- Safe preparation and purification of sodium tetrakis[(3,5-trifluoromethyl) phenyl]borate (NaBArF24): Reliable and sensitive analysis of water in solutions of fluorinated tetraarylborates
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A safe, convenient preparation of the reagent sodium tetrakis[(3,5- trifluoromethyl)phenyl]borate (NaBArF24) has been devised by utilizing a magnesium-bromine exchange reaction in the absence of metallic magnesium. Purified material was then rigorously dried over P2O 5 (NaBArF24 with 2O by mass) or recrystallized as a hydrate (NaBArF24·(2.6 ± 0.1)H 2O). Accurate analysis of the water content of these samples by 1H NMR was accomplished by using dimethylzirconocene (Cp 2Zr(CH3)2).
- Yakelis, Neal A.,Bergman, Robert G.
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- [(3,5-(CF3)2C6H3) 4B]-[H(OEt2)2]+: A convenient reagent for generation and stabilization of cationic, highly electrophilic organometallic complexes
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A convenient synthesis of the easily handled, crystalline oxonium acid [(3,5-(CF3)2C6H3)4B] -[H(OEt2)2]+ (1) is described. The utility of this reagent for generation and stabilization of highly electrophilic cationic transition-metal complexes through protonation reactions is illustrated by the preparation of stable, ether-free salts of [C5Me5(P(OMe)3)CoCH2CH 2(μ-H)]+[(3,5-(CF3)2C 6H3)4B]- from C5Me5(P(OMe)3)Co(C2H4). The incorporation of the noncoordinating counterion [(3,5-(CF3)2C6H3)4B] - in organometallic salts has several advantages relative to [BF4]- and [PF6]-, including high stability and solubility in relatively nonpolar organic solvents.
- Brookhart,Grant,Volpe Jr.
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Read Online
- Rip It off: Nitro to Nitroso Reduction by Iron Half-Sandwich Complexes
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Activation of [FeCl(dppe)Cp] (1) by chloride abstraction with Na[BArX4] (X = F, [B(3,5-(CF3)2-C6H3)4]; X = Cl, [B(3,5-Cl2-C6H3)4]) permits reactions with a range of nitro aromatics, RC6H4NO2 (R = halogen, Me, OMe, NO2 or NMe2), to give the cationic iron nitroso complexes [Fe{N(O)-C6H4R}(dppe)Cp][BArX4]) ([3][BArX4]). Similar reactions of 1 and Na[BArX4] with [Fe(NCC6H4NO2)(dppe)Cp][BArX4] gave bimetallic [{Fe(dppe)Cp}2{μ-NCC6H4N(O)}][BArF4]2. However, reactions of 1 and Na[BArX4] with 4-nitrophenol gave the first example of the bench-stable iron half-sandwich phenolate complex [Fe(OC6H4NO2)(dppe)Cp]+ rather than NO2 activation. The formation of complexes [3]+ likely proceeds via the unusual blue bimetallic species [{Fe(dppe)Cp}2{μ,κ2O,O′-O2NAr}]2+. This compound undergoes N-O bond cleavage, resulting in [3]+ and a FeIV=O species, which reacts via an internal C-H activation of the dppe ligand to give [FeIII(κ3O,P,P′-P(2-O-C6H4)(Ph)-C2H4-PPh2)Cp]+. Complexes [3]+ are stable under ambient conditions, are readily purified by column chromatography and can be isolated in up to 50% yield, considering that 0.5 equiv of 1 is required as the oxygen acceptor.
- Korb, Marcus,Hosseini Ghazvini, Seyed Mohammad Bagher,Moggach, Stephen A.,Meunier, Jean-Fran?ois,Bousseksou, Azzedine,Low, Paul J.
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supporting information
p. 4986 - 4995
(2021/04/06)
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- N-Heterocyclic Iod(az)olium Salts – Potent Halogen-Bond Donors in Organocatalysis
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This article describes the application of N-heterocyclic iod(az)olium salts (NHISs) as highly reactive organocatalysts. A variety of mono- and dicationic NHISs are described and utilized as potent XB-donors in halogen-bond catalysis. They were benchmarked in seven diverse test reactions in which the activation of carbon- and metal-chloride bonds as well as carbonyl and nitro groups was achieved. N-methylated dicationic NHISs rendered the highest reactivity in all investigated catalytic applications with reactivities even higher than all previously described monodentate XB-donors based on iodine(I) and (III) and the strong Lewis acid BF3.
- Boelke, Andreas,Kuczmera, Thomas J.,Lork, Enno,Nachtsheim, Boris J.
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supporting information
p. 13128 - 13134
(2021/08/09)
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- Gold-Catalyzed Carbazolation Reactions of Alkynes
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Herein, we report on a Au(I)-catalyzed reaction of alkynes with carbazoles that enables a one-step synthesis of vinyl carbazoles that are important molecules for applications as photoluminescent materials. This reaction proceeds under mild conditions at r
- He, Feifei,Jana, Sripati,Koenigs, Rene M.
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supporting information
(2020/07/03)
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- Solvent-free anhydrous Li+, Na+ and K+ salts of [B(3,5-(CF3)2C6H3)4]-, [BArF4]-. Improved synthesis and solid-state structures
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A modified, convenient, preparation of solvent-free, anhydrous, Li+, Na+ and K+ salts of the ubiquitous [BArF4]- anion is reported, that involves a simple additional recrystallisation step.
- Martínez-Martínez, Antonio J.,Weller, Andrew S.
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supporting information
p. 3551 - 3554
(2019/04/03)
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- Halo-1,2,3-triazolium salts as halogen bond donors for the activation of imines in dihydropyridinone synthesis
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In the past decade halogen bond (XB) catalysis has gained considerable attention. Halo-triazoles are known XB donors, yet few examples detail their use as catalysts. As a continuation of our previous work the catalytic properties of substituted enantiomerically pure halo-triazolium salts were explored in the reaction between an imine and Danishefsky's diene leading to the formation of dihydropyridinone. The catalytic activity of the XB donors was highly dependent on the choice of the halogen atom and on the counterion. Also, it was found that impurities in the diene affected the rate of the reaction.
- Kaasik, Mikk,Metsala, Andrus,Kaabel, Sandra,Kriis, Kadri,J?rving, Ivar,Kanger, Tonis
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p. 4295 - 4303
(2019/03/29)
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- Annelated Cyclobutanes by Fe-Catalyzed Cycloisomerization of Enyne Acetates
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Cationic Fe complexes of the general type [(Ph3P)2Fe(CO)(NO)]X (X=BF4, BArF4) catalyze the redox-neutral cycloisomerization of 1,6- and 1,7-enyneacetates to afford bicyclic cyclobutanes under mild conditions in good yields and diastereoselectivities.
- Kramm, Frederik,Teske, Johannes,Ullwer, Franziska,Frey, Wolfgang,Plietker, Bernd
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supporting information
p. 13335 - 13338
(2018/09/25)
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- Adaptive Behavior of Dynamic Orthoester Cryptands
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The integration of dynamic covalent bonds into macrocycles has been a tremendously successful strategy for investigating noncovalent interactions and identifying effective host–guest pairs. While numerous studies have focused on the dynamic responses of macrocycles and larger cages to various guests, the corresponding constitutionally dynamic chemistry of cryptands remains unexplored. Reported here is that cryptands based on orthoester bridgeheads offer an elegant entry to experiments in which a metal ion selects its preferred host from a dynamic mixture of competing subcomponents. In such dynamic mixtures, the alkali metal ions Li+, Na+, K+, Rb+, and Cs+exhibit pronounced preferences for the formation of cryptands of certain sizes and donor numbers, and the selection is rationalized by DFT calculations. Reported is also the first self-assembly of a chiral orthoester cryptate and a preliminary study on the use of stereoisomers as subcomponents.
- Shyshov, Oleksandr,Brachvogel, René-Chris,Bachmann, Tobias,Srikantharajah, Rubitha,Segets, Doris,Hampel, Frank,Puchta, Ralph,von Delius, Max
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supporting information
p. 776 - 781
(2017/01/14)
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- Tunable aryl alkyl ionic liquids with weakly coordinating bulky borate anion
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A series of 1-aryl 3-alkyl imidazolium tetrakis[bis-3,5(trifluoromethyl)phenyl]borate [BArF3,5] ionic liquids were synthesized and characterized. Increasing the alkyl chain length leads to lower melting points even resulting in room temperature
- Kaliner, Maria,Strassner, Thomas
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supporting information
p. 3453 - 3456
(2016/07/18)
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- Iridium(I) N-Heterocyclic Carbene (NHC)/Phosphine Catalysts for Mild and Chemoselective Hydrogenation Processes
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The directed chemoselective hydrogenation of olefins has been established by using iridium(I) catalysts, which feature a tuned NHC/phosphine ligand combination. This selective reduction process has been demonstrated in a wide array of solvents, including more environmentally acceptable media, also allowing further refinement of hydrogenation selectivity. The directed, chemoselective hydrogenation of olefins has been established by using iridium(I) catalysts, which feature a tuned NHC/phosphine ligand combination. This selective reduction process has been demonstrated in a wide array of solvents, including more environmentally acceptable media, also allowing further refinement of hydrogenation selectivity.
- Kerr, William J.,Mudd, Richard J.,Brown, Jack A.
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supporting information
p. 4738 - 4742
(2016/04/05)
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- Addition of Small Electrophiles to N-Heterocyclic-Carbene-Stabilized Disilicon(0): A Revisit of the Isolobal Concept in Low-Valent Silicon Chemistry
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Protonation and alkylation of (Idipp)S=Si(Idipp) (1) afforded the mixed-valent disilicon(I)-borates [(Idipp)(R)SiII=Si0(Idipp)][B(ArF)4] (1R[B(ArF)4]; R = H, Me, Et; ArF = C6H3-3,5-(CF3)2; Idipp = C[N(C6H3-2,6-iPr2)CH]2) as red to orange colored, highly air-sensitive solids, which were characterized by single-crystal X-ray diffraction, IR spectroscopy and multinuclear NMR spectroscopy. Dynamic NMR studies in solution revealed a degenerate isomerization (topomerization) of the "σ-bonded" tautomers of 1H[B(ArF)4], which proceeds according to quantum chemical calculations via a NHC-stabilized (NHC = N-heterocyclic carbene) disilahydronium ion ("π-bonded" isomer) and is reminiscent of the degenerate rearrangement of carbenium ions formed upon protonation of olefins. The topomerization of 1H[B(ArF)4] provides the first example of a reversible 1,2-H migration along a Si=Si bond observed in a molecular system. In contrast, 1Me[B(ArF)4] adopts a "rigid" structure in solution due to the higher energy required for the interconversion of the "σ-bonded" isomer into a putative NHC-stabilized disilamethonium ion. Addition of alkali metal borates to 1 afforded the alkali metal disilicon(0) borates 1M[BAr4] (M = Li, Ar = C6F5; M = Na, Ar = ArF) as brown, air-sensitive solids. Single-crystal X-ray diffraction analyses and NMR spectroscopic studies of 1M[BAr4] suggest in concert with quantum chemical calculations that encapsulation of the alkali metal cations in the cavity of 1 predominantly occurs via electrostatic cation-π interactions with the Si=Si π-bond and the peripheral NHC aryl rings. Displacement of the [Si(NHC)] fragments by the isolobal fragments [PR] and [SiR]- interrelates the cations [(NHC)(R)Si=Si(NHC)]+ to a series of familiar, multiply bonded Si and P compounds as verified by analyses of their electronic structures.
- Arz, Marius I.,Stra?mann, Martin,Gei?, Daniel,Schnakenburg, Gregor,Filippou, Alexander C.
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p. 4589 - 4600
(2016/05/09)
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- Electronic effects of ligand substitution on spin crossover in a series of diiminoquinonoid-bridged feii2 complexes
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A series of four isostructural FeII2 complexes, [(TPyA)2Fe2(XL)]2+ (TPyA = tris(2-pyridylmethyl)amine; XL2- = doubly deprotonated form of 3,6-disubstituted-2,5-dianili
- Park, Jesse G.,Jeon, Ie-Rang,Harris, T. David
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p. 359 - 369
(2015/05/26)
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- Electronic effects of ligand substitution on spin crossover in a series of diiminoquinonoid-bridged FeII2 complexes
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A series of four isostructural FeII2 complexes, [(TPyA)2Fe2(XL)]2+ (TPyA = tris(2-pyridylmethyl)amine; XL2-= doubly deprotonated form of 3,6-disubstituted-2,5-dianilin
- Park, Jesse G.,Jeon, Ie-Rang,Harris, T. David
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p. 359 - 369
(2017/01/17)
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- Quantitative photochemical formation of [Ru(tpy)(bpy)H]+
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Quantitative photochemical production of [Ru(tpy)(bpy)H]+ (Ru-H+) was achieved by irradiation of [Ru(tpy)(bpy)(DMF)] 2+ (Ru-DMF2-; DMF = N,N-dimethylformamide) in a tetrahydroturan (THF) solution containing exce
- Matsubara, Yasuo,Konno, Hideo,Kobayashi, Atsuo,Ishitani, Osamu
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p. 10138 - 10145
(2010/04/01)
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- Method for enantioselective hydrogenation of chromenes
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A method for preparing an enantiomeric chromane, by asymmetrically hydrogenating a chromene compound in the presence of an Ir catalyst having a chiral ligand. The method includes the enantioselective preparation of enantiomeric equol. A preferred Ir catalyst has a chiral phosphineoxazoline ligand. Enantiomeric chromanes of high stereoselective purity can be obtained.
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Page/Page column 7
(2008/06/13)
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- Solution structure investigation of Ru(II) complex ion pairs: Quantitative NOE measurements and determination of average interionic distances
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The structure of the Ru(II) ion pairs trans-[Ru(COMe){(pz2)CH2}(CO)(PMe3) 2]X (X- = BPh4-, 1a; BPh3Me-, 1b; BPh3(n-Bu)-, 1c; BPh3
- Zuccaccia,Bellachioma,Cardaci,Macchioni
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p. 11020 - 11028
(2007/10/03)
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