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Phosphine boran

Zheng-Wang Qu, Hui Zhu, Stefan Grimme
Extensive DFT calculations provide detailed mechanistic insights into the metal-free reduction of phosphine oxide Ph3P=O using chlorination reagents O=CClX (X = COCl, Cl, OCCl3 and Ph) and H2. Fast nucleophilic attack to the P=O group oxygen is favored by exergonic CO2 release to form phosphonium Ph3PCl+ and chloride Cl-, which may slowly cleave H2 via an unstable HPh3PCl complex yielding Ph3PH+ and Cl- ions in solution. Moderate heating is required to accelerate the slow H2-activation step and to eliminate HCl to form phosphine Ph3P instead of Ph3PH+Cl- salt as the desired product...
February 13, 2019: Chemistry: a European Journal
Shawn E Wright, Stephanie Richardson-Solorzano, Tiffany N Stewart, Christopher D Miller, Kelsey C Morris, Christopher J A Daley, Timothy B Clark
Ambiphilic molecules, which contain a Lewis base and Lewis acid, are of great interest based on their unique ability to activate small molecules. Phosphine boronates are one class of these substrates that have interesting catalytic activity. Direct access to these phosphine boronates is described through the iridium-catalyzed C-H borylation of phosphines. An unconventional cationic iridium catalyst was identified as optimal for a range of phosphines, providing good yields and selectivity across a diverse class of phosphine boronates (isolated as the borane-protected phosphine)...
January 14, 2019: Angewandte Chemie
Tom E Stennett, Rüdiger Bertermann, Holger Braunschweig
Sterically unencumbered diborenes based on a benzylphosphine chelate undergo diboration reactions with bis(catecholato)diboron in the absence of a catalyst to yield tetraboranes. The symmetrical diborenes studied undergo 1,2-diborations, whereas an unsymmetrical derivative was found to yield a triborylborane-phosphine adduct as the result of a formal 1,1-diboration. A related borylborylene compound also underwent a 1,2-diboration to produce a borylene-borane adduct.
October 2, 2018: Angewandte Chemie
Mariano Méndez, Andrés Cedillo
The chemical reactivity of a set of borophosphines of the general formula R2 B-G-PY2 , where G is the connector group between the Lewis acidic site, a borane group, and the Lewis basic site, a phosphine fragment, is theoretically investigated through their Lewis acidity and Lewis basicity, as well as the location of the Fukui function and the shape of the molecular electrostatic potential. The role of some global reactivity descriptors, like the vertical ionization potential, I, and the vertical electron affinity, A, is also analyzed in order to gain a deeper insight on the intrinsic chemical reactivity of these borophosphines...
August 17, 2018: Journal of Molecular Modeling
Samantha L Apps, Andrew J P White, Philip W Miller, Nicholas J Long
The preparation and reactivity of a novel molybdenum dinitrogen complex supported by a nitrogen-centred tripodal phosphine ligand (N-triphos, N(CH2PPh2)3, NP3Ph) are reported. Reaction of N-triphos with [MoX3(THF)3] (X = Cl, Br, I) gave the Mo(iii) complex [MoX3(κ2-NP3Ph)(THF)] (1), where bidentate N-triphos coordination was observed. Reduction of this complex in the presence of dppm (bis(diphenylphosphino)methane) gave the dinitrogen complex [Mo(N2)(dppm)(κ3-NP3Ph)] (2), which exhibits moderate dinitrogen activation...
August 21, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Lucy C Brown, James M Hogg, Mark Gilmore, Leila Moura, Silvia Imberti, Sabrina Gärtner, H Q Nimal Gunaratne, Ruairi J O'Donnell, Nancy Artioli, John D Holbrey, Małgorzata Swadźba-Kwaśny
The presence of the weakly-associated encounter complex in the model frustrated Lewis pair solution (FLP): tris(tert-butyl)phosphine (P(t Bu)3 ) and tris(pentafluorophenyl)borane (BCF) in benzene, was confirmed via PB correlation analysis from neutron scattering data. On average, ca. 5% of dissolved FLP components were in the associated state. NMR spectra of the FLP in benzene gave no evidence of such association, in agreement with earlier reports and the transient nature of the encounter complex. In contrast, the corresponding FLP solution in the ionic liquid, 1-decyl-3-methylimidazolium bistriflamide, [C10 mim][NTf2 ], generated NMR signals that can be attributed to formation of encounter complexes involving over 20% of the dissolved species...
August 14, 2018: Chemical Communications: Chem Comm
Milan R Milovanović, Jelena M Andrić, Vesna B Medaković, Jean Pierre Djukic, Sneǽana D Zarić
The interactions between phosphines and boranes in crystal structures have been investigated by analyzing data from the Cambridge Structural Database (CSD). The interactions between phosphines and boranes were classified into three types; two types depend on groups on the boron atom, whereas the third one involves frustrated Lewis pairs (FLPs). The data enabled geometric parameters in structures to be compared with phosphine-borane FLPs with classical Lewis pairs. Most of the crystal structures (78.1%) contain BH3 as the borane group...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
Kevin M Szkop, Diya Zhu, Lauren E Longobardi, Julian Heck, Douglas W Stephan
Phosphine oxidation by MesCNO is rapid; however, an FLP strategy intercepts the 1,3 addition products including [MesC(R3P)NOB(C6F5)3] (R = Ph 1, p-tol 2), [MesC(Mes2PH)NOB(C6F5)3] 3 (MesC(NOB(C6F5)3)Ph2P)2(CH2)n (n = 2: 4, 3: 5) and [MesC(Ph3P)NOB(C6F4H)3] 6. These species are shown to react with tBuOK or [Bu4N]F permitting the oxidation to proceed via a process involving borane dissociation. Similarly, the equilibrium established by 1 with B(C6F4H)3 and 6 with B(C6F5)3 provides experimental support for the "Cummins mechanism" for these phosphine oxidations...
July 10, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Liang Chen, Renjie Liu, Qiang Yan
Frustrated Lewis pairs (FLP), a couple comprising a sterically encumbered Lewis acid and Lewis base, can offer latent reactivity for activating inert gas molecules. However, their use as a platform for fabricating gas-responsive materials has not yet developed. Merging the FLP concept with polymers, we report a new generation CO2 -responsive system, differing from the first-generation ones based on an acid-base equilibrium mechanism. Two complementary Lewis acidic and basic block copolymers, installing bulky borane- and phosphine-containing blocks, were built as the macromolecular FLP...
July 20, 2018: Angewandte Chemie
Brian R Nichols, Novruz G Akhmedov, Jeffrey L Petersen, Brian V Popp
Lewis basic substrates, such as vinylphosphines and enamines, can be problematic for transition-metal catalysed hydrofunctionalization reactions due to their propensity to ligate and deactivate transition-metal catalysts as well as form direct Lewis adducts with reaction partners. While exploring rhodium-catalyzed hydroboration of diphenylvinylphosphine with pinacolborane, we found that a high degree of regiocontrol could be achieved without the need to diminish the Lewis basicity of the phosphine by oxidation or prior-protection...
June 25, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Tetiana Krachko, Emmanuel Nicolas, Andreas W Ehlers, Martin Nieger, J Chris Slootweg
Treatment of the preorganized frustrated Lewis pairs (FLPs) tBu2 PCH2 BPh2 (1) and o-Ph2 P(C6 H4 )BCat (Cat=catechol) (4) with 2-methyloxirane, 2-phenyloxirane and 2-(trifluoromethyl)oxirane resulted in epoxide ring-opening to yield the six- and seven-membered heterocycles 2 a-c and 5 a-c, respectively. These zwitterionic products were characterized spectroscopically, and compounds 2 a, 2 b, 5 a and 5 c were structurally characterized by single-crystal X-ray structure analyses. Based on computational and kinetic studies, the mechanism of these reactions was found to proceed via activation of the epoxide by the Lewis acidic borane moiety followed by nucleophilic attack of the phosphine of a second FLP molecule...
August 27, 2018: Chemistry: a European Journal
Petra Vasko, Ili A Zulkifly, M Ángeles Fuentes, Zhenbo Mo, Jamie Hicks, Paul C J Kamer, Simon Aldridge
A dimethylxanthene-based phosphine/borane frustrated Lewis pair (FLP) is shown to effect reversible C-H activation, cleaving phenylacetylene, PhCCH, to give an equilibrium mixture of the free FLP and phosphonium acetylide in CD2 Cl2 solution at room temperature. This system also reacts with B-H bonds although in a different fashion: reactions with HBpin and HBcat proceed via C-B/B-H metathesis, leading to replacement of the -B(C6 F5 )2 Lewis acid component by -Bpin/-Bcat, and transfer of HB(C6 F5 )2 to the phosphine Lewis base...
July 20, 2018: Chemistry: a European Journal
Matthew J Chalkley, Trevor J Del Castillo, Benjamin D Matson, Jonas C Peters
Substrate selectivity in reductive multielectron/proton catalysis with small molecules such as N2 , CO2 , and O2 is a major challenge for catalyst design, especially where the competing hydrogen evolution reaction (HER) is thermodynamically and kinetically competent. In this study, we investigate how the selectivity of a tris(phosphine)borane iron(I) catalyst, P3 B Fe+ , for catalyzing the nitrogen reduction reaction (N2 RR, N2 -to-NH3 conversion) versus HER changes as a function of acid p Ka . We find that there is a strong correlation between p Ka and N2 RR efficiency...
May 16, 2018: Journal of the American Chemical Society
Albert Gallen, Sílvia Orgué, Guillermo Muller, Eduardo C Escudero-Adán, Antoni Riera, Xavier Verdaguer, Arnald Grabulosa
Both enantiomers of the optically pure Secondary Phosphine Oxide (SPO) t-BuMeP(O)H (1) have been obtained by deboronation of phosphinous acid-borane t-BuMeP(O)H·BH3 (3) with HBF4 followed by hydrolysis of the intermediate adduct t-BuMeP(O)H·BF3 (1·BF3), which has been isolated and crystallographically characterised. Complexes [MCl(COD)(κP-(R)-1)] (M = Ir, Rh; 4 and 7 respectively) have been detected in solution but could not be isolated while trans-[RhCl(CO)(κP-(S)-1)2] (9) has been successfully obtained in good yield...
April 17, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Jie Guang, Romain Duwald, Jacques Maddaluno, Hassan Oulyadi, Sami Lakhdar, Annie-Claude Gaumont, Anne Harrison-Marchand
The synthesis and identification of unprecedented gem-dianionic phosphorus compounds, that is, gem-dilithium phosphido-boranes Li2 [RP⋅BH3 ], with R=Ph or Cy, are reported in THF solution. These were obtained by double deprotonation of the corresponding primary phosphine-borane precursors RPH2 ⋅BH3 . Their in-depth structural study, based on multinuclear (1 H, 6 Li, 7 Li, 11 B, 13 C, 31 P) mono- and bi-dimensional NMR analyses, indicates a strong influence of the phosphorus substituent on the structure of the gem-dianionic phosphorus structure; a monomeric arrangement was obtained when R=phenyl, whereas a cyclic oligomer was observed for R=cyclohexyl...
May 7, 2018: Chemistry: a European Journal
Nan Ding, Junqi Xu, Qi Zhang, Jianwei Su, Yu Gao, Xing Zhou, Tianyou Zhai
The p-n junction is one important and fundamental building block of the optoelectronic age. However, electrons and holes will be severely scattered in heterostructures led by the grain boundary at the alloy interface between two dissimilar semiconductors. In this work, we present boron phosphide (BP) nanowires with artificially controllable carrier type for the fabrication of homojunctions via adjusting borane/phosphine ratio during the deposition process, both prove high crystallization with fewer impurities...
March 28, 2018: ACS Applied Materials & Interfaces
Nathan T Coles, Ruth L Webster
Catalytic dehydrocoupling methodologies, whereby dihydrogen is released from a substrate (or intermolecularly from two substrates) is a mild and efficient method to construct main group element-main group element bonds, the products of which can be used in advanced materials, and also for the development of hydrogen storage materials. With growing interest in the potential of compounds such as ammonia-borane to act as hydrogen storage materials which contain a high weight% of H2 , along with the current heightened interest in base metal catalyzed processes, this review covers recent developments in amine and phosphine dehydrocoupling catalyzed by iron complexes...
December 2017: Israel Journal of Chemistry
Lisa Vondung, Lukas Alig, Monika Ballmann, Robert Langer
Easy-to-prepare η2 -coordinated phosphine-borane ligands are demonstrated to liberate hydrogen upon treatment with different σ-donor/π-acceptor ligands (CO, tBuNC, CN- ). Depending on the utilized ancillary ligand, different reaction pathways are observed, ranging from simple hydride protonation to iron-boron bond formation and subsequent rearrangement to pincer-type ligands based on a tricoordinate boron centre. The last-named reactivity is in line with a formal umpolung at the boron centre from a Lewis acidic borane to a Lewis basic boron-based donor ligand...
August 22, 2018: Chemistry: a European Journal
Wei Meng, Xiangqing Feng, Haifeng Du
The use of frustrated Lewis pairs is an extremely important approach to metal-free hydrogenations. In contrast to the rapid growth of catalytic reactions, asymmetric hydrogenations are far less developed due to a severe shortage of readily available chiral frustrated Lewis pair catalysts with high catalytic activities and selectivities. Unlike the stable Lewis base component of frustrated Lewis pairs, the moisture-sensitive boron Lewis acid component is difficult to prepare. The development of convenient methods for the quick construction of chiral boron Lewis acids is therefore of great interest...
January 16, 2018: Accounts of Chemical Research
Mio Matsumura, Mizuki Yamada, Atsuya Muranaka, Misae Kanai, Naoki Kakusawa, Daisuke Hashizume, Masanobu Uchiyama, Shuji Yasuike
The parent benzophospholo[3,2- b ]indole was prepared by the reaction of dichlorophenylphosphine with a dilithium intermediate, which was prepared in two steps from 2-ethynyl- N , N -dimethylaniline. Using the obtained benzophosphole-fused indole as a common starting material, simple modifications were carried out at the phosphorus center of the phosphole, synthesizing various functionalized analogs. The X-ray structure analysis of trivalent phosphole and phosphine oxide showed that the fused tetracyclic moieties are planar...
2017: Beilstein Journal of Organic Chemistry
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