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Elisabetta Alberico, Alastair J J Lennox, Lydia K Vogt, Haijun Jiao, Wolfgang Baumann, Hans-Joachim Drexler, Martin Nielsen, Anke Spannenberg, Marek P Checinski, Henrik Junge, Matthias Beller
Ruthenium PNP complex 1a (RuH(CO)Cl(HN(C2H4Pi-Pr2)2)) represents a state-of-the-art catalyst for low-temperature (<100 °C) aqueous methanol dehydrogenation to H2 and CO2. Herein, we describe an investigation that combines experiment, spectroscopy and theory to provide a mechanistic rationale for this process. During catalysis, the presence of two anionic resting states was revealed, Ru-dihydride (3-) and Ru-monohydride (4-) that are deprotonated at nitrogen in the pincer ligand backbone. DFT calculations showed that O- and CH- coordination modes of methoxide to ruthenium compete, and form complexes 4- and 3-, respectively...
October 19, 2016: Journal of the American Chemical Society
Huaquan Fang, Le Guo, Yuxuan Zhang, Wubing Yao, Zheng Huang
A pincer Ru(II) catalyst for the highly efficient undirected silylation of O- and S-heteroarenes with (TMSO)2MeSiH and Et3SiH is described, producing heteroarylsilanes with exclusive C2-regioselectivity, good functional-group tolerance, and high turnover numbers (up to 1960). The synthetic utility of the silylated products is demonstrated by Pd-catalyzed Hiyama-Denmark cross-coupling under mild conditions. One-pot, two-step silylation and coupling procedures have been also developed.
October 18, 2016: Organic Letters
Lisa Vondung, Nicolas Frank, Maximilian Fritz, Lukas Alig, Robert Langer
Stabilized borylenes (L2 BH:) with weakly π-accepting substituents L, such as phosphines, were previously believed to be unstable. In the current manuscript, we describe a series of complexes formally containing a phosphine-stabilized borylene or boryl anion. In contrast to common trivalent boron compounds, the boron-based ligands in this study act as electron-donating ligands. The reported iron hydride complexes exhibit a unique reactivity pattern, undergoing a reversible B-H reductive elimination concomitant with oxidation of the boron(I) center...
October 14, 2016: Angewandte Chemie
Go Hamasaka, Tsubasa Muto, Yoshimichi Andoh, Kazushi Fujimoto, Kenich Kato, Masaki Tanaka, Susumu Okazaki, Yasuhiro Uozumi
Wide-angle X-ray scattering experiments and all-atomistic molecular dynamics calculations were performed to elucidate the detailed structure of bilayer vesicles constructed by self-assembly of an amphiphilic palladium NCN-pincer complex. We found an excellent agreement between the experimental and calculated X-ray spectra and between the membrane thickness determined from a TEM image and that calculated from an electron-density profile, indicating that the calculated structure was highly reliable. The analysis of the simulated bilayer structure showed that the membrane was softer than other phospholipid bilayer membranes in general...
October 13, 2016: Chemistry: a European Journal
Sven Schneider, Felix Schneck, Markus Finger, Moniek Tromp
The synthesis of the divinylamido PNP nickel(II) complex [NiBr{N(CHCHPtBu2)2}] is reported. This compound exhibits reversible, ligand centered oxidation and protonation reactions. The resulting pincer chemical non-innocence can be utilized for benzylic C-H hydrogen atom abstraction. The thermochemistry and kinetics of hydrogen atom transfer were examined.
October 13, 2016: Chemistry: a European Journal
Prosenjit Daw, Subrata Chakraborty, Jai Anand Garg, Yehoshoa Ben-David, David Milstein
Herein, the first example of base-metal-catalyzed dehydrogenative coupling of diols and amines to selectively form functionalized 1,2,5-substituted pyrroles liberating water and hydrogen gas as the sole by-products is presented. The reaction is catalyzed by pincer complexes of earth-abundant cobalt.
October 12, 2016: Angewandte Chemie
Mathias Glatz, Christian Schröder-Holzhacker, Bernhard Bichler, Berthold Stöger, Kurt Mereiter, Luis F Veiros, Karl Kirchner
ABSTRACT: In the present work, we have prepared a series of octahedral Fe(II) complexes of the type trans-[Fe(PNP)(CO)2Cl](+)-PNP are tridentate pincer-type ligands based on 2,6-diaminopyridine. These complexes are formed irrespective of the size of the substituents at the phosphorus sites and whether cis-[Fe(PNP)(Cl2)(CO)] or trans-[Fe(PNP)(Cl2)(CO)] are reacted with CO in the presence of 1 equiv of silver salts. X-ray structures of representative complexes are presented. Based on simple bonding considerations the selective formation of trans-dicarbonyl Fe(II) complexes is unexpected...
2016: Monatshefte Für Chemie
Linda E Eijsink, Sébastien C P Perdriau, Johannes G de Vries, Edwin Otten
The pincer complex (PNN)RuH(CO), with a de-aromatized pyridine in the ligand backbone, is shown to react with nitriles in a metal-ligand cooperative manner. This leads to the formation of a series of complexes with new Ru-N(nitrile) and C(ligand)-C(nitrile) bonds. The initial nitrile cycloaddition products, the ketimido complexes 3, have a Brønsted basic (nitrile-derived) Ru-N fragment. This is able to deprotonate a CH2 side-arm of the pincer ligand to give ketimine complexes (4) with a de-aromatized pyridine backbone...
October 12, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Megan K Mills, Colin D Strickland, Mary K Jesse, Peter A Lowry, Omer Mei-Dan, Jonathan A Flug
Osteoarthritis of the hip remains a prevalent disease condition that influences ever-changing treatment options. Procedures performed to correct anatomic variations, and, in turn, prevent or slow the progression of osteoarthritis, are aptly referred to as types of hip preservation surgery (HPS). Conditions that predispose individuals to femoroacetabular impingement (FAI), including pincer- and cam-type morphology, and hip dysplasia are specifically targeted in HPS. Common surgical interventions include acetabuloplasty, osteochondroplasty, periacetabular osteotomy (PAO), and derotational femoral osteotomy (DFO)...
October 2016: Radiographics: a Review Publication of the Radiological Society of North America, Inc
Marin Stančić, Ivana Stančić, Petra Barl, Ivan Pašalić
OBJECTIVE: Scarcity of implants during the economic crisis has partially replaced cervical spondylotic myelopathy decompression and instrumented fusion with implant-less expansile cervical laminopalsty. The aim of the study was comparison of the results obtained with instrumented anterior cervical corpectomy and fusion (ACCF) with implant-less expansile cervical laminoplasty (ECL). METHODS: Patients suffering from cervical spondylotic myelopathy (CSM) Nurick 3-5, with preoperative tethering and postoperative untethering were included...
October 7, 2016: World Neurosurgery
Danny Schuhknecht, Florian Ritter, Michael E Tauchert
The palladium diphosphinoboryl pincer [{(o-PPh2C6H4)2B}Pd(II)I] 8 was prepared from the diphosphinoborane complex 6a. The boryl functionality of the pincer displayed ambiphilic properties allowing: (1) coordination of Lewis basic pyridines to the boryl site and (2) access to palladium diphosphinoborane complex derivatives.
September 27, 2016: Chemical Communications: Chem Comm
Benhua Xu, Xiaoliang Tang, Ji'an Zhou, Wanmin Chen, Haile Liu, Zhenghua Ju, Weisheng Liu
A functional amide-type pincer ligand was designed and synthesized, which could effectively capture Tb(3+) ions to form a phosphorescence complex-based chemosensor Tb-1. The chemosensor could further coordinate with Pb(2+) ions and display a turn-on phosphorescence response. This sensing process was analyzed in detail by steady-state luminescence spectroscopy, time-resolved luminescence spectroscopy, electron microscopy and dynamic light scattering, which suggest that the formation of Pb(2+)-induced hydroxide nanoclusters can adjust the optical signal of the external luminescence compound by embedment and fixation of Tb(3+) complexes...
September 16, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Milan M Milutinović, Jovana V Bogojeski, Olivera Klisurić, Andreas Scheurer, Sofi K C Elmroth, Živadin D Bugarčić
A novel rhodium(iii) complex [Rh(III)(H2L(tBu))Cl3] (1) (H2L(tBu) = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine) containing a pincer type, tridentate nitrogen-donor chelate system was synthesized. Single crystal X-ray structure analysis revealed that 1 crystallizes in the orthorhombic space group Pbcn with a = 20.7982(6), b = 10.8952(4), c = 10.9832(4) Å, V = 2488.80(15) Å(3), and eight molecules in the unit cell. The rhodium center in the complex [Rh(III)(H2L(tBu))Cl3] (1) is coordinated in a slightly distorted octahedral geometry by the tridentate N,N,N-donor and three chloro ligands, adopting a mer arrangement with an essentially planar ligand skeleton...
October 4, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Práxedes Sánchez, Martín Hernández-Juárez, Eleuterio Álvarez, Margarita Paneque, Nuria Rendón, Andrés Suárez
Coordination studies of new lutidine-derived hybrid NHC/phosphine ligands (CNP) to Pd and Ir have been performed. Treatment of the square-planar [Pd(CNP)Cl](AgCl2) complex 2a with KHMDS produces the selective deprotonation at the CH2P arm of the pincer to yield the pyridine-dearomatised complex 3a. A series of cationic [Ir(CNP)(cod)](+) complexes 4 has been prepared by reaction of the imidazolium salts 1 with Ir(acac)(cod). These derivatives exhibit in the solid state, and in solution, a distorted trigonal bipyramidal structure in which the CNP ligands adopt an unusual C(axial)-N(equatorial)-P(equatorial) coordination mode...
October 4, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Tomohiro Mimura, Kanji Mori, Shin Itakura, Yuki Furuya, Taku Kawasaki, Shinji Imai
BACKGROUND: Femoroacetabular impingement (FAI) is thought to be associated with hip osteoarthritis. We investigated the prevalences of radiologic deformities of the pincer, cam, and their combinations in Japanese hip joints using computed tomography (CT) according to the Japanese Hip Society diagnostic guideline for FAI. METHODS: Multi-slice CT images were evaluated. Pincer deformities were defined as: type 1: center-edge angle (CE) ≥40°; type 2: CE ≥ 30° and acetabular roof obliquity ≤0°; type 3: CE ≥ 25° and retroverted acetabulum...
October 6, 2016: Journal of Orthopaedic Science: Official Journal of the Japanese Orthopaedic Association
Toyotaka Nakae, Masakazu Hirotsu, Shigetoshi Aono, Hiroshi Nakajima
Iron(iii) carbonyl complexes are stabilized by a pincer ligand containing pyridine-N, phenyl-C and thiolate-S donors and two axial phosphine ligands. The N,C,S-pincer iron(iii) carbonyl complexes show CO-releasing properties induced by visible light.
October 18, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Sophie De-Botton, Ronit Romm, Guillaume Bensoussan, Maria Hitrik, Sanaa Musa, Dmitri Gelman
The manuscript describes the synthesis and coordination chemistry of a novel diphosphine pincer ligand based on a p-hydroquinone-functionalized dibenzobarrelene scaffold. The p-hydroquinone fragment of the ligand is oxidatively and coordinatively non-innocent and may render new reactivity to the metal center due to implied reversible redox behavior, tautomeric interconversion and metal-hydroxyl/alkoxide coordination switch of the pendant hydroxyl side-arm. Palladium, platinum and iridium complexes were prepared and characterized...
October 12, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Remya Narayanan, Meaghan McKinnon, Blake R Reed, Ken T Ngo, Stanislav Groysman, Jonathan Rochford
The electrochemical properties of two Ni(NNN)X2 pincer complexes are reported where X = Cl or Br and NNN is N,N'-(2,6-diisopropylphenyl)bis-aldiminopyridine. Cyclic voltammetry under 1 atm of CO2 suggests electrocatalytic CO2 reduction activity, however, bulk electrolysis shows a poor Faradaic efficiency for CO evolution with a high Faradaic yield for H2 evolution.
October 4, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Chee Koon Ng, Jie Wu, T S Andy Hor, He-Kuan Luo
Binary catalyst systems comprising a cationic Ru-CNC pincer complex and an alkali metal salt were developed for selective hydroboration of CO2 utilizing pinacolborane at r.t. and 1 atm CO2, with the combination of [Ru(CNCBn)(CO)2(H)][PF6] and KOCO2(t)Bu producing formoxyborane in 76% yield. A bicyclic catalytic mechanism was proposed and discussed.
September 27, 2016: Chemical Communications: Chem Comm
Saravanakumar Elangovan, Jacob Neumann, Jean-Baptiste Sortais, Kathrin Junge, Christophe Darcel, Matthias Beller
Borrowing hydrogen (or hydrogen autotransfer) reactions represent straightforward and sustainable C-N bond-forming processes. In general, precious metal-based catalysts are employed for this effective transformation. In recent years, the use of earth abundant and cheap non-noble metal catalysts for this process attracted considerable attention in the scientific community. Here we show that the selective N-alkylation of amines with alcohols can be catalysed by defined PNP manganese pincer complexes. A variety of substituted anilines are monoalkylated with different (hetero)aromatic and aliphatic alcohols even in the presence of other sensitive reducible functional groups...
October 6, 2016: Nature Communications
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