- Red-luminescent biphosphine stabilized 'Cu12S6' cluster molecules
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The synthesis, molecular structures and luminescence properties of two 'Cu12S6' cluster molecules with stabilizing bidentate phosphine ligands are described. Both display in the solid state at ambient temperature high photoluminescen
- Yang, Xiao-Xun,Issac, Ibrahim,Lebedkin, Sergej,Kühn, Michael,Weigend, Florian,Fenske, Dieter,Fuhr, Olaf,Eichh?fer, Andreas
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- Controlling gold nanoclusters by diphospine ligands
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We report the synthesis and structure determination of a new Au 22 nanocluster coordinated by six bidentate diphosphine ligands: 1,8-bis(diphenylphosphino) octane (L8 for short). Single crystal X-ray crystallography and electrospray ionization mass spectrometry show that the cluster assembly is neutral and can be formulated as Au22(L 8)6. The Au22 core consists of two Au 11 units clipped together by four L8 ligands, while the additional two ligands coordinate to each Au11 unit in a bidentate fashion. Eight gold atoms at the interface of the two Au11 units are not coordinated by any ligands. Four short gold-gold distances (2.64-2.65 A) are observed at the interface of the two Au11 clusters as a result of the clamping force of the four clipping ligands and strong electronic interactions. The eight uncoordinated surface gold atoms in the Au 22(L8)6 nanocluster are unprecedented in atom-precise gold nanoparticles and can be considered as potential in situ active sites for catalysis.
- Chen, Jing,Zhang, Qian-Fan,Bonaccorso, Timary A.,Williard, Paul G.,Wang, Lai-Sheng
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- Decarboxylative Phosphine Synthesis: Insights into the Catalytic, Autocatalytic, and Inhibitory Roles of Additives and Intermediates
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Phosphines are among the most widely used ligands, catalysts, and reagents. Current synthetic approaches to phosphines are dominated by nucleophilic displacement reactions with organometallic reagents. Here, we report a radical-based approach to phosphines that proceeds by a cross-electrophile coupling of chlorophosphines and redox-active esters. The reaction allows for the synthesis of a broad range of substituted phosphines that were not readily attainable with the present methods. Our experimental and DFT computational studies also clarified the catalytic, autocatalytic, and inhibitory roles of additives and intermediates, as well as the mechanistic details of the photocatalytic and zinc-mediated redox modes that can have implications for the mechanistic interpretation of other cross-electrophile coupling reactions.
- Jin, Shengfei,Haug, Graham C.,Nguyen, Vu T.,Flores-Hansen, Carsten,Arman, Hadi D.,Larionov, Oleg V.
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p. 9764 - 9774
(2019/10/14)
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- En Route to a Practical Primary Alcohol Deoxygenation
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A long-standing scientific challenge in the field of alcohol deoxygenation has been direct catalytic sp3 C-O defunctionalization with high selectivity and efficiency, in the presence of other functionalities, such as free hydroxyl groups and amines widely present in biological molecules. Previously, the selectivity issue had been only addressed by classic multistep deoxygenation strategies with stoichiometric reagents. Herein, we propose a catalytic late-transition-metal-catalyzed redox design, on the basis of dehydrogenation/Wolff-Kishner (WK) reduction, to simultaneously tackle the challenges regarding step economy and selectivity. The early development of our hypothesis focuses on an iridium-catalyzed process efficient mainly with activated alcohols, which dictates harsh reaction conditions and thus limits its synthetic utility. Later, a significant advancement has been made on aliphatic primary alcohol deoxygenation by employing a ruthenium complex, with good functional group tolerance and exclusive selectivity under practical reaction conditions. Its synthetic utility is further illustrated by excellent efficiency as well as complete chemo- and regio-selectivity in both simple and complex molecular settings. Mechanistic discussion is also included with experimental supports. Overall, our current method successfully addresses the aforementioned challenges in the pertinent field, providing a practical redox-based approach to the direct sp3 C-O defunctionalization of aliphatic primary alcohols.
- Dai, Xi-Jie,Li, Chao-Jun
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supporting information
p. 5433 - 5440
(2016/05/19)
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- Convenient and convergent syntheses of long-chain α,ω-dibromides and diphosphines of the formula X(CH2)nX (n = 18-32)
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The known tetrahydropyranyl ethers Br(CH2)yOTHP (y = 6, 9, 11), which are easily prepared from commercial bromoalcohols, are sequentially treated with Mg, Li2CuCl4, and X(CH2)2X (z/X = 6/Br, 7/Br, 8/Br, 10/Br, 10/I) to give the diethers THPO(CH2)nOTHP in 68-40% yields (n = 2 y + z = 18, 19, 20, 22, 24, 28, 32). Subsequent reactions with Ph3P and 2,4,4,6-tetrabromocyclohexa-2,5-dienone give the title compounds Br(CH2)nBr in 91-75% yields. Reactions with commercial K+PPh2 give the diphosphines Ph2P(CH2)nPPh2 in 95-74% yields.
- Mohr, Wolfgang,Horn, Clemens R.,Stahl, Juergen,Gladysz
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p. 1279 - 1285
(2007/10/03)
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- Preparation of organohalosilanes
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When oganohalosilanes are prepared by charging a reactor with a contact mass containing a metallic silicon powder and a copper catalyst, and introducing an organohalide-containing gas into the reactor to effect the direct reaction, a poly(organo)phosphino compound is added to the contact mass. The invention is successful in producing organohalosilanes at a significantly improved production rate without reducing the selectivity of useful silane.
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