−)‐Isosungucine,and (−)‐Strychnogucine B from (−)‐Strychnine 下载免费PDF全文
Dr. Senzhi Zhao Christiana N. Teijaro Heng Chen Dr. Gopal Sirasani Dr. Shivaiah Vaddypally Prof. Dr. Michael J. Zdilla Prof. Dr. Graham E. Dobereiner Prof. Dr. Rodrigo B. Andrade 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11593-11596
The first chemical syntheses of complex, bis‐Strychnos alkaloids (?)‐sungucine ( 1 ), (?)‐isosungucine ( 2 ), and (?)‐strychnogucine B ( 3 ) from (?)‐strychnine ( 4 ) is reported. Key steps included (1) the Polonovski–Potier activation of strychnine N‐oxide; (2) a biomimetic Mannich coupling to forge the signature C23?C5′ bond that joins two monoterpene indole monomers; and (3) a sequential HBr/NaBH3CN‐mediated reduction to fashion the ethylidene moieties in 1 – 3 . DFT calculations were employed to rationalize the regiochemical course of reactions involving strychnine congeners. 相似文献
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Bin Zhou Yedi Xing Prof. Shu Miao Prof. Mingrun Li Prof. Wen‐Hua Zhang Prof. Can Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12426-12431
A facile colloidal approach to synthesize Ag8(Ge1?x,Snx)(S6?y,Sey) nanocrystals (NCs) in a highly controlled way across the entire compositional ranges (0≤x≤1, 0≤y≤6) has been developed. The NCs exhibit a uniform size distribution, highly crystalline structure, over 1 g scalable synthesis, and tunable band gaps in the range of 0.88–1.45 eV by varying their chemical compositions. The Ag8GeS6 NCs with a band gap of approximately 1.45 eV were employed as a model light harvester to assess their applicability in solar cells by a full solution‐processing device, yielding an efficiency of 0.28 % under AM1.5 illumination, demonstrating their application potential in solar energy utilization. 相似文献
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Xiaobei Wang Dongliang Xia Ling Tan Huan Chen Hongxiu Huang Dr. Hao Song Prof. Dr. Yong Qin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(41):14602-14607
Total syntheses of (?)‐isoschizogamine and (?)‐2‐hydroxyisoschizogamine are described. The synthesis employs two asymmetric Michael additions to establish chiral centers at C7 and the quaternary carbon C20. Regioselective reduction of the methylthioiminium cation rather than the enamine generates an isoschizogamine‐type pentacyclic skeleton. Acidic hydrolysis of the isoschizogamine‐type intermediate in the absence of oxygen provides natural (?)‐isoschizogamine. Conducting the reaction in the presence of oxygen leads to a multistep oxidative hydrolysis cascade that affords unnatural (?)‐2‐hydroxyisoschizogamine. 相似文献
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Bo Xu Wen Xun Shaobin Su Hongbin Zhai 《Angewandte Chemie (International ed. in English)》2020,59(38):16475-16479
Cyclopianes are novel diterpenes featuring a highly strained 6/5/5/5 tetracyclic core embedded with 6–8 consecutive stereocenters. The concise total syntheses of (?)‐conidiogenone B, (?)‐conidiogenone, and (?)‐conidiogenol have been accomplished in 14–17 steps. The present work features a HAT‐mediated alkene–nitrile cyclization to access the cis‐biquinane, a Nicholas/Pauson–Khand reaction to construct the linear triquinane, and a Danheiser annulation to afford the congested angular triquinane skeleton. 相似文献
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