292-64-8Relevant articles and documents
Solid-State Chemistry of Molecular Metal Oxide Clusters. Ortho Metalation and Hydrogen Transport in 3PW12O40 Probed by 31P NMR Long-Range Deuterium Isotope Effects
Siedle, A. R.,Newmark, R. A.
, p. 2058 - 2062 (1989)
Deuterium isotope effects on 31P shielding that are large relative to the accuracy with which they can be measured are reported.In (Ph3P)2IrH2(dmf)2+, substitution of one 2H for 1H at the IR-H or at the ortho position in the Ph3P ligand leads to two- and three-bond isotope shifts of +0.094 and -0.110 ppm, respectively, with the effect being defined as 2H form)-δ(1H form)>.The ortho-deuterium effects on 31P for Ph3P, Ph3PO, Ph3PMe+I-, and (Ph3P)2Ir(C8H12)+ are -0.110, -0.096, -0.035, and -0.077 ppm, respectively.These long-range isotope effects are used to demonstrate a thermally activated, solid-state exchange of deuterium between iridium and only in the ortho positions of the Ph3P ligands in 3PW12O40.There occurs, additionally, an intermolecular hydrogen-deuterium exchange process.Slow exchange with c-C6D12 leads to incorporation of the deuterium label in the Ph3P rings.
In situ formed "weakly ligated/labile ligand" iridium(0) nanoparticles and aggregates as catalysts for the complete hydrogenation of neat benzene at room temperature and mild pressures
Bayram, Ercan,Zahmakiran, Mehmet,Oezkar, Saim,Finke, Richard G.
, p. 12455 - 12464 (2010)
"Weakly ligated/labile ligand" nanoparticles, that is nanoparticles where only weakly coordinated ligands plus the desired catalytic reactants are present, are of fundamental interest. Described herein is a catalyst system for benzene hydrogenation to cyclohexane consisting of "weakly ligated/labile ligand" Ir(0) nanoparticles and aggregates plus dry-HCl formed in situ from commercially available [(1,5-COD)IrCl]2 plus 40 ± 1 psig (～2.7 atm) H2 at 22 ± 0.1 °C. Multiple control and other experiments reveal the following points: (i) that this catalyst system is quite active with a TOF (turnover frequency) of 25 h-1 and TTO (total turnovers) of 5250; (ii) that the BF 4- and PF6- iridium salt precursors, [(1,5-COD)Ir(CH3CN)2]BF4 and [(1,5-COD)Ir(CH3CN)2]PF6, yield inferior catalysts; (iii) that iridium black with or without added, preformed HCl cannot achieve the TOF of 25 h-1 of the in situ formed Ir(0)/dry-HCl catalyst. However and importantly, CS2 poisoning experiments yield the same activity per active iridium atom for both the Ir(0)/dry-HCl and Ir black/no-HCl catalysts (12.5 h-1 Ir1-), but reveal that the Ir(0)/dry-HCl system is 10-fold more dispersed compared to the Ir(0) black catalyst. The simple but important and key result is that "weakly ligated/labile ligand" Ir(0) nanoparticles and aggregates have been made in situ as demonstrated by the fact that they have identical, per exposed Ir(0) activity within experimental error to Ir(0) black and that they have no possible ligands other than those desired for the catalysis (benzene and H2) plus the at best poor ligand HCl. As expected, the in situ catalyst is poorly stabilized, exhibiting only 60% of its initial activity in a second run of benzene hydrogenation and resulting in bulk metal precipitation. However, stabilization of the Ir(0) nanoparticles with a ca. 2-fold higher catalytic activity and somewhat longer lifetime for the complete hydrogenation of benzene was accomplished by supporting the Ir(0) nanoparticles onto zeolite-Y (TOF of 47h-1 and 8600 TTOunder otherwise identical conditions). Also reported is the interesting result that Cl- (present as Proton Sponge ·H+Cl-) completely poisons benzene hydrogenation catalysis, but not the easier cyclohexene hydrogenation catalysis under otherwise the same conditions, results that suggest different active sites for these ostensibly related hydrogenation reaction. The results suggest that synthetic routes to "weakly ligated/labile ligand" nanoparticles exhibiting improved catalytic performance is an important goal worthy of additional effort. 2010 American Chemical Society.
Pd Nanoparticles supported on MIL-101: An efficient recyclable catalyst in oxidation and hydrogenation reactions
Bhattacharjee, Samiran,Kim, Jun,Ahn, Wha-Seung
, p. 2546 - 2552 (2014)
Pd nanoparticles supported on the chromium terephthalate metal organic framework MIL-101 (Pd/MIL-101) in different loadings (0.9 and 4.5 wt%) have been successfully prepared through a simple Pd-acetate adsorption and reduction in acetone, and tested as catalyst for selected liquid phase oxidation and hydrogenation reactions. The materials were characterized by XRD, N2 adsorption-desorption isotherm, TEM, SEM-EDX and ICP analysis. The parent MIL-101 structure was found well preserved after formation of Pd nanoparticles and after catalytic reaction runs. The present catalyst afforded good activity and selectivity for the oxidation of benzyl alcohol to benzaldehyde with 85% conversion and 97% selectivity using air (1 atm) at 85 °C after 14 h. The catalyst also showed good activity in the hydrogenation of the C C bond in alkenes to corresponding alkanes and also benzaldehyde to benzyl alcohol at room temperature using H2 (1 atm). Rigorous test results confirmed that Pd-nanoparticles supported on MIL-101 are responsible for the catalytic reactions occurred. Pd/MIL-101 was reusable several times without losing the structural integrity and initial activity, and demonstrated significantly higher catalytic activities than those by a commercial Pd catalyst supported on activated carbon. Copyright
Encapsulation of supported metal nanoparticles with an ultra-thin porous shell for size-selective reactions
Shang, Zeyu,Patel, Rajankumar L.,Evanko, Brian W.,Liang, Xinhua
, p. 10067 - 10069 (2013)
A novel nanostructured catalyst with an ultra-thin porous shell obtained from the thermal decomposition of an aluminium alkoxide film deposited by molecular layer deposition for size-selective reactions was developed. The molecular sieving capability of the porous metal oxide films was verified by examining the liquid-phase hydrogenation of n-hexene versus cis-cyclooctene. The Royal Society of Chemistry 2013.
A Facile and In-situ Methanol-mediated Fabrication of Low Pd Loading, High-efficiency and Size-selectivity Pd@ZIF-8 Hydrogenation Catalyst
Zhang, Fengwei,Liu, Mengmeng,Liu, Qiang,Li, Jingjing,Li, Boyang,Dong, Zhengping
, p. 2952 - 2957 (2021)
In-situ encapsulation of tiny and well-dispersed Pd nanoparticles (Pd NPs) in zeolitic imidazolate frameworks (ZIFs) was firstly achieved using a one-pot and facile methanol-mediated growth approach, in which methanol served as both solvent and a mild reductant. The microstructure, morphology, crystallinity, porosity as well as evolution process of the catalysts were determined by TEM, XRD, N2 adsorption and UV-vis spectra. Due to the complete encapsulation of such Pd NPs combined with ultrahigh surface area and uniform microporous structure of ZIF-8, the resulting Pd@ZIF-8-60 min nanocomposite exhibited more superior catalytic activity for olefins hydrogenation with TOF of 7436 h?1 and excellent size selectivity than previously reported catalysts. Furthermore, the catalyst displays excellent recyclability for 1-octene hydrogenation and without any loss of the Pd active species.
CNC-pincer iron complexes containing a bis(N-heterocyclic carbene)Amido ligand: Synthesis and application to catalytic hydrogenation of alkenes
Ito, Jun-ichi,Taniguchi, Wakano,Yamashita, Makoto
, (2020)
This work studied preparation and catalytic application of CNC-pincer Fe complexes containing a bis(NHC)amido ligand (NHC: N-heterocyclic carbene). Deprotonation of bis(3-isopropylimidazoliumyl)amine salt [(CNCiPr)H3]2+[I?]2 (1a) with lithium hexamethyldisilazide (LiHMDS) afforded the corresponding bis(NHC)amido-Li complex 2a. Treatment of in-situ generated 2a with FeI2(thf)2 gave a CNC-pincer Fe(II) iodide complex Fe(CNCiPr)I (3a) and a cationic homoleptic Fe(III) complex [Fe(CNCiPr)2]+I? (4a). Reaction of in-situ generated 2a with Fe[N(SiMe3)2]2 produced the corresponding amido complex Fe(CNCiPr)[N(SiMe3)2] (5a). Similarly, deprotonation of a less hindered methyl analogue [(CNCMe)H3]2+[I?]2 (1b) with LiHMDS followed by treatment of Fe[N(SiMe3)2]2 gave an amido complex Fe(CNCMe)[N(SiMe3)2] (5b). Molecular structures of 3a, 5a and 5b, which were confirmed by X-ray diffraction study, showed a distorted tetrahedral geometry. Complexes 3a and 5b were found to be active in hydrogenation of alkenes. Reaction mechanism was investigated by density functional theory (DFT) calculations.
Crabtree et al.
, p. 716 (1976)
Pt nanoclusters confined within metal-organic framework cavities for chemoselective cinnamaldehyde hydrogenation
Guo, Zhiyong,Xiao, Chaoxian,Maligal-Ganesh, Raghu V.,Zhou, Lin,Goh, Tian Wei,Li, Xinle,Tesfagaber, Daniel,Thiel, Andrew,Huang, Wenyu
, p. 1340 - 1348 (2014)
A highly selective and robust catalyst based on Pt nanoclusters (NCs) confined inside the cavities of an amino-functionalized Zr-terephthalate metal-organic framework (MOF), UiO-66-NH2 was developed. The Pt NCs are monodisperse and confined in the cavities of UiO-66-NH2 even at 10.7 wt % Pt loading. This confinement was further confirmed by comparing the catalytic performance of Pt NCs confined inside and supported on the external surface of the MOF in the hydrogenation of ethylene, 1-hexene, and 1,3-cyclooctadiene. The benefit of confining Pt NCs inside UiO-66-NH2 was also demonstrated by evaluating their performance in the chemoselective hydrogenation of cinnamaldehyde. We found that both high selectivity to cinnamyl alcohol and high conversion of cinnamaldehyde can be achieved using the MOF-confined Pt nanocluster catalyst, while we could not achieve high cinnamyl alcohol selectivity on Pt NCs supported on the external surface of the MOF. The catalyst can be recycled ten times without any loss in its activity and selectivity. To confirm the stability of the recycled catalysts, we conducted kinetic studies for the first 20 h of reaction during four recycle runs on the catalyst. Both the conversion and selectivity are almost overlapping for the four runs, which indicates the catalyst is very stable under the employed reaction conditions.
Double addition of H2 to transition metal-borane complexes: A 'hydride shuttle' process between boron and transition metal centres
Tsoureas, Nikolaos,Kuo, Yu-Ying,Haddow, Mairi F.,Owen, Gareth R.
, p. 484 - 486 (2011)
The addition of H2 across a transition metal-borane bond is reported for the first time providing a mechanism for recharging borane functional groups to borohydride.
Yolk-shell nanocrystal@ZIF-8 nanostructures for gas-phase heterogeneous catalysis with selectivity control
Kuo, Chun-Hong,Tang, Yang,Chou, Lien-Yang,Sneed, Brian T.,Brodsky, Casey N.,Zhao, Zipeng,Tsung, Chia-Kuang
, p. 14345 - 14348 (2012)
A general synthetic strategy for yolk-shell nanocrystal@ZIF-8 nanostructures has been developed. The yolk-shell nanostructures possess the functions of nanoparticle cores, microporous shells, and a cavity in between, which offer great potential in heterogeneous catalysis. The synthetic strategy involved first coating the nanocrystal cores with a layer of Cu2O as the sacrificial template and then a layer of polycrystalline ZIF-8. The clean Cu2O surface assists in the formation of the ZIF-8 coating layer and is etched off spontaneously and simultaneously during this process. The yolk-shell nanostructures were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and nitrogen adsorption. To study the catalytic behavior, hydrogenations of ethylene, cyclohexene, and cyclooctene as model reactions were carried out over the Pd@ZIF-8 catalysts. The microporous ZIF-8 shell provides excellent molecular-size selectivity. The results show high activity for the ethylene and cyclohexene hydrogenations but not in the cyclooctene hydrogenation. Different activation energies for cyclohexene hydrogenation were obtained for nanostructures with and without the cavity in between the core and the shell. This demonstrates the importance of controlling the cavity because of its influence on the catalysis.
Inverse Isotope Effects in Single-Crystal to Single-Crystal Reactivity and the Isolation of a Rhodium Cyclooctane σ-Alkane Complex
Doyle, Laurence R.,Furfari, Samantha K.,Galpin, Martin R.,Hicks, Scott A.,Lloyd-Jones, Guy C.,MacGregor, Stuart A.,Martínez-Martínez, Antonio J.,Tegner, Bengt E.,Weller, Andrew S.,Whitwood, Adrian C.
supporting information, p. 284 - 292 (2022/02/10)
The sequential solid/gas single-crystal to single-crystal reaction of [Rh(Cy2P(CH2)3PCy2)(COD)][BArF4] (COD = cyclooctadiene) with H2 or D2 was followed in situ by solid-state 31P{1H} NMR spectroscopy (SSNMR) and ex situ by solution quenching and GC-MS. This was quantified using a two-step Johnson-Mehl-Avrami-Kologoromov (JMAK) model that revealed an inverse isotope effect for the second addition of H2, that forms a σ-alkane complex [Rh(Cy2P(CH2)3PCy2)(COA)][BArF4]. Using D2, a temporal window is determined in which a structural solution for this σ-alkane complex is possible, which reveals an η2,η2-binding mode to the Rh(I) center, as supported by periodic density functional theory (DFT) calculations. Extensive H/D exchange occurs during the addition of D2, as promoted by the solid-state microenvironment.
