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Phosphine boran

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https://www.readbyqxmd.com/read/27809358/understanding-the-role-of-dispersion-in-frustrated-lewis-pairs-and-classical-lewis-adducts-a-domain-based-local-pair-natural-orbital-coupled-cluster-study
#1
Giovanni Bistoni, Alexander A Auer, Frank Neese
The interaction of Lewis acids and bases in both classical Lewis adducts and Frustrated Lewis Pairs (FLPs) is investigated in order to elucidate the role that London dispersion plays in the different situations. Our analysis comprises 14 different adducts between the tris(pentafluorophenyl)borane and a series of phosphines, carbenes and amines with various substituents, differing in both steric and electronic properties. The domain based local pair natural orbital coupled-cluster (DLPNO-CCSD(T)) method is used in conjunction with the recently introduced Local Energy Decomposition (LED) analysis in order to obtain state of the art dissociation energies and at the same time a clear-cut definition of the London dispersion component of the interaction, with the ultimate goal to aid in the development of designing principles for acid/base pairs with well-defined bonding features and reactivity...
November 3, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27730749/generation-of-dicoordinate-boron-i-units-by-fragmentation-of-a-tetra-boron-i-molecular-square
#2
Merle Arrowsmith, Dominic Auerhammer, Rüdiger Bertermann, Holger Braunschweig, Gerhard Bringmann, Mehmet Ali Celik, Rian D Dewhurst, Maik Finze, Matthias Grüne, Michael Hailmann, Thomas Hertle, Ivo Krummenacher
Reduction of carbene-borane adduct [(cAAC)BBr2 (CN)] (cAAC=1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) cleanly yielded the tetra(cyanoborylene) species [(cAAC)B(CN)]4 presenting a 12-membered (BCN)4 ring. The analysis of the Kohn-Sham molecular orbitals showed significant borylene character of the B(I) atoms. [(cAAC)B(CN)]4 was found to reduce two equivalents of AgCN per boron center to yield [(cAAC)B(CN)3 ] and fragmented into two-coordinate boron(I) units upon reaction with IMeMe (1,3,4,5-tetramethylimidazol-2-ylidene) to yield the corresponding tricoordinate mixed cAAC-NHC cyanoborylene...
October 12, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27718077/a-theoretical-analysis-of-substituent-electronic-effects-on-phosphine-borane-bonds
#3
Paul A Sibbald
Phosphine-borane adducts are a well-known moiety in synthetic and coordination chemistry. These complexes form a dative bond in which the Lewis basic phosphorus atom donates electron density into an empty p-orbital of the Lewis acidic boron atom. However, donation of the phosphorus lone pair is not the only stabilizing interaction, as hyperconjugation and electrostatic interaction also play important roles in bonding. This paper describes a detailed density functional theory level (B3LYP) study completed to determine the impact electron-donating and withdrawing substituents have on phosphine-borane bonds through the investigation of a series of para-substituted PAr3-BH3 and PH3-BAr3 phosphine-borane adducts...
November 2016: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/27560776/a-triad-of-highly-reduced-linear-iron-nitrosyl-complexes-feno-8-10
#4
Matthew J Chalkley, Jonas C Peters
Given the importance of Fe-NO complexes in both human biology and the global nitrogen cycle, there has been interest in understanding their diverse electronic structures. Herein a redox series of isolable iron nitrosyl complexes stabilized by a tris(phosphine)borane (TPB) ligand is described. These structurally characterized iron nitrosyl complexes reside in the following highly reduced Enemark-Feltham numbers: {FeNO}(8) , {FeNO}(9) , and {FeNO}(10) . These {FeNO}(8-10) compounds are each low-spin, and feature linear yet strongly activated nitric oxide ligands...
September 19, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27524808/searching-for-practically-useful-p-chirogenic-phosphine-ligands
#5
Tsuneo Imamoto
In this account, the design, synthesis, and application of P-chirogenic phosphine ligands that have been mainly carried out in our laboratory over the last three decades are described. Various enantiopure P-chirogenic phosphine ligands have been efficiently prepared by using phosphine boranes as intermediates. Conformationally rigid and electron-rich P-chirogenic phosphine ligands possessing C2 symmetry as well as a bulky alkyl group and a small group at the phosphorus atoms exhibit excellent enantioselectivities and catalytic efficiency in a variety of transition-metal-catalyzed asymmetric reactions...
August 15, 2016: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
https://www.readbyqxmd.com/read/27518583/hydrophosphination-of-bicyclo-1-1-0-butane-1-carbonitriles
#6
John A Milligan, Carl A Busacca, Chris H Senanayake, Peter Wipf
Hydrophosphination of bicyclo[1.1.0]butyl nitriles with phosphine boranes and phosphites provided novel cyclobutyl-P derivatives. The reaction generally favors the syn-diastereomer, and the nitrile can be reduced and converted to other functional groups, thus enabling the preparation of bidentate ligands that access new conformational space by virtue of their attachment to the torsionally malleable but sterically restrictive cyclobutane scaffold. The enantioselective hydrogenation of dehydrophenylalanine using a bidentate phosphine-phosphite ligand illustrates the synthetic utility of the newly prepared scaffold...
September 2, 2016: Organic Letters
https://www.readbyqxmd.com/read/27352236/diverse-reactivity-of-borenium-cations-with-n-h-compounds
#7
Marc Devillard, Sonia Mallet-Ladeira, Ghenwa Bouhadir, Didier Bourissou
The Ph2P-stabilized borenium reacts cleanly with PhNH2, NH3 and HNTf2 to give a variety of boron compounds, namely the amino-substituted borenium (substitution reaction at B), the neutral phosphine-borane , the mixed P/N-stabilized boronium and the dicationic boron species . Remote modulation of the Lewis acidity at boron has been studied by preparing the related iPr2P-stabilized borenium and reacting it with dihydrogen.
July 7, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27320239/iridium-catalysed-dehydrocoupling-of-aryl-phosphine-borane-adducts-synthesis-and-characterisation-of-high-molecular-weight-poly-phosphinoboranes
#8
Ursula S D Paul, Holger Braunschweig, Udo Radius
The thermal dehydrogenative coupling of aryl phosphine-borane adducts with iridium complexes bearing a bis(phosphinite) pincer ligand is reported. This catalysis produces high molecular weight poly(phosphinoboranes) [ArPH-BH2]n (Ar = Ph, (p)Tol, Mes). Furthermore, we investigated the reactivity of these pincer complexes towards primary phosphines and their respective borane adducts on a stoichiometric scale.
June 30, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27283866/reactivity-studies-on-a-diazadiphosphapentalene
#9
Jingjing Cui, Yongxin Li, Rakesh Ganguly, Rei Kinjo
The reactivity of diazadiphosphapentalene 1 towards various substrates was investigated. Reaction of 1 with ammonia-borane resulted in transfer hydrogenolysis concomitantly with the cleavage of a P-N bond. By treatment of 1 with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), oxidation took place at one of the phosphorus atoms of 1, and a P(V) /P(III) mixed-valence derivative was isolated. At the same time, it was demonstrated that only one of the phosphorus atoms in 1 behaves as an electron donor for electrophiles and Lewis acids...
July 11, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27264910/intracellular-disulfide-reduction-by-phosphine-borane-complexes-mechanism-of-action-for-neuroprotection
#10
Nicholas J Niemuth, Alex F Thompson, Megan E Crowe, Christopher J Lieven, Leonard A Levin
Phosphine-borane complexes are novel cell-permeable drugs that protect neurons from axonal injury in vitro and in vivo. These drugs activate the extracellular signal-regulated kinases 1/2 (ERK1/2) cell survival pathway and are therefore neuroprotective, but do not scavenge superoxide. In order to understand the interaction between superoxide signaling of neuronal death and the action of phosphine-borane complexes, their biochemical activity in cell-free and in vitro assays was studied by electron paramagnetic resonance (EPR) spectrometry and using an intracellular dithiol reporter that becomes fluorescent when its disulfide bond is cleaved...
October 2016: Neurochemistry International
https://www.readbyqxmd.com/read/27181026/synergistic-effects-in-ambiphilic-phosphino-borane-catalysts-for-the-hydroboration-of-co2
#11
Anis Tlili, Arnaud Voituriez, Angela Marinetti, Pierre Thuéry, Thibault Cantat
The benefit of combining both a Lewis acid and a Lewis base in a catalytic system has been established for the hydroboration of CO2, using ferrocene-based phosphine, borane and phosphino-borane derivatives.
June 18, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27145380/an-entry-to-stable-mixed-phosphine-osmium-nhc-polyhydrides
#12
María L Buil, Juan J F Cardo, Miguel A Esteruelas, Israel Fernández, Enrique Oñate
An entry to mixed phosphine-osmium-NHC polyhydride complexes is described, starting from the five-coordinate hydrido-alkylidyne compounds [OsHCl(≡CPh)(IPr)(PR3)]OTf (IPr = 1,3-bis(2,6-disopropylphenyl)imidazolylidene; OTf = CF3SO3; PR3 = P(i)Pr3 (1), PPh3 (2)). The experimental procedure involves the borylation of the Os-C triple bond of 1 and 2 with NaBH4 and the subsequent alcoholysis of the borylation products OsH2Cl(η(2)-H-BCH2Ph)(IPr)(PR3) (PR3 = P(i)Pr3 (3), PPh3 (4)) or OsH2(η(2):η(2):H2BCH2Ph)(IPr)(P(i)Pr3) (5)...
May 16, 2016: Inorganic Chemistry
https://www.readbyqxmd.com/read/27117834/ruthenium-complexes-of-p-stereogenic-phosphines-with-a-heterocyclic-substituent
#13
Pau Clavero, Arnald Grabulosa, Mercè Rocamora, Guillermo Muller, Mercè Font-Bardia
The synthesis via phosphine-boranes of 13 new optically pure P-stereogenic diarylphosphines P(Het)PhR (Het = 4-dibenzofuranyl (DBF), 4-dibenzothiophenyl (DBT), 4-dibenzothiophenyl-S,S-dioxide (DBTO2) and 1-thianthrenyl (TA); R = OMe, Me, i-Pr, Fc (ferrocenyl)) following the Jugé-Stephan method is described. The ligands were designed with the aim of having a heteroatom in a position capable of interacting with a metal upon coordination. The ligands and their precursors have been fully characterised, including the determination of two crystal structures of phosphine-boranes...
May 28, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/27063185/formation-of-a-unique-unsupported-hydridic-stannate-ii
#14
María Fernández-Millán, Lucy K Allen, Raúl García-Rodríguez, Andrew D Bond, Marta E G Mosquera, Dominic S Wright
The reaction of the amido-stannate LiSn(NMe2)3 with the phosphine-borane (t)Bu2PHBH3 gives the Sn(II) hydride [(Me2NH)2Li{BH3P((t)Bu)2}2Sn(H)]; the first example of a hydridic stannate(ii) that is not supported by transition metal or ligand bonding.
May 1, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/26997653/p4-functionalization-by-hydrides-direct-synthesis-of-p-h-bonds
#15
Koyel X Bhattacharyya, Sébastien Dreyfuss, Nathalie Saffon-Merceron, Nicolas Mézailles
A direct method for white phosphorus functionalization by hydride sources is presented. Excess BH4(-) in n-butylamine produces HP4(-) as the major P-containing species. Reaction with LiBEt3H forms the borane-stabilized phosphanide Li(PH2)(BEt3)2, which may be used to synthesize various phosphines. Triethylborane may be replaced by BH3, resulting in the formation of LiPH2(BH3)2.
April 14, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/26871613/relative-reactivity-of-stable-ligated-boranes-and-a-borohydride-salt-in-rhodium-ii-catalyzed-boron-hydrogen-insertion-reactions
#16
Thomas H Allen, Dennis P Curran
Relative reactivities of a series of neutral ligated boranes L-BH3 (where L is NHC, amine, pyridine, or phosphine) and the cyanoborohydride anion have been assessed in Rh(II)-catalyzed B-H insertion reactions with methyl 2-phenyl-2-diazoacetate. Stable α-boryl ester products were isolated by flash chromatography in all cases except for the salt product from cyanoborohydride. All of the substrates were either comparable to or more reactive than 1,4-cyclohexadiene, which is one of the most reactive substrates in C-H insertion reactions...
March 4, 2016: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/26824249/facile-insertion-of-rh-and-ir-into-a-boron-phenyl-bond-leading-to-boryl-bis-phosphine-pbp-pincer-complexes
#17
Wei-Chun Shih, Weixing Gu, Morgan C MacInnis, Samuel D Timpa, Nattamai Bhuvanesh, Jia Zhou, Oleg V Ozerov
The unexpectedly facile insertion of Rh or Ir into a B-Ph bond (reversible for Rh) converts a borane/bis(phosphine) precursor into a boryl/bis(phosphine) PBP pincer ligand. Interconversions between the boryl/borane/borate central functionality are demonstrated in reactions with dihydrogen.
February 24, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/26652066/the-hydroxyalkyl-moiety-as-a-protecting-group-for-the-stereospecific-alkylation-of-masked-secondary-phosphine-boranes
#18
Sébastien Lemouzy, Marion Jean, Laurent Giordano, Damien Hérault, Gérard Buono
The synthesis of functionalized tertiary phosphine-boranes has been developed via a chemodivergent approach from readily accessible (hydroxymethyl) phosphine-boranes under mild conditions. O-Alkylation or decarbonylative P-alkylation product could be exclusively obtained. The P-alkylation reaction was found to proceed in moderate to very good yields and very high enantiospecificity (es >95%) using a variety of alkyl halides as electrophiles. The configurational stability of the sodium phosphido-borane intermediate was also investigated and allowed a deeper understanding of the reaction mechanism, furnishing secondary phosphine-boranes in moderate yield and enantiopurity...
January 4, 2016: Organic Letters
https://www.readbyqxmd.com/read/26477668/stereospecific-s-n-2-p-reactions-novel-access-to-bulky-p-stereogenic-ligands
#19
Sílvia Orgué, Areli Flores-Gaspar, Maria Biosca, Oscar Pàmies, Montserrat Diéguez, Antoni Riera, Xavier Verdaguer
The stereospecific hydrolysis of bulky aminophosphine boranes is reported for the first time. The resulting phosphinous acid boranes, upon activation, undergo stereospecific nucleophilic substitution reaction at the phosphorous center with amine nucleophiles. The combination of these two processes provides a novel access to bulky P*-ligands.
December 25, 2015: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/26419539/palladium-ii-complexes-featuring-a-mixed-phosphine-pyridine-iminophosphorane-pincer-ligand-synthesis-and-reactivity
#20
Thibault Cheisson, Audrey Auffrant
An original mixed ligand (labelled L) of formula PPh2-CH2-Pyr-CH2-N[double bond, length as m-dash]PPh3, combining a pyridine core with phosphine and iminophosphorane, was synthesised. Its coordination with palladium(II) centers was studied. With [Pd(COD)Cl2], a cationic complex [LPdCl](Cl) 1, where L is coordinated in the pincer mode, was obtained. Chloride abstraction with silver salt in the presence of pyridine generated the dicationic complex [LPd(py)](BF4)2 (2). When reacting with a base such as potassium hexamethyldisilazane (KHMDS), 1 gave the neutral complex 3 [L*PdCl], wherein the benzylic position alpha to phosphine was selectively deprotonated, which induced dearomatisation of the pyridine ring...
February 7, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
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