- Synthetic, electrochemical, and structural studies on heterobimetallic crown thioether complexes with Group 10 metals: The crystal structures of [Pt(9S3)(dppf)](PF6)2·CH3NO2 and [Pd(9S3)(dppf)](PF6)2·CH3NO2
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The syntheses, electrochemistry, and crystal structures for two new Pt(II) and Pd(II) heteroleptic bimetallic complexes with the crown trithioether 1,4,7-trithiacyclononane (9S3) and the diphosphine ligand, 1,1′-bis(diphenylphosphino)ferrocene (dppf) are reported. Both complexes have the general formula [M(9S3)(dppf)](PF6)2 (M=Pt or Pd) and exhibit the anticipated structure forming a distorted cis square planar array of two sulfur atoms from the 9S3 and two phosphorus atoms. These are, to our knowledge, the first reported examples of dppf transition metal complexes involving a thioether as the ancillary ligand. The dppf ligand functions as a bidentate chelator to a single metal center, and the third 9S3 sulfur atom does interact with the metal ion from a greater distance (Pt-S=2.8167(8) ?; Pd-S=2.7916(5) ?) to yield an elongated square pyramidal geometry. The two structures are isomorphous with very similar bond distances and angles. The values for the 31P-NMR chemical shifts (Pt=15.09 ppm, Pd=-0.47 ppm), the 195Pt-NMR chemical shift for the Pt(II) complex (-4353 ppm) and 1J(195Pt-31P) coupling constants (3511 Hz) are all consistent with a cis-MS2P2 square planar coordination sphere. The 9S3 ligand is fluxional in solution for both complexes. The electrochemistry of both complexes is dominated by a reversible Fe(II)/Fe(III) couple from the ferrocene moiety (E1/2=+721 mV for Pt(II), +732 mV for Pd(II), both versus Fc/Fc+).
- Grant, Gregory J.,Carter, Shawn M.,LeBron Russell,Poullaos, Ivan M.,VanDerveer, Donald G.
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- Oxidatively Induced Aryl-CF3 Coupling at Diphosphine Nickel Complexes
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This communication describes the synthesis of a series of diphosphine NiII(Ph)(CF3) complexes and studies of their reactivity toward oxidatively induced Ph-CF3 bond-forming reductive elimination. Treatment of these complexes with the one-electron outer-sphere oxidant ferrocenium hexafluorophosphate (FcPF6) affords benzotrifluoride, but the yield varies dramatically as a function of diphosphine ligand. Diphosphines with bite angles of less than 92° afforded 3. In contrast, those with bite angles between 95 and 102° formed PhCF3 in yields ranging from 62 to 77%.
- Bour, James R.,Roy, Pronay,Canty, Allan J.,Kampf, Jeff W.,Sanford, Melanie S.
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supporting information
p. 3 - 7
(2020/01/03)
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- Efficient catalytic transfer hydrogenation reactions of carbonyl compounds by Ni(II)-diphosphine complexes
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The catalytic transfer hydrogenation reactions of a series of aromatic and aliphatic carbonyl compounds were investigated using divalent Ni(II)-diphosphine complexes, [L2NiCl2] (where L2 = 1,1-bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,1-bis(diphenylphosphino)ferrocene (dppf), and N-butyl-N-(diphenylphosphino)-1,1-diphenylphosphinamine (dppba)). This is a single-step reaction in the presence of potassium hydroxide and isopropyl alcohol to afford the corresponding alcohols. This protocol tolerates other sensitive functional groups like olefinic double bonds and also achieves high chemoselectivity. All the reactions were monitored by GC and GC–MS. The plausible mechanism is also discussed. The method reported in the present article is simple, cost-effective, and provides excellent conversions. Nickel-diphosphine complexes appear as a potential alternative to expensive transition metal complexes.
- Venkatesh, Sadhana,Panicker, Rakesh R.,Lenin Kumar, Verdhi,Pavankumar,Viswanath, Nukala,Singh, Shangrila,Desikan, Rajagopal,Sivaramakrishna, Akella
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p. 2963 - 2977
(2020/11/03)
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- METHOD FOR PREPARATION OF FLUORO ALKYLATED COMPOUNDS BY HOMOGENEOUS NI CATALYSIS
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The invention discloses a method for the preparation of fluoro alkylated compounds by homogeneous Ni catalyzed fluoro alkylation with fluoro alkyl halides in the presence of a base.
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Page/Page column 16-17
(2020/09/08)
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- METHOD FOR PREPARATION OF FLUORO ALKYLATED 1,4-DIOXENE BY HOMOGENEOUS NI CATALYSIS
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The invention discloses a method for the preparation of fluoro alkylated 1,4-dioxene by homogene- ous Ni catalyzed fluoro alkylation with fluoro alkyl halides of 1,4-dioxane in the presence of a base.
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Page/Page column 8; 9
(2020/09/08)
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- Selective nickel-catalyzed fluoroalkylations of olefins
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Mild and selective nickel-catalyzed trifluoromethylation and perfluoroalkylation reactions of alkenes were developed to provide fluorinated olefins, including natural products, pharmaceuticals, and variety of synthetic building blocks in good to excellent
- Zhang, Shaoke,Weniger, Florian,Ye, Fei,Rabeah, Jabor,Ellinger, Stefan,Zaragoza, Florencio,Taeschler, Christoph,Neumann, Helfried,Brückner, Angelika,Beller, Matthias
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supporting information
p. 15157 - 15160
(2020/12/21)
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- A general and practical Ni-catalyzed C-H perfluoroalkylation of (hetero)arenes
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A direct perfluoroalkylation of (hetero)arenes using the air- and moisture-stable complex (dppf)Ni(o-tol)Cl was developed (23 examples). The novel procedure allows for the synthesis of various fluorinated products and tolerates sensitive functional groups including aldehydes, free amino groups and several heterocycles.
- Zhang, Shaoke,Rotta-Loria, Nicolas,Weniger, Florian,Rabeah, Jabor,Neumann, Helfried,Taeschler, Christoph,Beller, Matthias
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supporting information
p. 6723 - 6726
(2019/06/17)
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- General and Mild Nickel-Catalyzed Cyanation of Aryl/Heteroaryl Chlorides with Zn(CN)2: Key Roles of DMAP
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A new and general nickel-catalyzed cyanation of hetero(aryl) chlorides using less toxic Zn(CN)2 as the cyanide source has been developed. The reaction relies on the use of inexpensive NiCl2·6H2O/dppf/Zn as the catalytic system and DMAP as the additive, allowing the cyanation to occur under mild reaction conditions (50-80 °C) with wide functional group tolerance. DMAP was found to be crucial for successful transformation, and the reaction likely proceeds via a Ni(0)/Ni(II) catalysis based on mechanistic studies. The method was also successfully extended to aryl bromides and aryl iodides.
- Zhang, Xingjie,Xia, Aiyou,Chen, Haoyi,Liu, Yuanhong
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supporting information
p. 2118 - 2121
(2017/04/27)
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- Comparison of dppf-Supported Nickel Precatalysts for the Suzuki-Miyaura Reaction: The Observation and Activity of Nickel(I)
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Ni-based precatalysts for the Suzuki-Miyaura reaction have potential chemical and economic advantages compared to commonly used Pd systems. Here, we compare Ni precatalysts for the Suzuki-Miyaura reaction supported by the dppf ligand in 3 oxidation states, 0, I and II. Surprisingly, at 80 °C they give similar catalytic activity, with all systems generating significant amounts of NiI during the reaction. At room temperature a readily accessible bench-stable NiII precatalyst is highly active and can couple synthetically important heterocyclic substrates. Our work conclusively establishes that NiI species are relevant in reactions typically proposed to involve exclusively Ni0 and NiII complexes.
- Guard, Louise M.,Mohadjer Beromi, Megan,Brudvig, Gary W.,Hazari, Nilay,Vinyard, David J.
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supporting information
p. 13352 - 13356
(2015/11/09)
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- A nickel phosphine complex as a fast and efficient hydrogen production catalyst
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(Chemical Equation Presented) Here we report the electrocatalytic reduction of protons to hydrogen by a novel S2P2 coordinated nickel complex, [Ni(bdt)(dppf)] (bdt = 1,2-benzenedithiolate, dppf = 1,1′-bis(diphenylphosphino)ferrocene). The catalysis is fast and effi cient with a turnover frequency of 1240 s-1 and an overpotential of only 265 mV for half activity at low acid concentrations. Furthermore, catalysis is possible using a weak acid, and the complex is stable for at least 4 h in acidic solution. Calculations of the system carried out at the density functional level of theory (DFT) are consistent with a mechanism for catalysis in which both protonations take place at the nickel center.
- Gan, Lu,Groy, Thomas L.,Tarakeshwar, Pilarisetty,Mazinani, Shobeir K. S.,Shearer, Jason,Mujica, Vladimiro,Jones, Anne K.
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p. 1109 - 1115
(2015/02/05)
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- NICKEL PRE-CATALYSTS AND RELATED COMPOSITIONS AND METHODS
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Described herein are nickel pre-catalysts and related compositions and methods. The nickel pre-catalysts may be activated to form catalysts which may be utilized in organic reactions.
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Page/Page column 40
(2015/05/26)
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- A broadly applicable strategy for entry into homogeneous nickel(0) catalysts from air-stable nickel(II) complexes
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A series of air-stable nickel complexes of the form L2Ni(aryl) X (L = monodentate phosphine, X = Cl, Br) and LNi(aryl)X (L = bis-phosphine) have been synthesized and are presented as a library of precatalysts suitable for a wide variety of nickel-catalyzed transformations. These complexes are easily synthesized from low-cost NiCl2·6H2O or NiBr 2·3H2O and the desired ligand followed by addition of 1 equiv of Grignard reagent. A selection of these complexes were characterized by single-crystal X-ray diffraction, and an analysis of their structural features is provided. A case study of their use as precatalysts for the nickel-catalyzed carbonyl-ene reaction is presented, showing superior reactivity in comparison to reactions using Ni(cod)2. Furthermore, as the precatalysts are all stable to air, no glovebox or inert-atmosphere techniques are required to make use of these complexes for nickel-catalyzed reactions.
- Standley, Eric A.,Smith, Stacey J.,Mueller, Peter,Jamison, Timothy F.
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supporting information
p. 2012 - 2018
(2014/05/20)
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- Process design and scale-up of the synthesis of 2,2′:5′,2′-terthienyl
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The objective of this study was the design of a scaleable process for the synthesis of 3-4 mol of α-terthienyl from 2,5-dibromothiophene and thienylmagnesium bromide in a 10-L stirred tank reactor. In THF the Grignard reagent, thienylmagnesium bromide, was readily formed from 2-bromothiophene and magnesium. To avoid crystallization the maximal concentration was limited to 1.4 M. Furthermore, the novel combination of THF and NiCl2[bis(diphenylphosphino)benzene] allows for fast double coupling of the Grignard reagent with 2,5-dibromothiophene. The concentration of catalyst could be limited to 0.5 mol % based on the amount of 2,5-dibromothiophene. An adapted workup procedure was developed, in which n-octane was used to separate the magnesium salts from the desired product. The reaction was performed in a (semi)batch-wise operated reactor. A global model for the coupling step proved to predict the results at 0.1-, 1-, and 10-L scales very accurately. The heat of reaction evolved in the coupling step was valorized and could be handled easily. Mixing of the feed stream and the reactor content proved to be another important factor in the scaling-up of the α-terthienyl synthesis.
- Smeets,Meijer,Meuldijk,Vekemans,Hulshof
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