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https://www.readbyqxmd.com/read/28544248/end-functionalized-palladium-scs-pincer-polymers-via-controlled-radical-polymerizations
#1
Diane S Lye, Aaron E Cohen, Madeleine Z Wong, Marcus Weck
A direct and facile route toward semitelechelic polymers, end-functionalized with palladated sulfur-carbon-sulfur pincer (Pd(II) -pincer) complexes is reported that avoids any post-polymerization step. Key to our methodology is the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization with functionalized chain-transfer agents. This strategy yields Pd end-group-functionalized materials with monomodal molar mass dispersities (Đ) of 1.18-1.44. The RAFT polymerization is investigated using a Pd(II) -pincer chain-transfer agent for three classes of monomers: styrene, tert-butyl acrylate, and N-isopropylacrylamide...
May 22, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28544219/mechanism-based-enantiodivergence-in-manganese-reduction-catalysis-a-chiral-pincer-complex-for-the-highly-enantioselective-hydroboration-of-ketones
#2
Lutz Gade, Hubert Wadepohl, Vladislav Vasilenko, Clemens K Blasius
A manganese alkyl complex containing a chiral "boxmi" pincer ligand is a precatalyst for a catalyst of unprecedented activity and selectivity in the enantioselective hydroboration of ketones producing preparatively useful chiral alcohols in excellent yields and up to >99 %ee. It is applicable for both aryl alkyl and dialkyl ketone reduction under mild conditions (TOF >450 h-1 at -40°C) and an earth abundant base metal catalyst which operates at very low catalyst loadings (as low as 0.1 mol%) and with a high level of functional group tolerance...
May 24, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28542878/foot-shape-in-arboreal-birds-two-morphological-patterns-for-the-same-pincer-like-tool
#3
Anick Abourachid, Anne-Claire Fabre, Raphaël Cornette, Elizabeth Höfling
The feet are the only contact between the body and the substrate in limbed animals and as such they provide a crucial interface between the animal and its environment. This is especially true for bipedal and arboreal species living in a complex three-dimensional environment that likely induces strong selection on foot morphology. In birds, foot morphology is highly variable, with different orientations of the toes, making it a good model for the study of the role of functional, developmental, and phylogenetic constraints in the evolution of phenotypic diversity...
May 23, 2017: Journal of Anatomy
https://www.readbyqxmd.com/read/28537598/structural-and-functional-synthetic-model-of-mono-iron-hydrogenase-featuring-an-anthracene-scaffold
#4
Junhyeok Seo, Taylor A Manes, Michael J Rose
Mono-iron hydrogenase was the third type of hydrogenase discovered. Its Lewis acidic iron(II) centre promotes the heterolytic cleavage of the H-H bond and this non-redox H2 activation distinguishes it from the well-studied dinuclear [FeFe] and [NiFe] hydrogenases. Cleavage of the H-H bond is followed by hydride transfer to the enzyme's organic substrate, H4MPT(+), which serves as a CO2 'carrier' in methanogenic pathways. Here we report a scaffold-based synthetic approach by which to model mono-iron hydrogenase using an anthracene framework, which supports a biomimetic fac-C,N,S coordination motif to an iron(II) centre...
June 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28523425/characterization-of-electrocorticogram-high-gamma-signal-in-response-to-varying-upper-extremity-movement-velocity
#5
Po T Wang, Colin M McCrimmon, Christine E King, Susan J Shaw, David E Millett, Hui Gong, Luis A Chui, Charles Y Liu, Zoran Nenadic, An H Do
The mechanism by which the human primary motor cortex (M1) encodes upper extremity movement kinematics is not fully understood. For example, human electrocorticogram (ECoG) signals have been shown to modulate with upper extremity movements; however, this relationship has not been explicitly characterized. To address this issue, we recorded high-density ECoG signals from patients undergoing epilepsy surgery evaluation as they performed elementary upper extremity movements while systematically varying movement speed and duration...
May 18, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28517014/n-atom-transfer-via-thermal-or-photolytic-activation-of-a-co-azido-complex-with-a-pnp-pincer-ligand
#6
V Vreeken, L Baij, B de Bruin, M A Siegler, J I van der Vlugt
Thermal or photolytic activation of well-defined mononuclear [Co(N3)(PNP)] (PNP = 2,2'-bis(diisopropylphosphino)-4,4'-ditolylamido) results in the structurally characterized dinuclear species [Co(μ-N;κ(3)-P,N,N-PN(P)N)]2 (3), with two N-bridging phosphiniminato bridgeheads. Density Functional Theory (DFT) calculations indicate the intermediacy of a mononuclear cobalt-nitrido complex, followed by N-migratory insertion into a Co-P bond. Reaction of 3 with two equiv. HCl leads to rupture of the dimer with formation of mononuclear [CoCl(PN(P)N(H))] (4) by protonation of the N-bridges...
May 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28512691/complete-circumferential-osseous-extension-in-the-acetabular-rim-occurs-regardless-of-acetabular-coverage
#7
Keisuke Watarai, Fumihiko Kimura, Yuho Kadono, Yoon Taek Kim, Mamoru Niitsu, Hiromi Oda, Hirohiko Azuma
BACKGROUND: Complete circumferential osseous extension in the acetabular rim has been reported to occur in the deep hip with pincer impingement. However, this phenomenon occasionally is observed in dysplastic hips without pincer impingement, and the degree to which this finding might or might not be associated with hip pain, and how often it occurs bilaterally among patients, are not well characterized. QUESTIONS/PURPOSES: (1) To determine the proportion of patients with complete circumferential osseous extension in the acetabular rim using three-dimensional (3-D) CT in patients with and without hip pain who had CT scans obtained for various reasons...
May 16, 2017: Clinical Orthopaedics and related Research
https://www.readbyqxmd.com/read/28510799/practical-surgical-techniques-for-lymphadenectomy-along-the-right-recurrent-laryngeal-nerve-during-thoracoscopic-esophagectomy-in-the-prone-position
#8
Taro Oshikiri, Tetsu Nakamura, Yukiko Miura, Hiroshi Hasegawa, Masashi Yamamoto, Shingo Kanaji, Kimihiro Yamashita, Yoshiko Matsuda, Takeru Matsuda, Yasuo Sumi, Satoshi Suzuki, Yoshihiro Kakeji
BACKGROUND: In esophageal squamous cell cancer (SCC), lymphadenectomy along the right recurrent laryngeal nerve (RLN) is important for disease control. The metastatic rate was 33% and the 5-year overall survival rate of these patients was 33.3%,1 but the risk of RLN palsy increases.2 We reported a reliable new method ('Pincers Maneuver')3 for lymphadenectomy along the right RLN during thoracoscopic esophagectomy in the prone position (TEP), and hereby present our video, aimed at providing a complete and safe dissection...
May 16, 2017: Annals of Surgical Oncology
https://www.readbyqxmd.com/read/28507693/fluorocarbene-fluoroolefin-and-fluorocarbyne-complexes-of-rh
#9
Christopher J Pell, Yanjun Zhu, Rafael Huacuja, David E Herbert, Russell P Hughes, Oleg V Ozerov
The manuscript reports the synthesis, characterization, and analysis of electronic structure in a series of complexes of small perfluorocarbon ligands with the (PNP)Rh fragment (where PNP is a diarylamido/bis(phosphine) pincer ligand). Reactions of (PNP)Rh(TBE) as the source of (PNP)Rh with CHF3 and C2HF5 produced perfluoroalkylidene complexes (PNP)Rh 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 CF2 and (PNP)RhC(F)(CF3)...
April 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28492693/nickel-catalyzed-enantioselective-hydroarsination-of-nitrostyrene
#10
Wee Shan Tay, Xiang-Yuan Yang, Yongxin Li, Sumod A Pullarkat, Pak-Hing Leung
A catalytic asymmetric hydroarsination reaction of an activated alkene viz. (E)-nitrostyrene was developed using chiral PCP Pt-, Pd- and Ni-pincer complexes as catalysts. The corresponding chiral tertiary arsine adduct was obtained in ees of up to 80% under mild reaction conditions using the PCP Ni-Cl pincer catalyst. The arsine adduct was furnished with catalyst loadings of 1-5 mol% and the reaction duration ranging from <5 min to 180 min. The subsequent coordination of the hydroarsination product to gold(i) chloride allowed for the confirmation of the stereochemistry of the arsine adduct via crystallographic analysis...
May 11, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28487915/donor-ligands-based-on-tricoordinate-boron-formed-by-b-h-activation-of-bis-phosphine-boronium-salts
#11
Maik Grätz, Andreas Bäcker, Lisa Vondung, Leon Maser, Arian Reincke, Robert Langer
We report a novel method for the preparation of PBP-pincer complexes from bis(phosphine)boronium salts. The central (R3P)2HB-moiety in a palladium complex is demonstrated to be a L-type ligand, therewith completing a series of pincer-type complexes with Z-, X- and L-type boron-based ligands, respectively.
May 10, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28466939/first-examples-of-tri-and-tetraphosphametacyclophanes-synthesis-and-isolation-of-an-unusual-hexapalladium-complex-containing-pincer-units-with-pd-p-covalent-bonds
#12
Vitthalrao S Kashid, Latchupatula Radhakrishna, Maravanji S Balakrishna
The synthesis of the first examples of tri- and tetraphosphametacyclophanes [m-{-C(O)C5H3N(C(O)PPh)}3 (1) and m-{-C(O)C5H3N(C(O)PPh)}4 (2)] is described. The reaction of 1 with [Pd(η(3)-C3H5)Cl]2 yielded a rare hexapalladium(ii) complex with four Pd-P covalent bonds.
May 3, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28452422/cobalt-catalyzed-alkylation-of-secondary-alcohols-with-primary-alcohols-via-borrowing-hydrogen-hydrogen-autotransfer
#13
Rhett Kempe, Frederik Freitag, Torsten Irrgang
Alcohols are promising sustainable starting materials since they can be obtained from abundant and indigestible biomass. The substitution of expensive noble metals in catalysis by earth abundant 3d metals, such as Mn, Fe or Co, (nonprecious or base metals) is a related key concept with respect to sustainability. Herein, we report on the first cobalt catalyzed alkylation of secondary alcohols with primary alcohols. Easy-to-synthesize and easy-to-activate PN5P-pincer ligand stabilized Co complexes developed in our laboratory mediate the reaction most efficiently...
April 28, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28443934/hg-ii-and-pd-ii-complexes-with-a-new-selenoether-bridged-biscarbene-ligand-efficient-mono-and-bis-arylation-of-methyl-acrylate-with-a-pincer-biscarbene-pd-ii-precatalyst
#14
Rishu, Billa Prashanth, Deependra Bawari, Ushnish Mandal, Aditya Verma, Angshuman Roy Choudhury, Sanjay Singh
Two equivalents of 1-benzyl-3-bromoethylbenzimidazolium bromide couple with Na2Se to produce the first selenoether bridged bis-benzimidazolium salt (LH2)Br2. The nitrate (LH2)(NO3)2 and tetrafluoroborate (LH2)(BF4)2 salts were also synthesized from (LH2)Br2. The reaction of Hg(OAc)2 with (LH2)Br2 gave the first pseudo pincer carbene mercury complex, [Hg(L-κ(2)C)][HgBr4] (C1). Different complexes of Pd(ii) with selenoether bridged carbene were obtained using (LH2)Br2 and (LH2)(NO3)2. Syntheses of these complexes were dependent on the counter anion and the temperature...
April 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28441013/cytotoxicity-of-pyrazine-based-cyclometalated-c-n-pz-c-au-iii-carbene-complexes-impact-of-the-nature-of-the-ancillary-ligand-on-the-biological-properties
#15
Benoît Bertrand, Julio Fernandez-Cestau, Jesus Angulo, Marco M D Cominetti, Zoë A E Waller, Mark Searcey, Maria A O'Connell, Manfred Bochmann
The synthesis of a series of cyclometalated gold(III) complexes supported by pyrazine-based (C^N^C)-type pincer ligands is reported, including the crystal structure of a cationic example. The compounds provide a new platform for the study of antiproliferative properties of gold(III) complexes. Seven complexes were tested: the neutral series (C^N(pz)^C)AuX [X = Cl (1), 6-thioguanine (4), C≡CPh (5), SPh (6)] and an ionic series that included the N-methyl complex [(C^N(pzMe)^C)AuCl]BF4 (7) and the N-heterocyclic carbene complexes [(C^N(pz)^C)AuL](+) with L = 1,3-dimethylbenzimidazol-2-ylidene (2) or 1,3,7,9-tetramethylxanthin-8-ylidene (3)...
May 15, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28436068/dinitrogen-splitting-coupled-to-protonation
#16
Gleb A Silantyev, Moritz Förster, Bastian Schluschaß, Josh Abbenseth, Christian Würtele, Christian Volkmann, Max C Holthausen, Sven Schneider
The coupling of electron- and proton-transfer steps provides a general concept to control the driving force of redox reactions. N2 splitting of a molybdenum dinitrogen complex into nitrides coupled to a reaction with Brønsted acid is reported. Remarkably, our spectroscopic, kinetic, and computational mechanistic analysis attributes N-N bond cleavage to protonation in the periphery of an amide pincer ligands rather than the {Mo-N2 -Mo} core. The strong effect on electronic structure and ultimately the thermochemistry and kinetic barrier of N-N bond cleavage is an unusual case of a proton-coupled metal-to-ligand charge transfer process, highlighting the use of proton-responsive ligands for nitrogen fixation...
April 24, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28429449/non-pincer-type-manganese-complexes-as-efficient-catalysts-for-the-hydrogenation-of-esters
#17
Robbert van Putten, Evgeny A Uslamin, Marcel Garbe, Chong Liu, Angela Gonzalez-de-Castro, Martin Lutz, Kathrin Junge, Emiel J M Hensen, Matthias Beller, Laurent Lefort, Evgeny A Pidko
Catalytic hydrogenation of carboxylic acid esters is essential for the green production of pharmaceuticals, fragrances, and fine chemicals. Herein, we report the efficient hydrogenation of esters with manganese catalysts based on simple bidentate aminophosphine ligands. Monoligated Mn PN complexes are particularly active for the conversion of esters into the corresponding alcohols at Mn concentrations as low as 0.2 mol % in the presence of sub-stoichiometric amounts of KO(t) Bu base.
April 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28420048/pincer-nail-in-a-lupus-patient
#18
T H V Azevedo, C L S Neiva, R V Consoli, A C D Couto, A F M P Dias, E J R Souza
Pincer nail is a transverse overcurvature of the nail plate that may appear in association with a variable number of diseases. We present a case report of a 28-year-old woman with pincer nail deformity associated with systemic lupus erythematosus. A renal biopsy confirmed class V lupus nephritis and treatment had included systemic steroids and cyclophosphamide. After 6 months there was a marked improvement of nail deformities.
January 1, 2017: Lupus
https://www.readbyqxmd.com/read/28418439/non-symmetrical-potentially-redox-non-innocent-imino-nhc-pyridine-pincers-via-a-zinc-ion-template-assisted-synthesis
#19
Thomas Simler, Andreas A Danopoulos, Pierre Braunstein
New non-symmetrical, redox-active imino NHC pyridine pincer ligands, 2-(R(1)-imidazol-2-ylidene)-6-(R(2)N[double bond, length as m-dash]CH)-pyridine (R(1) = 2,6-diisopropylphenyl (DiPP), R(2) = 2,4,6-trimethylphenyl (Mes), 4B; R(1) = R(2) = DiPP, 4C), have been accessed by a Zn(II)-promoted modular synthesis involving the quaternization of R(1)-imidazole by [Zn(κN(imine)κN(pyridine))(2-(R(2)N[double bond, length as m-dash]CH)-6-bromo-pyridine)Cl2], followed by Zn(II) removal and deprotonation of imidazolium pro-ligands...
May 9, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28406030/three-different-reactions-one-catalyst-a-cu-i-pnp-pincer-complex-as-catalyst-for-c-c-and-c-n-cross-couplings
#20
Matthias Mastalir, Ernst Pittenauer, Berthold Stöger, Günter Allmaier, Karl Kirchner
An air-stable, thermally robust, and well-defined Cu(I) PNP pincer complex based on the 2,6-diaminopyridine scaffold is described. This complex is an active catalyst for the cross-couplings of a range of aryl and heteroaryl (including benzoxazole, thiazole, pyridine, and thiophene) halides with different organomagnesium reagents, alkynes, and aryl-amines giving excellent to good isolated yields.
April 13, 2017: Organic Letters
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