共查询到20条相似文献,搜索用时 15 毫秒
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Ying‐Hao Lo Franois P. Gabbaï 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10300-10303
With the intent to demonstrate that the charge of Z‐type ligands can be used to modulate the electrophilic character and catalytic properties of coordinated transition metals, we are now targeting complexes bearing polycationic antimony‐based Z‐type ligands. Toward this end, the dangling phosphine arm of ((o‐(Ph2P)C6H4)3)SbCl2AuCl ( 1 ) was oxidized with hydrogen peroxide to afford [((o‐(Ph2P)C6H4)2(o‐Ph2PO)C6H4)SbAuCl2]+ ([ 2 a ]+) which was readily converted into the dicationic complex [((o‐(Ph2P)C6H4)2(o‐Ph2PO)C6H4)SbAuCl]2+ ([ 3 ]2+) by treatment with 2 equiv AgNTf2. Both experimental and computational results show that [ 3 ]2+ possess a strong Au→Sb interaction reinforced by the dicationic character of the antimony center. The gold‐bound chloride anion of [ 3 ]2+ is rather inert and necessitates the addition of excess AgNTf2 to undergo activation. The activated complex, referred to as [ 4 ]2+ [((o‐(Ph2P)C6H4)2(o‐Ph2PO)C6H4)SbAuNTf2]2+ readily catalyzes both the polymerization and the hydroamination of styrene. This atypical reactivity underscores the strong σ‐accepting properties of the dicationic antimony ligand and its activating impact on the gold center. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(32):10388-10392
A molecularly defined chiral boxmi iron alkyl complex catalyzes the hydroboration of various functionalized ketones and provides the corresponding chiral halohydrines, oxaheterocycles (oxiranes, oxetanes, tetrahydrofurans, and dioxanes) and amino alcohols with excellent enantioselectivities (up to >99 %ee) and conversion efficiencies at low catalyst loadings (as low as 0.5 mol %). Turnover frequencies of greater than 40000 h−1 at −30 °C highlight the activity of this earth‐abundant metal catalyst which tolerates a large number of functional groups. 相似文献
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Katherine M. Marczenko Joseph A. Zurakowski Karlee L. Bamford Joshua W. M. MacMillan Saurabh S. Chitnis 《Angewandte Chemie (International ed. in English)》2019,58(50):18096-18101
A rigid naphthalenediamine framework has been used to prepare antimony hydrides that feature LUMO shapes and energies similar to those found in secondary boranes. By exploiting this feature, we introduce the first examples of uncatalyzed hydrostibination reactions of robust C≡C, C=C, C=O, and N=N bonds as new elementary hydrometalation reactions analogous to hydroboration. These results endorse the notion of a diagonal relationship between the lightest p‐block element and the heaviest Group 15 elements and may lead to the conception of novel reaction chemistry. 相似文献
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James S. Jones Casey R. Wade Franois P. Gabbaï 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(34):9022-9025
According to the covalent bond classification (CBC) method, two‐electron donors are defined as L‐type ligands, one‐electron donors as X‐type ligands, and two‐electron acceptors as Z‐type ligands. These three ligand functions are usually associated to the nature of the ligating atom, with phosphine, alkyl, and borane groups being prototypical examples of L‐, X‐ and Z‐ligands, respectively. A new SbNi platform is reported in which the ligating Sb atom can assume all three CBC ligand functions. Using both experimental and computational data, it is shown that PhICl2 oxidation of (o‐(Ph2P)C6H4)3SbNi(PPh3) ( 1 ) into [(o‐(Ph2P)C6H4)3ClSb]NiCl ( 2 ) is accompanied by a conversion of the stibine L‐type ligand of 1 into a stiboranyl X‐type ligand in 2 . Furthermore, the reaction of 2 with the catecholate dianion in the presence of cyclohexyl isocyanide results in the formation of [(o‐(Ph2P)C6H4)3(o‐O2C6H4Sb)]Ni(CNCy) ( 4 ), a complex featuring a nickel atom coordinated by a Lewis acidic, Z‐type, stiborane ligand. 相似文献
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Chao Liu Nikolay V. Tkachenko Ivan A. Popov Nikita Fedik Xue Min Cong‐Qiao Xu Jun Li John E. McGrady Alexander I. Boldyrev Zhong‐Ming Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(25):8455-8459
We report the characterization of the compound [K([2.2.2]crypt)]4[In8Sb13], which proves to contain a 1:1 mixture of [Sb@In8Sb12]3? and [Sb@In8Sb12]5?. The tri‐anion displays perfect Th symmetry, the first completely inorganic molecule to do so, and contains eight equivalent In3+ centers in a cube. The gas‐phase potential energy surface of the penta‐anion has eight equivalent minima where the extra pair of electrons is localized on one In+ center, and these minima are linked by low‐lying transition states where the electron pair is delocalized over two adjacent centers. The best fit to the electron density is obtained from a model where the structure of the 5? cluster lies close to the gas‐phase transition state. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7557-7561
Ligand development for rhodium(III)‐catalyzed C−H activation reactions has largely been limited to cyclopentadienyl (Cp) based scaffolds. 2‐Methylquinoline has now been identified as a feasible ligand that can coordinate to the metal center of Cp*RhCl to accelerate the cleavage of the C−H bond of N ‐pentafluorophenylbenzamides, providing a new structural lead for ligand design. The compatibility of this reaction with secondary free amines and anilines also overcomes the limitations of palladium(II)‐catalyzed C−H amination reactions. 相似文献
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Andrew J. Bochat Veronika M. Shoba James M. Takacs 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9534-9538
Regiocontrol in the rhodium‐catalyzed boration of vinyl arenes is typically dominated by the presence of the conjugated aryl substituent. However, small differences in TADDOL‐derived chiral monophosphite ligands can override this effect and direct rhodium‐catalyzed hydroboration of β‐aryl and β‐heteroaryl methylidenes by pinacolborane to selectively produce either chiral primary or tertiary borated products. The regiodivergent behavior is coupled with enantiodivergent addition of the borane. The nature of the TADDOL backbone substituents and that of the phosphite moiety function synergistically to direct the sense and extent of regioselectivity and enantioinduction. Twenty substrates are shown to undergo each reaction mode with regioselectivity values reaching greater than 20:1 and enantiomer ratios reaching up to 98:2. A variety of subsequent transformations illustrate the potential utility of each product. 相似文献
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Zhen Yang Sheng Jiang Feng Li Yatao Qiu Jianhua Gu Roderic I. Pettigrew Mauro Ferrari Dale J. Hamilton Zheng Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5326-5330
Interaction of multiple entities and receptors, or multivalency is widely applied to achieve high affinity ligands for diagnostic and therapeutic purposes. However, lack of knowledge on receptor distribution in living subjects remains a challenge for rational structure design. Herein, we develop a force measurement platform to probe the distribution and separation of the cell surface vascular endothelial growth factor receptors (VEGFR) in live cells, and use this to assess the geometry of appropriate linkers for distinct multivalent binding modes. A tetravalent lead ZD‐4, which was developed from an antitumor drug ZD6474 (Vandetanib) with combined hybrid binding effects, yielded a 2000‐fold improvement in the binding affinity to VEGFR with IC50 value of 25 pm . We confirmed the improved affinity by the associated increase of tumor uptake in the VEGFR‐targeting positron emission tomography (PET) imaging using U87 tumor xenograft mouse model. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(36):10915-10919
The reduction of UVI uranyl halides or amides with simple LnII or UIII salts forms highly symmetric, linear, oxo‐bridged trinuclear UV/LnIII/UV, LnIII/UIV/LnIII, and UIV/UIV/UIV complexes or linear LnIII/UV polymers depending on the stoichiometry and solvent. The reactions can be tuned to give the products of one‐ or two‐electron uranyl reduction. The reactivity and magnetism of these compounds are discussed in the context of using a series of strongly oxo‐coupled homo‐ and heterometallic poly(f‐block) chains to better understand fundamental electronic structure in the f‐block. 相似文献
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Jillian S. K. Clark Michael J. Ferguson Robert McDonald Mark Stradiotto 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6457-6461
Base‐metal catalysts capable of enabling the assembly of heteroatom‐dense molecules by cross‐coupling of primary heteroarylamines and (hetero)aryl chlorides, while sought‐after given the ubiquity of unsymmetrical di(hetero)arylamino fragments in pharmacophores, are unknown. Herein, we disclose the new “double cage” bisphosphine PAd2‐DalPhos ( L2 ). The derived air‐stable NiII pre‐catalyst C2 functions well at low loadings in challenging test C?N cross‐couplings with established substrates, and facilitates the first Ni‐catalyzed C?N cross‐couplings of primary five‐ or six‐membered ring heteroarylamines and activated (hetero)aryl chlorides, with synthetically useful scope that is competitive with Pd catalysis. 相似文献