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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)...
July 17, 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
Nico Ehrlich, Markus Kreye, Dirk Baabe, Peter Schweyen, Matthias Freytag, Peter G Jones, Marc D Walter
The pyrrolyl-based iron pincer compounds [((tBu)PNP)FeCl] (1), [((tBu)PNP)FeN2] (2), and [((tBu)PNP)Fe(CO)2] (3) were prepared and structurally characterized. In addition, their electronic ground states were probed by various techniques including solid-state magnetic susceptibility and zero-field (57)Fe Mössbauer and X-band electron paramagnetic resonance spectroscopy. While the iron(II) starting material 1 adopts an intermediate-spin (S = 1) state, the iron(I) reduction products 2 and 3 exhibit a low-spin (S = (1)/2) ground state...
July 17, 2017: Inorganic Chemistry
Amanda M Holland, Allen G Oliver, Vlad M Iluc
The structure of a pincer ligand consists of a backbone and two `arms' which typically contain a P or N atom. They are tridentate ligands that coordinate to a metal center in a meridional configuration. A series of three iron complexes containing the pyrrole-based PNP pincer ligand 2,5-bis[(diisopropylphosphanyl)methyl]pyrrolide (PN(pyr)P) has been synthesized. These complexes are possible precursors to new iron catalysts. {2,5-Bis[(diisopropylphosphanyl)methyl]pyrrolido-κ(3)P,N,P'}carbonylchlorido(trimethylphosphane-κP)iron(II), [Fe(C18H34NP2)Cl(C3H9P)(CO)] or [Fe(PN(pyr)P)Cl(PMe3)(CO)], (I), has a slightly distorted octahedral geometry, with the Cl and CO ligands occupying the apical positions...
July 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
Henk Eijer, Tom Hogervorst
Femoroacetabular impingement is the condition whereby parts of the proximal femur mechanically collide with the acetabular rim leading to adjacent and contrecoup acetabular damage. Evidence is growing that at least for cam impingement, and perhaps less so for pincer impingement, there is a relation to the development of osteoarthritis. It has been demonstrated that surgery for impingement can improve function and decrease pain. Intuitively, it would then make sense that surgical intervention would prevent further degeneration...
July 2017: Medical Hypotheses
Kexuan Huang, Jason L Dutton, Caleb D Martin
Boranes are ubiquitous in synthesis and materials but advancements in their development have been primarily restricted to the geometric energetic minima, trigonal planar complexes. This report discloses a class of boranes with expanded bond angles achieved by taking advantage of the structural rigidity of tridentate pincer ligands. The bonding of these novel boranes is investigated by X-ray crystallography and computationally.
July 3, 2017: Chemistry: a European Journal
Nicola C Casartelli, Romana Brunner, Nicola A Maffiuletti, Mario Bizzini, Michael Leunig, Christian W Pfirrmann, Reto Sutter
OBJECTIVES: Aim of this study was to evaluate the flexion-adduction-internal rotation (FADIR) test accuracy for screening cam and pincer morphology in youth male ice hockey players without diagnosed hip disorders. DESIGN: Cross-sectional study. METHODS: Seventy-four ice hockey players with a mean age of 16 years (range: 13-20 years) were assessed unilaterally. The presence of cam and pincer morphology was evaluated using the FADIR test and magnetic resonance imaging (MRI) (reference standard)...
June 21, 2017: Journal of Science and Medicine in Sport
Qiaoling Wei, Feng Zhang, Xiaofang Zhao, Chao Wang, Jianliang Xiao, Weijun Tang
A ruthenium pincer catalyst has been shown to be highly efficient for the hydrogenation of a wide range of α-ketimino esters derived from α-keto esters and chiral 2-methylpropyl-2-sulfinamide, affording chiral aryl glycine derivatives with high yields and diasteroselectivities (20 examples, dr values up to 99 : 1).
July 5, 2017: Organic & Biomolecular Chemistry
Hsin-Hung Kuo, Yi-Ting Chen, Leon R Devereux, Chung-Chih Wu, Mark A Fox, Chu-Yun Kuei, Yun Chi, Gene-Hsiang Lee
Emissive Ir(III) metal complexes possessing two tridentate chelates (bis-tridentate) are known to be more robust compared to those with three bidentate chelates (tris-bidentate). Here, the deep-blue-emitting, bis-tridentate Ir(III) metal phosphors bearing both the dicarbene pincer ancillary such as 2,6-diimidazolylidene benzene and the 6-pyrazolyl-2-phenoxylpyridine chromophoric chelate are synthesized. A deep-blue organic light-emitting diode from one phosphor exhibits Commission Internationale de l'Eclairage (CIE(x,y) ) coordinates of (0...
June 21, 2017: Advanced Materials
M Simon, F Breher
Silyl ligands are of great interest in transition metal coordination chemistry since they exhibit a strong trans-influence and create electron rich metals centres, which are in turn eligible to activate reagents. This review presents and discusses the use of multidentate Si-based ligand systems in transition metal coordination chemistry. These include tri- and tetradentate pincer and scorpionate-type ligands, which have been developed in recent years in order to tailor both steric and electronic properties for achieving a defined control over the reactivity of a transition metal complex...
June 27, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Bent Lund, Bjarne Mygind-Klavsen, Torsten Grønbech Nielsen, Niels Maagaard, Otto Kraemer, Per Hölmich, Søren Winge, Martin Lind
The Danish Hip Arthroscopy Registry (DHAR) was initiated in January 2012 as a web-based prospective registry. The purpose of this study was to evaluate and report the first registry based outcome data of a national population with radiological and clinical femoroacetabular impingement (FAI) undergoing hip arthroscopic treatment. Our primary hypothesis was that patients undergoing hip arthroscopy would improve significantly in pain, quality of life and sports related outcome measurements in Patient Related Outcome Measures (PROM)...
July 2017: Journal of Hip Preservation Surgery
Fernando M Comba, Pablo A Slullitel, Pedro Bronenberg, Gerardo Zanotti, Martin A Buttaro, Francisco Piccaluga
In order to access and resect the acetabular rim, arthroscopic acetabuloplasty was described with labral detachment. When the chondrolabral junction remains intact, acetabuloplasty and labral refixation can be performed maintaining an unharmed labrum. We aimed to evaluate the outcome of a group of patients treated with arthroscopic acetabuloplasty without labral detachment. During the study period, we retrospectively analysed 44 patients with pincer-type o combined impingement and an intact chondroblabral junction, with an average follow-up of 32 months (range: 27-38)...
July 2017: Journal of Hip Preservation Surgery
J W Thomas Byrd, Kay S Jones
Abductor lesions are increasingly recognized as a source of recalcitrant laterally based hip pain and dysfunction. There is a growing body of evidence that many of these may be amenable to endoscopic repair. To report the demographic data and outcomes of endoscopic hip abductor repair. Twelve patients underwent endoscopic abductor repair with 2-year follow-up. These patients were prospectively assessed with modified Harris hip and iHOT scores. The indications for surgery were clinical and MRI findings of symptomatic abductor tears that had failed conservative treatment...
January 2017: Journal of Hip Preservation Surgery
Matthias Mastalir, Ernst Pittenauer, Günter Allmaier, Karl Kirchner
This study represents the first example of a manganese-catalyzed environmentally benign, practical three-component aminomethylation of activated aromatic compounds including naphtols, phenols, pyridines, indoles, carbazoles, and thiophenes in combination with amines and MeOH as a C1 source. These reactions proceed with high atom efficiency via a sequence of dehydrogenation and condensation steps which give rise to selective C-C and C-N bond formations, thereby releasing hydrogen and water. A well-defined hydride Mn(I) PNP pincer complex, recently developed in our laboratory, catalyzes this process in a very efficient way, and a total of 28 different aminomethylated products were synthesized and isolated yields of up to 91%...
June 21, 2017: Journal of the American Chemical Society
Masaru Kondo, Masashi Omori, Tsubasa Hatanaka, Yasuhiro Funahashi, Shuichi Nakamura
The first highly enantioselective reaction of allenylnitriles with imines has been developed. Excellent yields and enantioselectivities were observed for the reaction with various imines using chiral Phebim-Pd(II) complexes. This process offers a simple and efficient synthetic route for various functionalized α-vinylidene-β-aminonitriles and their derivatives.
June 19, 2017: Angewandte Chemie
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