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Kyle A. Mandla Michael L. Neville Curtis E. Moore Arnold L. Rheingold Joshua S. Figueroa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(43):15473-15477
Relative to other cyclic poly‐phosphorus species (that is, cyclo‐Pn), the planar cyclo‐P4 group is unique in its requirement of two additional electrons to achieve aromaticity. These electrons are supplied from one or more metal centers. However, the degree of charge transfer is dependent on the nature of the metal fragment. Unique examples of dianionic mononuclear η4‐P4 complexes are presented that can be viewed as the simple coordination of the [cyclo‐P4]2? dianion to a neutral metal fragment. Treatment of the neutral, molybdenum cyclo‐P4 complexes Mo(η4‐P4)I2(CO)(CNArDipp2)2 and Mo(η4‐P4)(CO)2(CNArDipp2)2 with KC8 produces the dianionic, three‐legged piano stool complexes, [Mo(η4‐P4)(CO)(CNArDipp2)2]2? and [Mo(η4‐P4)(CO)2(CNArDipp2)]2?, respectively. Structural, spectroscopic, and computational studies reveal a similarity to the classic η6‐benzene complex (η6‐C6H6)Mo(CO)3 regarding the metal‐center valence state and electronic population of the planar‐cyclic ligand π system. 相似文献
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Samuel Surez‐Pantiga Raquel Hernndez‐Ruiz Cintia Virumbrales María R. Pedrosa Roberto Sanz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(7):2151-2155
The synthesis of aromatic amines is of utmost importance in a wide range of chemical contexts. We report a direct amination of boronic acids with nitro compounds to yield (hetero)aryl amines. The novel combination of a dioxomolybdenum(VI) catalyst and triphenylphosphine as inexpensive reductant has revealed to be decisive to achieve this new C?N coupling. Our methodology has proven to be scalable, air and moisture tolerant, highly chemoselective and engages both aliphatic and aromatic nitro compounds. Moreover, this general and step‐economical synthesis of aromatic secondary amines showcases orthogonality to other aromatic amine syntheses as it tolerates aryl halides and carbonyl compounds. 相似文献
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Margherita Pucino Feng Zhai Christopher P. Gordon Deni Mance Amir H. Hoveyda Richard R. Schrock Christophe Copret 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):11942-11945
Grafting a molybdenum oxo alkylidene on silica (partially dehydroxylated at 700 °C) affords the first example of a well‐defined silica‐supported Mo oxo alkylidene, which is an analogue of the putative active sites in heterogeneous Mo‐based metathesis catalysts. In contrast to its tungsten analogue, which shows poor activity towards terminal olefins because of the formation of a stable off‐cycle metallacyclobutane intermediate, the Mo catalyst shows high metathesis activity for both terminal and internal olefins that is consistent with the lower stability of Mo metallacyclobutane intermediates. This Mo oxo metathesis catalyst also outperforms its corresponding neutral silica‐supported Mo and W imido analogues. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(50):16302-16306
The highly efficient electrochemical hydrogen evolution reaction (HER) provides a promising pathway to resolve energy and environment problems. An electrocatalyst was designed with single Mo atoms (Mo‐SAs) supported on N‐doped carbon having outstanding HER performance. The structure of the catalyst was probed by aberration‐corrected scanning transmission electron microscopy (AC‐STEM) and X‐ray absorption fine structure (XAFS) spectroscopy, indicating the formation of Mo‐SAs anchored with one nitrogen atom and two carbon atoms (Mo1N1C2). Importantly, the Mo1N1C2 catalyst displayed much more excellent activity compared with Mo2C and MoN, and better stability than commercial Pt/C. Density functional theory (DFT) calculation revealed that the unique structure of Mo1N1C2 moiety played a crucial effect to improve the HER performance. This work opens up new opportunities for the preparation and application of highly active and stable Mo‐based HER catalysts. 相似文献
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Tomohiro Agou Tatsuya Wasano Takahiro Sasamori Jing‐Dong Guo Shigeru Nagase Norihiro Tokitoh 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(33):9704-9707
Treatment of 1‐bromo‐2,3,4,5‐tetraethylalumole ( 1 ) with 3‐hexyne afforded the corresponding product 1‐bromo‐1‐alumacyclonona‐2,4,6,8‐tetraene ( 2 ), accompanied by the formation of hexaethylbenzene. In the crystalline state, 2 forms a Br‐bridged dimer with a pseudo C2‐symmetric and twisted AlC8 nine‐membered ring. Deuterium‐labeling experiments and DFT calculations on the reaction of 1 with 3‐hexyne suggested that 1‐bromo‐1‐alumacyclohepta‐2,4,6‐triene, which is formed by the insertion of one molecule of 1‐hexyne into the Al C bond of alumole 1 , is the key intermediate for the generation of 2 as well as hexaethylbenzene. 相似文献
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