boron and phosphine

The synthesis of salts with the [B(CF(3))(4)](-) anion has been the starting point for new developments in the field of trifluoromethylboron chemistry. In contrast to the previous syntheses of (CF(3))(n)B derivatives (n=1-3), achieved exclusively by CF(3) transfer, the synthesis of the [B(CF(3))(4)](-) anion was accomplished by fluorination of the [B(CN)(4)](-) anion with ClF or ClF(3) in anhydrous HF. Owing to its thermal and chemical stability, [B(CF(3))(4)](-) is an attractive weakly coordinating anion. However, in concentrated sulfuric acid one of the four CF(3) groups is solvolyzed to a CO ligand to yield the neutral borane carbonyl (CF(3))(3)BC[triple bond]O. It has been shown that the borane carbonyl compound is a versatile synthetic building block, and numerous reactions have been investigated. The addition of nucleophiles to the C atom of the CO ligand is favored, and examples for new derivatives are the anions [(CF(3))(3)BC[triple bond]Pnic](-) (Pnic=N, P, As). Under certain conditions, ligand-exchange reactions are also observed, for example, the formation of (CF(3))(3)BN[triple bond]CH. Finally, the borane carbonyl compound is a component of the conjugated Brønsted-Lewis superacid HF/(CF(3))(3)BCO.

Topics: Alcohols; Amines; Ammonia; Boranes; Borates; Boron; Chalcogens; Hydrofluoric Acid; Ketones; Phosphines

Herein, we present a range of substrates that undergo hydrogen isotope exchange with an iridium(I) N-heterocyclic carbene/phosphine complex bearing the less coordinating tetrakis[3,5-bis(trifluoromethyl)phenyl]borate counterion and compare these with labelling using the equivalent, more established hexafluorophosphate complex. The changes in reactivity and selectivity of these complexes in a series of solvents are examined. Copyright © 2016 John Wiley & Sons, Ltd.

Topics: Boron; Catalysis; Deuterium; Iridium; Organometallic Compounds; Phosphines; Tritium

Transmetalation is a key elementary reaction of many important catalytic reactions. Among these, 1,4-addition of arylboronic acids to organic acceptors such as α,β-unsaturated ketones has emerged as one of the most important methods for asymmetric C-C bond formation. A key intermediate for the B-to-Rh transfer arising from quaternization on a boronic acid by a Rh-bound hydroxide (the active catalyst) has been proposed. Herein, DFT calculations (IEFPCM/PBE0/DGDZVP level of theory) establish the viability of this proposal, and characterize the associated pathways. The delivery of phenylboronic acid in the orientation suited for the B-to-Rh transfer from the very beginning is energetically preferable, and occurs with expulsion of Rh-coordinated water molecules. For the bulkier binap ligand, the barriers are higher (particularly for the phenylboronic acid activation step) due to a less favourable entropy term to the free energy, in accordance with the experimentally observed slower transmetalation rate.

Topics: Alkadienes; Boron; Boronic Acids; Catalysis; Hydroxides; Ketones; Ligands; Molecular Structure; Organometallic Compounds; Phosphines; Quantum Theory; Rhodium

Site-selective C-H borylation of quinoline derivatives at the C8 position has been achieved by using a heterogeneous Ir catalyst system based on a silica-supported cage-type monophosphane ligand SMAP. The efficient synthesis of a corticotropin-releasing factor1 (CRF1) receptor antagonist based on a late-stage C-H borylation strategy demonstrates the utility of the C8 borylation reaction.

Topics: Boron; Carbon; Catalysis; Hydrogen; Iridium; Ligands; Phosphines; Quinolines; Receptors, Corticotropin-Releasing Hormone; Silicon Dioxide

The FeNi alloy nanoparticles (FeNi and BFeNi) supported on natural halloysite nanotubes (HNTs) were prepared for catalytic decomposition of toxic phosphine (PH₃) to yellow phosphorus and hydrogen. The Fourier transform infrared spectroscopy, X-ray diffraction, inductively coupled plasma, scanning electron microscope, and hydrogen temperature-programmed reduction tests were carried out to characterize the physicochemical properties of HNTs and the prepared nano-catalysts. Nearly 100% PH₃ was decomposed into yellow phosphorus and hydrogen at 420 °C with prepared FeNi/HNTs catalysts. Metallic Ni and Fe₃O₄ could be the catalytic active sites in FeNi/HNTs for PH₃ decomposition under the low temperature. The boron (B) additives decrease the catalytic activity of FeNi/HNTs for PH₃ decomposition due to the formation of the spinal NiFe₂O₄ and Fe₂B which replace the active Fe₃O₄ and metallic Ni in catalysts. The developed FeNi/HNTs are low-cost and effective catalysts for air-pollution control and recycle of the hazardous waste PH₃ gas in industry.

Topics: Alloys; Aluminum Silicates; Boron; Catalysis; Clay; Ferrosoferric Oxide; Gases; Hydrogen; Metal Nanoparticles; Nanotubes; Nickel; Phosphines; Phosphorus; Temperature

A Cu-catalyzed regioselective and stereospecific aminoboration of styrenes with bis(pinacolato)diboron and O-benzoyl-N,N-dialkylhydroxylamines that delivers the corresponding β-aminoalkylboranes in good yields has been developed. The Cu catalysis enables introduction of both amine and boron moieties to C-C double bonds simultaneously in a syn fashion. Moreover, the use of a chiral biphosphine ligand, (S,S)-Me-Duphos, provides a catalytic enantioselective route to optically active β-aminoalkylboranes.

Topics: Amines; Boron; Catalysis; Copper; Hydroxylamines; Molecular Structure; Phosphines; Stereoisomerism; Styrenes

A rhodium-catalyzed dehydrogenative borylation of cyclic alkenes is described. This reaction provides direct access to cyclic 1-alkenylboronic acid pinacol esters, useful intermediates in organic synthesis. Suzuki-Miyaura cross-coupling applications are also presented.

Topics: Boron; Catalysis; Cycloparaffins; Phosphines; Rhodium

We investigated the influence of a substituent and a Lewis base on boron upon the thermodynamic stability of metal complexes of borane-Lewis base adducts, [M(CO)5(eta1-BH(2)R.L)] (M=Cr, W) and [CpMn(CO)2(eta1-BH2R.L)], where R=Cl, I, m-C6H4F, Ph, H, Me, Et; L=PMe3, PPh3, NMe3, quinuclidine. In these compounds, the stability of the metal-borane linkage was enhanced by increasing the electron-releasing ability of the substituent on boron. A stronger base L additionally stabilized the complexes. The strength of the borane-metal interaction is thus mainly ascribed to the electron donation from the BH sigma orbital to metal rather than the back-donation into the BH sigma* orbital. This result supports the bonding model for the B-H-M linkage in the borane complexes suggested by MO calculations, where the borane-to-metal electron donation is predominant while the metal back-donation into the BH sigma* orbital is negligible. Such a stability trend of the borane complexes makes a sharp contrast to that of many silane and dihydrogen complexes.

Topics: Amines; Boranes; Boron; Carbon Monoxide; Chromium Compounds; Hydrogen; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Manganese Compounds; Models, Molecular; Molecular Conformation; Phosphines; Protons; Temperature; Thermodynamics

Sediment from a representative and ecologically important backwater wetland under the influence of River Tisza (Hungary) was chemically characterized for sediment pollutants. Phosphine production potential, methyl mercury, mercury, and other heavy metals were determined along with other sediment chemical and physical properties. The wetland site, which is relatively isolated, represents an important bird reserve and nature conservation area. Methyl mercury and total mercury content was also low reflecting little mercury pollution in the sediment. Results of heavy metal analysis showed that only copper was elevated with concentration slightly above the reported levels considered excessive in soils and sediments. Other sediment properties were in normal range except boron content, which was high. Results show sediment were relatively unpolluted but should be routinely monitored to insure that this ecologically important area remains environmentally safe for future generation.

Topics: Boron; Chromatography, Gas; Environmental Monitoring; Environmental Pollutants; Geologic Sediments; Hungary; Mercury; Phosphines; Rivers; Spectrometry, Fluorescence; Spectrophotometry, Atomic