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Muniyappan Rajiv Gandhi, Manabu Yamada, Kazutoshi Haga, Atsushi Shibayama
SCS pincer ligands 1-4 were synthesised, and their ability to extract Pd(II) from HCl and HNO3 media was studied. The Pd(II) extraction properties of 1-4 were compared with those of commercial extractants (DOS and LIX(®)84-I) in kerosene. 1 and 2 showed superior Pd(II) extractability (E% = 99.9) relative to DOS and LIX(®)84-I from 0.1-8.0 M HCl and to DOS from 0.1-8.0 M HNO3 and mixed HCl + HNO3 media. The Pd(II) extraction rate, acid durability, the most suitable organic/aqueous (O/A) phase ratio, and Pd(II) loading capacity of extractants 1, 2, and DOS were evaluated...
August 18, 2017: Scientific Reports
Shaomin Fu, Zhihui Shao, Yujie Wang, Qiang Liu
Biomass-derived ethanol is an important renewable feedstock. Its conversion into high-quality biofuels is a promising route to replace fossil resources. Herein, an efficient manganese-catalyzed Guerbet-type condensation reaction of ethanol to form 1-butanol was explored. This is the first example of upgrading ethanol into higher alcohols using a homogeneous non-noble-metal catalyst. This process proceeded selectively in the presence of a well-defined manganese pincer complex at the parts per million (ppm) level...
August 18, 2017: Journal of the American Chemical Society
Naomi Steiner, Alcy Torres, Arathi Reddy, Marilyn Augustyn
David is a 22-month-old boy who is new to your practice. He recently moved from a rural area in the Midwest. His father is in the United States Air Force, and his mother works as a full-time homemaker. Their household includes 5 older siblings. The family moves every year because of the father's Air Force placement.David was born full-term in Virginia, with no reported pregnancy complications and no alcohol, tobacco, or drug exposure. He was delivered vaginally, with Apgar scores of 7 and 9, respectively and no respiratory issues...
August 9, 2017: Journal of Developmental and Behavioral Pediatrics: JDBP
Noel Angel Espinosa-Jalapa, Amit Kumar, Gregory Leitus, Yael Diskin-Posner, David Milstein
The first example of base-metal-catalyzed dehydrogenative coupling of diols and amines to form cyclic imides is reported. The reaction is catalyzed by a pincer complex of the earth abundant manganese and forms hydrogen gas as the sole byproduct, making the overall process atom economical and environmentally benign.
August 16, 2017: Journal of the American Chemical Society
John P Salvo, Jake Zarah, Zaira S Chaudhry, Kirsten L Poehling-Monaghan
BACKGROUND: The frequency of hip arthroscopy for the treatment of acute and chronic chondrolabral pathology and femoroacetabular impingement (FAI) has increased exponentially over the past decade. While surgeon and patient radiation exposure has been well documented in other areas of the orthopaedic literature, little is known about the procedure-specific and cumulative doses affecting the hip arthroscopist. PURPOSE: To determine the mean annual radiation exposure to the hip arthroscopist and the mean surgeon exposure per case...
July 2017: Orthopaedic Journal of Sports Medicine
Subrata Chakraborty, Uttam Kumar Das, Yehoshoa Ben-David, David Milstein
Catalytic α-olefination of nitriles using primary alcohols, via dehydrogenative coupling of alcohols with nitriles, is presented. The reaction is catalyzed by a pincer complex of an earth-abundant metal (manganese), in the absence of any additives, base, or hydrogen acceptor, liberating dihydrogen and water as the only byproducts.
August 16, 2017: Journal of the American Chemical Society
James D Cope, Nalaka P Liyanage, Paul J Kelley, Jason A Denny, Edward J Valente, Charles Edwin Webster, Jared H Delcamp, T Keith Hollis
A CCC-NHC pincer Ni(ii)Cl complex was prepared according to the metallation/transmetallation methodology. It was fully characterized by electrochemical, NMR spectroscopic, theoretical, and X-ray crystallographic methods. The complex and its cation were evaluated for electrocatalytic reduction of CO2 under a variety of conditions and found to provide some of the fastest catalytic rates and highest substrate selectivities (CO2vs. H(+)) reported. Rates improved in the presence of water and, significantly, catalysis occurred at the first reduction potential, presumably at the Ni(i) state...
August 9, 2017: Chemical Communications: Chem Comm
Kazunari Nakajima, Takeru Kato, Yoshiaki Nishibayashi
To utilize iron complexes as catalysts, the application of a well-designed ligand is critical to control the reactivity of the iron center. Recently, our group has succeeded in the synthesis of iron complexes bearing a pyrrolide-based PNP pincer ligand and their application to the catalytic transformation of dinitrogen into ammonia under mild reaction conditions. As an extensive study, we report the iron-catalyzed hydroboration of alkynes with pinacolborane, where the corresponding E-isomers are obtained selectively...
August 7, 2017: Organic Letters
Svetlana G Churusova, Diana V Aleksanyan, Ekaterina Yu Rybalkina, Olga Yu Susova, Valentina V Brunova, Rinat R Aysin, Yulia V Nelyubina, Alexander S Peregudov, Evgenii I Gutsul, Zinaida S Klemenkova, Vladimir A Kozlov
The reactions of picolinyl and 4-chloropicolinyl chlorides with methyl esters of S-methyl-l-cysteine, l- and d-methionine, and l-histidine afforded a series of functionalized carboxamides, which readily formed pincer-type complexes upon interaction with PdCl2(NCPh)2 in solution under mild conditions. The direct cyclopalladation of the ligands derived was also accomplished in the solid phase, in particular, mechanochemically, although it was complicated by the partial deactivation of the starting amides. The resulting complexes with 5,5- and 5,6-membered fused metallocycles were fully characterized by IR and NMR spectroscopy, including variable-temperature and 2D-NMR studies...
August 3, 2017: Inorganic Chemistry
Alexander V Polezhaev, Chun-Hsing Chen, Adam S Kinne, Alyssa C Cabelof, Richard L Lord, Kenneth G Caulton
The synthesis of bis(N1-phenyl-5-hydroxypyrazol-3-yl)pyridines ("L") is described, and these are silylated to achieve analogues ("Si2L") without the variable of the hydroxyl proton mobility. One hydroxyl example is characterized in its bis-pincer iron(II) complex, which shows every OH proton involved in hydrogen bonding. The steric bulk of the silylated N-phenyl-substituted ligands allows the synthesis and characterization of paramagnetic (Si2L)FeCl2 complexes, and one of these is reduced, under CO, to give the diamagnetic (Si2L)Fe(CO)2 species...
August 1, 2017: Inorganic Chemistry
Marcus P Wenzl, Markus Heller, Viktor Janz, Carsten Perka, Georgi I Wassilew
BACKGROUND: Plain radiography, 2-dimensional (2D) magnetic resonance imaging (MRI), and computed tomography (CT) do not precisely display morphology and acetabular coverage in developmental dysplasia of the hip or pincer-type femoroacetabular impingement. Pelvic position and pelvic tilt affect assessment of the acetabular parameters, leading to misinterpretation. OBJECTIVE: We tested a 3-dimensional (3D) CT evaluation script to calculate the crossover sign (COS), acetabular coverage and morphology...
July 21, 2017: Technology and Health Care: Official Journal of the European Society for Engineering and Medicine
Xiaoyu Ren, Christophe Gourlaouen, Marcel Wesolek, Pierre Braunstein
The imidazolium chloride [C3H3N(C3H6NMe2)N{C(Me)(=NDipp)}]Cl (Dipp = 2,6-diisopropyl phenyl) (1), potential precursor to a tritopic NimineCNHCNamine pincer-type ligand, reacted with [Ni(cod)2] to give a Ni(I)-Ni(I) complex 2 with a rare cod-derived 3-allyl-type bridging ligand. The implied intermediate formation of a Ni-hydride from oxidative-addition of the imidazolium C-H bond did not occur with the symmetrical imidazolium chloride [C3H3N2{C(Me)(=NDipp)}2]Cl (3). Instead, a Ni-Csp3 bond was formed, leading to the neutral NimineCHNimine pincer-type complex Ni[C3H3N2{C(Me)(=NDipp)}2]Cl (4)...
July 31, 2017: Angewandte Chemie
Huaquan Fang, Wenjun Hou, Guixia Liu, Zheng Huang
Incorporating the silicon element into bioactive organic molecules has received increasing attention in medicinal chemistry. Moreover, organosilanes are valuable synthetic intermediates for fine chemicals and materials. Transition metal-catalyzed C-H silylation has become an important strategy for C-Si bond formations. However, despite the great advances in aromatic C(sp(2))-H bond silylations, catalytic methods for aliphatic C(sp(3))-H bond silylations are relatively rare. Here we report a pincer ruthenium catalyst for intramolecular silylations of various primary C(sp(3))-H bonds adjacent to heteroatoms (O, N, Si, Ge), including the first intramolecular silylations of C-H bonds α to O, N, and Ge...
August 10, 2017: Journal of the American Chemical Society
Dmitry A Valyaev, Jérémy Willot, Loïc P Mangin, Davit Zargarian, Noël Lugan
The alkylation of N-(2-pyridyl)imidazole by the Mn(I) methylene-phosphonium complex [Cp(CO)2Mn(η(2)-P,C-Ph2P[double bond, length as m-dash]C(H)Ph)]BF4 offers a straightforward route to a tridentate pro-ligand featuring an NHC core and phosphine/pyridine arms. The ability of this PĈN ligand to coordinate in a pincer mode was recognized in Rh(I), Rh(III), and Ni(II) complexes.
July 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Mireia Rovira, Lucie Jašíková, Erik Andris, Ferran Acuña-Parés, Marta Soler, Imma Güell, Ming-Zheng Wang, Laura Gómez, Josep M Luis, Jana Roithová, Xavi Ribas
Unraveling the mechanistic details of copper-catalyzed arylation of nucleophiles (Ullmann-type couplings) is a very challenging task. It is a matter of intense debate whether it is a radical-based process or an organometallic redox-based process. The ancillary ligand choice in Ullmann-type couplings plays a key role in such transformations and can strongly influence the catalytic efficiency as well as the mechanism. Here, we show how a predesigned tridentate pincer-like catalyst undergoes a deactivation pathway through a Cu(I)/Cu(III) prototypical mechanism as demonstrated by helium-tagging infrared photodissociation (IRPD) spectroscopy and DFT studies, lending a strong support to the existence of an aryl-Cu(III) species in the Ullmann couplings using this tridentate ligand...
July 21, 2017: Chemical Communications: Chem Comm
Marcel Garbe, Kathrin Junge, Svenja Walker, Zhihong Wei, Haijun Jiao, Anke Spannenberg, Stephan Bachmann, Michelangelo Scalone, Matthias Beller
A new chiral manganese PNP pincer complex is described. Asymmetric hydrogenation of several prochiral ketones with molecular hydrogen in the presence of this complex proceeds under mild conditions (40 °C, 4 h, 30 bar H₂). Besides high catalytic activity for aromatic substrates, aliphatic ketones are hydrogenated with remarkable selectivities (er up to 92:8). DFT calculations support an outer sphere hydrogenation mechanism as well as the experimentally determined stereochemistry.
July 21, 2017: Angewandte Chemie
Jiashen Qiu, Di Wu, Pran Gopal Karmaker, Guirong Qi, Peng Chen, Hongquan Yin, Fu-Xue Chen
The first example of catalytic asymmetric electrophilic cyanation of 3-substituted oxindoles has been achieved using readily accessible 4-acetylphenyl cyanate as the cyano source. Thus, a series of all-carbon quaternary center 3-aryl-3-cyano oxindoles were prepared using a zinc complex of a chiral pincer ligand as the catalyst in high yields (up to 95%) and excellent enantioselectivities (up to >99% ee) in the presence of 4 Å MS and 2,6-lutidine in THF at 0 °C.
July 20, 2017: Organic Letters
Zhu-Lin Xie, Gummadi Durgaprasad, Azim K Ali, Michael J Rose
A C,N,S pincer complex has been synthesized for structural modeling of the organometallic active site of mono-[Fe] hydrogenase (HMD). The C,N,S chelate allows for systematic investigation of the substitution reactions of CO and other exogenous X/L-type ligands, as well as examination of the exact roles of the Fe-carbamoyl and {Fe(CO)2}(2+) units in stabilizing the low-spin Fe(ii) center. Reaction of the 'apo-ligand' 6-(2-(methylthio)phenyl)pyridin-2-amine ((H2N)N(py)S(Me)) with [Fe(CO)4(Br)2] affords the organometallic complex [((O[double bond, length as m-dash])C(NH)N(py)S(Me))Fe(CO)2(Br)] (1)...
August 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Laura E Diamond, Kim L Bennell, Tim V Wrigley, Rana S Hinman, John Oʼdonnell, Paul W Hodges
PURPOSE: Identification of the biomechanical alterations in individuals with symptomatic femoroacetabular impingement (FAI) is critical to understand the pathology and inform treatments. Yet hip function in this condition is poorly defined. Squatting requires large hip flexion range and involves motion toward the position of hip impingement; thus, it is likely to expose modified biomechanics in these individuals. This study aimed to determine whether hip and pelvis biomechanics differ between individuals with and without symptomatic FAI during an unconstrained deep squat and a constrained squat designed to limit compensation by the pelvis and trunk...
August 2017: Medicine and Science in Sports and Exercise
Alejandro Espejo-Baena, Alejandro Espejo-Reina, María Josefa Espejo-Reina, María Belén Martín-Castilla, Jaime Dalla-Rosa Nogales, Enrique Sevillano-Pérez
A technique for posterior meniscal root reinsertion is presented. With the arthroscope in the central transtendinous portal for a better view, a 5-mm transtibial tunnel is created with the aid of an anterior cruciate ligament guide open to 45°. A suture device, which consists of a long needle with an eyelet on its tip, is introduced through the tunnel with a suture thread inserted through the eyelet, while the meniscus is stabilized with a grasper inserted through the anterior portal. The meniscus is pierced with the device, and the suture thread is recovered with said grasper...
June 2017: Arthroscopy Techniques
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