7688-21-3Relevant articles and documents
Highly cis-selective and lead-free hydrogenation of 2-hexyne by a supported Pd catalyst with an ionic-liquid layer
Schwab, Frederick,Weidler, Natascha,Lucas, Martin,Claus, Peter
, p. 10406 - 10408 (2014)
A simple Pd/SiO2 catalyst which was modified with the ionic liquid [BMPL][DCA] gave an excellent yield of 88% towards cis-2-hexene in the stereoselective hydrogenation of 2-hexyne. The catalyst outperforms, even at full conversion, the commonly used lead-poisoned, toxic Lindlar catalyst and supported colloidal-based Pd as well. This journal is the Partner Organisations 2014.
Stereoselective hydrogenation of 2-hexyne on Cu/γ-Al2O3 catalysts
Pak, A. M.,Kartonozhkina, O. I.,Izdebskaya, G. T.,Ermolaev, V. N.,Korolev, A. V.
, p. 1257 - 1259 (1993)
The stereoselective hydrogenation of 2-hexyne in ethanol on Cu/γ-Al2O3 catalysts (1-40percent Cu) at 4-10 atm and 80-120 deg C has been studied.The reaction affords cis-2-hexene as the only reaction product in 100percent yield at 20percent Cu, hydrogenation proceeds in parallel with adsorption of H2 by the catalyst.
Geometrically Constrained Cationic Low-Coordinate Tetrylenes: Highly Lewis Acidic σ-Donor Ligands in Catalytic Systems
Keil, Philip M.,Hadlington, Terrance J.
supporting information, (2022/01/13)
A novel non-innocent ligand class, namely cationic single-centre ambiphiles, is reported in the phosphine-functionalised cationic tetrylene Ni0 complexes, [PhRDippENi(PPh3)3]+ (4 a/b (Ge) and 5 (Sn); PhRDipp={[Ph2PCH2SiR2](Dipp)N}?; R=Ph, iPr; Dipp=2,6-iPr2C6H3). The inherent electronic nature of low-coordinate tetryliumylidenes, combined with the geometrically constrained [N?E?Ni] bending angle enforced by the chelating phosphine arm in these complexes, leads to strongly electrophilic EII centres which readily bind nucleophiles, reversibly in the case of NH3. Further, the GeII centre in 4 a/b readily abstracts the fluoride ion from [SbF6]? to form the fluoro-germylene complex PhRDippGe(F)Ni(PPh3)3 9, despite this GeII centre simultaneously being a σ-donating ligand towards Ni0. Alongside the observed catalytic ability of 4 and 5 in the hydrosilylation of alkynes and alkenes, this forms an exciting introduction to a multi-talented ligand class in cationic single-centre ambiphiles.
Allylnickel(II) complexes of bulky 5-substituted-2-iminopyrrolyl ligands
Cruz, Tiago F. C.,Gomes, Pedro T.,Lopes, Patrícia S.
, (2021/08/05)
The optimized reaction between [Ni(COD)2] (COD = 1,5-cyclooctadiene) and ligand precursor 5-(2,4,6-triisopropylphenyl)-2-[N-(2,6-diisopropylphenyl)-formimino]-1H-pyrrole yielded the η3-cyclooctenyl-Ni(II) complex [Ni{κ2N,N’-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H) = N(2,6-iPr2C6H3)}(η3-C8H13)] 1. Subsequently, the η3-allyl complexes [Ni{κ2N,N’-5-R-NC4H2-2-C(H)=N(2,6-iPr2C6H3)}(η3-C3H5)] (R = 3,5-(CF3)2C6H3 (2a), 2,6-Me2C6H3 (2b), 2,4,6-iPr3C6H2 (2c) and CPh3 (2d)) were prepared in good yields via metathesis of [Ni(η3-C3H5)(μ-Br)]2 with the respective potassium 5-R-2-[N-(2,6-diisopropylphenyl)formimino]pyrrolyl salt (KLa-d). Complexes 1 and 2a-d were characterized by NMR spectroscopy, elemental analysis and complex 2d further analyzed by single crystal X-ray diffraction. Addition of excess pyridine to solutions of complexes 2a-d led to the observation of a fluxional process that, according to VT-NMR experiments, corresponds to a pyridine-assisted cis–trans isomerization process occurring in these complexes, via a η3-η1-η3 haptotropic shift of the allyl ligand, with ΔG? values in range of 9.5–17.3 kcal mol?1. Additionally, complexes 2a-d, when activated by B(C6F5)3, slowly catalyzed the isomerization of hex-1-ene to mixtures of internal olefins.
Designing and synthesis of phosphine derivatives of Ru3(CO)12 – Studies on catalytic isomerization of 1-alkenes
Pandya, Chayan,Panicker, Rakesh R.,Senjaliya, Parth,Hareendran, M.K. Hima,Anju,Sarkar, Sibasis,Bhat, Haamid,Jha, Prakash C.,Rao, Koya Prabhakara,Smith, Gregory S.,Sivaramakrishna, Akella
, (2021/01/12)
A comparative investigation on the isomerization reactions of 1-alkenes to their corresponding 2-alkenes catalyzed Ru3(CO)12 (1), Ru3(CO)9(PEt3)3 (2) and Ru3(CO)10(dppe) (3), (where dppe = 1,2-bis(diphenylphosphino)ethane) is described. Both the complexes of types 2 and 3 were characterized by all analytical and spectroscopic data. The molecular structure of 2 was confirmed by single-crystal X-ray analysis. It is observed that the nature of phosphine ligands plays an important role in the isomerization of 1-alkenes. When the chelated diphosphine is used, the internal isomerization reaction by [Ru3(CO)10(dppe)] (3) is completed relatively in less time compared to other derivatives. As per the DFT calculations, the observed reaction rate for the alkene isomerization may be explained based on the relative stability of 1, 2, and 3. The CO abstraction step is highly feasible in 3, the least stable among the three, thus the reaction occurs at the highest rate. Due to the increased relative stability from 2 to 1, the reaction requires more time at elevated temperatures and the rate decreases as a consequence.
Immobilized Platinum Hydride Species as Catalysts for Olefin Isomerizations and Enyne Cycloisomerizations
Bauer, Matthias,Cronin, Steve P.,Dyballa, Michael,Estes, Deven P.,Li, Zheng,Maier, Sarah,Nowakowski, Michal,Vu Dinh, Manh-Anh
supporting information, p. 1751 - 1757 (2021/06/28)
Platinum hydride species catalyze a number of interesting organic reactions. However, their reactions typically involve the use of high loadings of noble metal and are difficult to recycle, making them somewhat unsustainable. We have synthesized surface-immobilized Pt-H species via oxidative addition of surface OH groups to Pt(PtBu3)2 (1), a rarely used immobilization technique in surface organometallic chemistry. The hydride species thus made were characterized by infrared, magic-angle spinning nuclear magnetic resonance, and X-ray absorption spectroscopies and catalyzed both olefin isomerization and cycloisomerization of a 1,6 enyne (5) with a high selectivity and low Pt loading.
Comparative Study of Homogeneous and Silica Immobilized N^N and N^O Palladium(II) Complexes as Catalysts for Hydrogenation of Alkenes, Alkynes and Functionalized Benzenes
Akiri, Saphan O.,Ngcobo, Nondumiso L.,Ojwach, Stephen O.
, p. 2850 - 2862 (2020/03/30)
Abstract: This work reports the use of homogeneous and silica immobilized palladium(II) complexes of ligands (2-phenyl-2-((3(triethoxysilyl)propyl)imino)ethanol) (L1), (4-methyl-2-((3(triethoxysilyl)propyl)imino)methyl)phenol) (L2), [L1-MCM-41] (L1im), and [L2-MCM-41] (L2im) as catalysts in molecular hydrogenation of alkenes, alkynes and functionalized benzenes. The homogeneous complexes [Pd(L1)2] (Pd1), [Pd(L2)2] (Pd2), [Pd(L1)(Cl2)] (Pd3),?and [Pd(L2)(Cl2)] (Pd4), and their respective silica immobilized?complexes [Pd(L1)2]-MCM-41] (Pd1im), [Pd(L2)2)-MCM-4] (Pd2im), [Pd (L1)(Cl2)-MCM-41] (Pd3im) and [Pd(L2)(Cl2)]-MCM-41] (Pd4im) formed active catalysts in?the molecular hydrogenation of these substrates. The catalytic activities and product distribution in these reactions were largely dictated by the nature of the substrate. The kinetic studies revealed a pseudo-first order dependence on styrene substrate for both the homogeneous and immobilized catalysts. Significantly, the selectivity of both homogeneous and immobilized catalysts were comparable in the hydrogenation of both?alkynes and multi-functionalized benzenes. The supported catalysts could be recycled up to four times with minimum loss of catalytic activity and showed absence of any leaching from hot filtration experiments. Kinetics and poisoning studies established that complexes Pd1–Pd4 were largely homogeneous in nature, while the immobilized complexes Pd1im–Pd4im formed Pd(0) nanoparticles as the main active species. Graphic Abstract: [Figure not available: see fulltext.].
Bis(phosphine)hydridorhodacarborane Derivatives of 1,1′-Bis(ortho-carborane) and Their Catalysis of Alkene Isomerization and the Hydrosilylation of Acetophenone
Chan, Antony P. Y.,Parkinson, John A.,Rosair, Georgina M.,Welch, Alan J.
supporting information, (2020/02/04)
Deprotonation of [7-(1′-closo-1′,2′-C2B10H11)-nido-7,8-C2B9H11]- and reaction with [Rh(PPh3)3Cl] results in isomerization of the metalated cage and the formation of [8-(1′-closo-1′,2′-C2B10H11)-2-H-2,2-(PPh3)2-closo-2,1,8-RhC2B9H10] (1). Similarly, deprotonation/metalation of [8′-(7-nido-7,8-C2B9H11)-2′-(p-cymene)-closo-2′,1′,8′-RuC2B9H10]- and [8′-(7-nido-7,8-C2B9H11)-2′-Cp*-closo-2′,1′,8′-CoC2B9H10]- affords [8-{8′-2′-(p-cymene)-closo-2′,1′,8′-RuC2B9H10}-2-H-2,2-(PPh3)2-closo-2,1,8-RhC2B9H10] (2) and [8-(8′-2′-Cp*-closo-2′,1′,8′-CoC2B9H10)-2-H-2,2-(PPh3)2-closo-2,1,8-RhC2B9H10] (3), respectively, as diastereoisomeric mixtures. The performances of compounds 1-3 as catalysts in the isomerization of 1-hexene and in the hydrosilylation of acetophenone are compared with those of the known single-cage species [3-H-3,3-(PPh3)2-closo-3,1,2-RhC2B9H11] (I) and [2-H-2,2-(PPh3)2-closo-2,1,12-RhC2B9H11] (V), the last two compounds also being the subjects of 103Rh NMR spectroscopic studies, the first such investigations of rhodacarboranes. In alkene isomerization all the 2,1,8-or 2,1,12-RhC2B9 species (1-3, V) outperform the 3,1,2-RhC2B9 compound I, while for hydrosilylation the single-cage compounds I and V are better catalysts than the double-cage species 1-3.
Two-State Reactivity in Iron-Catalyzed Alkene Isomerization Confers σ-Base Resistance
Lutz, Sean A.,Hickey, Anne K.,Gao, Yafei,Chen, Chun-Hsing,Smith, Jeremy M.
supporting information, p. 15527 - 15535 (2020/10/20)
A low-coordinate, high spin (S = 3/2) organometallic iron(I) complex is a catalyst for the isomerization of alkenes. A combination of experimental and computational mechanistic studies supports a mechanism in which alkene isomerization occurs by the allyl mechanism. Importantly, while substrate binding occurs on the S = 3/2 surface, oxidative addition to an η1-allyl intermediate only occurs on the S = 1/2 surface. Since this spin state change is only possible when the alkene substrate is bound, the catalyst has high immunity to typical σ-base poisons due to the antibonding interactions of the high spin state.
Monohydride-Dichloro Rhodium(III) Complexes with Chiral Diphosphine Ligands as Catalysts for Asymmetric Hydrogenation of Olefinic Substrates
Higashida, Kosuke,Brüning, Fabian,Tsujimoto, Nagataka,Higashihara, Kenya,Nagae, Haruki,Togni, Antonio,Mashima, Kazushi
, p. 8749 - 8759 (2020/07/04)
We report full details of the synthesis and characterization of monohydride-dichloro rhodium(III) complexes bearing chiral diphosphine ligands, such as (S)-BINAP, (S)-DM-SEGPHOS, and (S)-DTBM-SEGPHOS, producing cationic triply chloride bridged dinuclear rhodium(III) complexes (1 a: (S)-BINAP; 1 b: (S)-DM-SEGPHOS) and a neutral mononuclear monohydride-dichloro rhodium(III) complex (1 c: (S)-DTBM-SEGPHOS) in high yield and high purity. Their solid state structure and solution behavior were determined by crystallographic studies as well as full spectral data, including DOSY NMR spectroscopy. Among these three complexes, 1 c has a rigid pocket surrounded by two chloride atoms bound to the rhodium atom together with one tBu group of (S)-DTBM-SEGPHOS for fitting to simple olefins without any coordinating functional groups. Complex 1 c exhibited superior catalytic activity and enantioselectivity for asymmetric hydrogenation of exo-olefins and olefinic substrates. The catalytic activity of 1 c was compared with that of well-demonstrated dihydride species derived in situ from rhodium(I) precursors such as [Rh(cod)Cl]2 and [Rh(cod)2]+[BF4]? upon mixing with (S)-DTBM-SEGPHOS under dihydrogen.
