Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

1980 ◽  
Vol 45 (8) ◽  
pp. 2219-2223 ◽  
Author(s):  
Marie Jakoubková ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Electron Density ◽  
Phosphorus Atom ◽  
Proton Acceptor ◽  
Trimethylsilyl Group ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

In-depth NMR and IR study of the proton transfer equilibrium between [{(MeC(CH2PPh2)3}Ru(CO)H2] and hexafluoroisopropanol

2001 ◽  
Vol 79 (5-6) ◽  
pp. 479-489 ◽  
Author(s):  
Vladimir I Bakhmutov ◽  
Ekaterina V Bakhmutova ◽  
Natalia V Belkova ◽  
Claudio Bianchini ◽  
Lina M Epstein ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Proton Transfer ◽  
Proton Transfer Reaction ◽  
Proton Donor ◽  
Strong Hydrogen Bond ◽  
Nmr Study ◽  
Ir Study

The (carbonyl)dihydride complex [(triphos)Ru(CO)H2] (2) has been synthesized by reaction of the ruthenate [(triphos)RuH3]K (triphos = MeC(CH2PPh2)3) with ethanol saturated with CO. A single crystal X-ray analysis and IR and NMR experiments have shown that 2 adopts in both the solid state and solution an octahedral coordination geometry with a facial triphos ligand, two cis terminal hydrides, and a terminal carbonyl. The reaction of hexafluoro-2-propanol (HFIP) with 2 has been studied in CH2Cl2 solution by IR and NMR spectroscopy. The proton donor interacts with a terminal hydride of 2 forming a rather strong hydrogen bond. The resulting H-bonded adduct [{(triphos)Ru(CO)(H)H}···{HOCH(CF3)2}] (2a) has fully been characterized by in situ NMR and IR techniques. Compound 2a is in equilibrium with the nonclassical η2-H2 complex [(triphos)Ru(CO)H(H2)]+ (2b), which can independently be prepared by protonation of 2 with a strong protic acid at low temperature. Unequivocal characterization of the dihydrogen complex (2b) has been achieved by a multifaceted spectroscopic investigation (Tobs1min = 0.005 s (200 MHz), JH,D [Formula: see text] 30 Hz, DQCC = 78.3 kHz). A combined IR and NMR study of the proton transfer reaction involving 2 and HFIP in CH2Cl2 to give, first, the H-bonded adduct (2a) and, then, the dihydrogen complex (2b) has demonstrated that all these species are in equilibrium in the temperature range from 190 to 260 K. The thermodynamic parameters for the formation of 2a have independently been determined by NMR and IR methods, while those for the formation of 2b have been obtained by IR spectroscopy. An energetic profile for the reaction sequence 2 [Formula: see text] 2a [Formula: see text] 2b is proposed and discussed.Key words: hydrides, hydrogen bonding, ruthenium, IR spectroscopy, NMR spectroscopy.

Time resolved growth of membrane stabilized silver NPs and their catalytic activity

RSC Advances ◽  
2014 ◽  
Vol 4 (103) ◽  
pp. 59379-59386 ◽  
Author(s):  
Sabyasachi Patra ◽  
Debasis Sen ◽  
Ashok K. Pandey ◽  
J. Bahadur ◽  
S. Mazumder ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Catalytic Activity ◽  
Growth Kinetics ◽  
Nanocomposite Membranes ◽  
Time Resolved ◽  
Catalytic Application ◽  
Silver Nps ◽  
First Time ◽  
Kinetics Of

Growth kinetics of membrane stabilized silver nanoparticles have been studied for the first time with time resolved in situ SAXS. The catalytic application of nanocomposite membranes thus formed has also been explored.

Diminished electron density in the Vaska-type rhodium(I) complextrans-[Rh(NCBH3)(CO)(PPh3)2]

2016 ◽  
Vol 72 (7) ◽  
pp. 514-517
Author(s):  
M. R. Galding ◽  
A. V. Virovets ◽  
I. V. Kazakov ◽  
M. Scheer ◽  
S. N. Smirnov ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectroscopy ◽  
Electron Density ◽  
Coupling Constants ◽  
X Ray Diffraction ◽  
Metathesis Reaction ◽  
Carbonyl Carbon ◽  
Carbonyl Ligand ◽  
X Ray ◽  
Nmr Data

Vaska-type complexes,i.e. trans-[RhX(CO)(PPh3)2] (Xis a halogen or pseudohalogen), undergo a range of reactions and exhibit considerable catalytic activity. The electron density on the RhIatom in these complexes plays an important role in their reactivity. Many cyanotrihydridoborate (BH3CN−) complexes of Group 6–8 transition metals have been synthesized and structurally characterized, an exception being the rhodium(I) complex. Carbonyl(cyanotrihydridoborato-κN)bis(triphenylphosphine-κP)rhodium(I), [Rh(NCBH3)(CO)(C18H15P)2], was prepared by the metathesis reaction of sodium cyanotrihydridoborate withtrans-[RhCl(CO)(PPh3)2], and was characterized by single-crystal X-ray diffraction analysis and IR,1H,13C and11B NMR spectroscopy. The X-ray diffraction data indicate that the cyanotrihydridoborate ligand coordinates to the RhIatom through the N atom in atransposition with respect to the carbonyl ligand; this was also confirmed by the IR and NMR data. The carbonyl stretching frequency ν(CO) and the carbonyl carbon1JC–Rhand1JC–Pcoupling constants of the Cipsoatoms of the triphenylphosphine groups reflect the diminished electron density on the central RhIatom compared to the parenttrans-[RhCl(CO)(PPh3)2] complex.

scholarly journals Tracing the Acetalization of Cyclohexanone in CO2-Expanded Alcohols by Attenuated Total Reflection Infrared Spectroscopy

2009 ◽  
Vol 63 (9) ◽  
pp. 1008-1014 ◽  
Author(s):  
Tsunetake Seki ◽  
Jean-Michel Andanson ◽  
Fabian Jutz ◽  
Alfons Baiker
Keyword(s):  
Ir Spectroscopy ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Znse Crystal ◽  
Promising Alternative ◽  
Practical Tool ◽  
Acidic Conditions ◽  
Kinetics Of

The CO2-catalyzed acetalization is regarded as a promising alternative to the conventional acid-catalyzed method from a viewpoint of green chemistry (C. A. Eckert et al., Ind. Eng. Chem. Res. 43, 2605 (2004)). We have applied in situ attenuated total reflection infrared (ATR-IR) spectroscopy for elucidating and monitoring the acetalization of cyclohexanone in CO2-expanded ethylene glycol and methanol at 50 °C and 3 MPa. The ATR-IR spectra of the reaction mixtures periodically recorded with a ZnSe crystal demonstrate that ATR-IR spectroscopy is a practical tool for tracing the kinetics of acetalizations in situ. In addition, the rate of CO2 dissolution as well as CO2 solubility into the cyclohexanone–alcohol mixtures could be evaluated from the CO2-v3-antisymmetric stretching band. The ZnSe ATR crystal, however, was corroded during longer use under the acidic conditions realized by the dissolution of CO2 in the alcohols. In contrast, the corrosion did not occur when a Ge crystal was used instead of a ZnSe crystal, and therefore the application of a Ge ATR crystal is recommended for continuous long-term experiments with these media.

Catalytic activity of rhodium(I) complexes containing poly(siloxy)alkyldiphenylphosphines

1980 ◽  
Vol 45 (7) ◽  
pp. 2100-2107 ◽  
Author(s):  
Vladimír Kavan ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Pressure ◽  
Catalyst Activity ◽  
Molar Ratio ◽  
Normal Hydrogen ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from di-μ.μ'-chloro-bis(dicyclooctenerhodium) and phosphine L (L = 2-(diethoxymethylsilyl)ethyldiphenylphosphine, 3-(diethoxymethylsilyl)propyldiphenylphosphine and their copolymers with diethoxydimethylsilane) have been studied at 64°C under normal hydrogen pressure. The dependence of the catalyst activity on the type of L( monomeric, polymeric, supported on silica) has been examined. The effects of Rh : P molar ratio, the concentration of phosphine groups in siloxane copolymers and of the method of catalyst fixation to support on catalyst performance are discussed.

scholarly journals In-Situ FT-IR Spectroscopy Investigation of CH4 and CO2 Reaction

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 131 ◽  
Author(s):  
Yongjun Liu ◽  
Nan Cui ◽  
Penglong Jia ◽  
Wei Huang
Keyword(s):  
Catalytic Activity ◽  
Ir Spectroscopy ◽  
Atomic Hydrogen ◽  
Surface Reaction ◽  
Catalyst Surface ◽  
Active Hydrogen ◽  
Irreversible Effect ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

An exclusive trace of CH4 direct carboxylation with CO2 by a stepwise technology was investigated using in-situ FT-IR spectroscopy. The results showed that CH4 was dissociated to atomic hydrogen and M-CHx species on catalyst surface when it was first introduced in the system, then CO2 was inserted into the intermediate to direct carboxylate. Finally, the subsequent adsorption of CH4 provided active hydrogen for the species of previous surface reaction, thus leading to the formation of the product. It was also found that the first introduction of CO2 on the surface of the “clean” catalyst might likely react with surface H species, which had an irreversible effect on the catalytic activity of CH4.

A Novel Gold Nanoparticle/Poly(AMPS-co-HEMA) Composite Hydrogel for Selective Catalysis

2011 ◽  
Vol 399-401 ◽  
pp. 704-707 ◽  
Author(s):  
Ke Ping Wang ◽  
Song Bai Lin ◽  
Na Na Wang ◽  
Ai Ru Ke
Keyword(s):  
Catalytic Activity ◽  
Reduction Reaction ◽  
Hydrogenation Rate ◽  
Processing Stage ◽  
Composite Gel ◽  
Growth Method ◽  
Selective Catalysis ◽  
Kinetics Of ◽  
Controllable Preparation

A modified seed-mediated growth method was developed for in situ controllable preparation of gold nanoparticles (GNPs) within P(AMPS-co-HEMA) hydrogel networks. When the time of cycles absorbing procedure increased in mother solutions under given temperature during the processing stage, the number of GNPs was significantly increased and networks were utilized for in situ nanoparticles synthesis by reduction of glod ion absorbed. TEM images confirmed that GNPs were between 100 and 200 nm in size and distributed uniformly in gel. The network embedded GNPs also endows the composite gel with selective catalytic activity for selective catalysis in the reduction of nitro compound (2-NP, 3-NP and 4-NP). The kinetics of the reduction reaction were investigated under the same condition, the result showed the GNPs gel system was found to have an excellent catalytic activity and high conversion for 4-NP reduction among nitrophenol homologue, the nitrophenol hydrogenation rate got to 6.63 mol/g min for reducing of 4-NP compared to 3.69 mol/g min, the rate of 2-NP. It was almost zero for 3-NP implying no catalytic activity, even though they were isomeride.

scholarly journals Kinetics of Methane Hydrate Replacement with Carbon Dioxide and Nitrogen Gas Mixture Using in Situ NMR Spectroscopy

2015 ◽  
Vol 49 (3) ◽  
pp. 1964-1971 ◽  
Author(s):  
Minjun Cha ◽  
Kyuchul Shin ◽  
Huen Lee ◽  
Igor L. Moudrakovski ◽  
John A. Ripmeester ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Nmr Spectroscopy ◽  
Methane Hydrate ◽  
Gas Mixture ◽  
Nitrogen Gas ◽  
Kinetics Of ◽  
In Situ Nmr Spectroscopy ◽  
In Situ Nmr

In situ study of electron beam-induced chemical vapor deposition of Au in an environmental TEM

1995 ◽  
Vol 53 ◽  
pp. 256-257
Author(s):  
J. Drucker ◽  
R. Sharma ◽  
J. Kouvetakis ◽  
K.H.J. Weiss
Keyword(s):  
Electron Beam ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Quantum Effect ◽  
Line Drawing ◽  
Chemical Vapor ◽  
Environmental Cell ◽  
Engineering Changes ◽  
Kinetics Of

Patterning of metals is a key element in the fabrication of integrated microelectronics. For circuit repair and engineering changes constructive lithography, writing techniques, based on electron, ion or photon beam-induced decomposition of precursor molecule and its deposition on top of a structure have gained wide acceptance Recently, scanning probe techniques have been used for line drawing and wire growth of W on a silicon substrate for quantum effect devices. The kinetics of electron beam induced W deposition from WF6 gas has been studied by adsorbing the gas on SiO2 surface and measuring the growth in a TEM for various exposure times. Our environmental cell allows us to control not only electron exposure time but also the gas pressure flow and the temperature. We have studied the growth kinetics of Au Chemical vapor deposition (CVD), in situ, at different temperatures with/without the electron beam on highly clean Si surfaces in an environmental cell fitted inside a TEM column.

In situ observation of the martensitic transformation in (Mg,Y)-PSZ

1986 ◽  
Vol 44 ◽  
pp. 500-501
Author(s):  
R-R. Lee
Keyword(s):  
Martensitic Transformation ◽  
High Strength ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Considerable Potential ◽  
Transmission Electron ◽  
Structural Applications ◽  
Applied Stresses ◽  
Kinetics Of

Partially-stabilized ZrO2 (PSZ) ceramics have considerable potential for advanced structural applications because of their high strength and toughness. These properties derive from small tetragonal ZrO2 (t-ZrO2) precipitates in a cubic (c) ZrO2 matrix, which transform martensitically to monoclinic (m) symmetry under applied stresses. The kinetics of the martensitic transformation is believed to be nucleation controlled and the nucleation is always stress induced. In situ observation of the martensitic transformation using transmission electron microscopy provides considerable information about the nucleation and growth aspects of the transformation.

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