212619-93-7Relevant academic research and scientific papers
Aqua, alcohol, and acetonitrile adducts of tris(perfluorophenyl)borane: Evaluation of bronsted acidity and ligand lability with experimental and computational methods
Bergquist, Catherine,Bridgewater, Brian M.,Harlan, C. Jeff,Norton, Jack R.,Friesner, Richard A.,Parkin, Gerard
, p. 10581 - 10590 (2000)
Equilibrium studies have been performed to determine the Bronsted acidity of [(C6F5)3B (OH2)]· H2O, the aqua species that exists in acetonitrile solutions of B(C6F5)3 in the presence of water. NMR spectroscopic analysis of the deprotonation of [(C6F5)3B(OH2)]·H 2O with 2,6-But2C5H3N in acetonitrile allows a pK value of 8.6 to be determined for the equilibrium [(C6F5)3B(OH2)]·H 2O ? [(C6F5)3B(OH)]- + [H3O]+. On the basis of a calculated value for the hydrogen bond interaction in [(C6F5)3B(OH2)]·H 2O, the pKa for (C6F5)3B(OH2) is estimated to be 8.4 in acetonitrile. Such a value indicates that (C6F5)3B(OH2) must be regarded as a strong acid, with a strength comparable to that of HCl in acetonitrile. Dynamic NMR spectroscopic studies indicate that the aqua and acetonitrile ligands in (C6F5)3B(OH2) and (C6F5)3B(NCMe) are labile, with dissociation of H2O being substantially more facile than that of MeCN, by a factor of ca. 200 in rate constant at 300 K. Ab initio calculations were performed in the gas phase and with a dielectric solvent model to determine the strength of B-L bonds (L = H2O, ROH, MeCN) and hydrogen bonds involving B-OH2 and B-O(H)R derivatives.
Structures and Stability of Complexes of E(C6F5)3 (E = B, Al, Ga, In) with Acetonitrile
Shcherbina, Nadezhda A.,Pomogaeva, Anna V.,Lisovenko, Anna S.,Kazakov, Igor V.,Gugin, Nikita Yu.,Khoroshilova, Olesya V.,Kondrat'ev, Yuri V.,Timoshkin, Alexey Y.
supporting information, p. 873 - 881 (2020/05/05)
Complexes formed by interaction of E(C6F5)3 (E = B, Al, Ga, In) with excess of acetonitrile (AN) were structurally characterized. Quantum chemical computations indicate that for Al(C6F5)3 and In(C6F5)3 the formation of a complex of 1:2 composition is more advantageous than for B(C6F5)3 and Ga(C6F5)3, in line with experimental observations. Formation of the solvate [Al(C6F5)3·2AN]·AN is in agreement with predicted thermodynamic instability of [Al(C6F5)3·3AN]. Tensimetry study of B(C6F5)3·CH3CN reveals its stability in the solid state up to 197 °C. With the temperature increase, the complex undergoes irreversible thermal decomposition with pentafluorobenzene formation.
Photo Lewis acid generators: Photorelease of B(C6F5)3 and applications to catalysis
Khalimon, Andrey Y.,Shaw, Bryan K.,Marwitz, Adam J. V.,Piers, Warren E.,Blackwell, James M.,Parvez, Masood
, p. 18196 - 18206 (2015/10/28)
A series of molecules capable of releasing of the strong organometallic Lewis acid B(C6F5)3 upon exposure to 254 nm light have been developed. These photo Lewis acid generators (PhLAGs) can now serve as photoinitiators for several important B(C6F5)3-catalyzed reactions. Herein is described the synthesis of the triphenylsulfonium and diphenyliodonium salts of carbamato- and hydridoborates, their establishment as PhLAGs, and studies aimed at defining the mechanism of borane release. Factors affecting these photolytic reactions and the application of this concept to photoinduced hydrosilylation reactions and construction of siloxane scaffolds are also discussed.
Comparative Lewis acidity in fluoroarylboranes: B(o-HC6F 4)3, B(p-HC6F4)3, and B(C6F5)3
Morgan, Matthew M.,Marwitz, Adam J. V.,Piers, Warren E.,Parvez, Masood
, p. 317 - 322 (2013/02/25)
The Lewis acidic fluoroarylborane B(o-HC6F4) 3 (2) was prepared and its Lewis acid strength assessed in comparison to the known, related boranes B(C6F5)3 (1) and B(p-HC6F4/
A photo Lewis acid generator (PhLAG): Controlled photorelease of B(C 6F5)3
Khalimon, Andrey Y.,Piers, Warren E.,Blackwell, James M.,Michalak, David J.,Parvez, Masood
, p. 9601 - 9604 (2012/07/14)
A molecule that releases the strong organometallic Lewis acid B(C 6F5)3 upon irradiation with 254 nm light has been developed. This photo Lewis acid generator (PhLAG) now enables the photocontrolled initiation of several reactions catalyzed by this important Lewis acid. Herein is described the synthesis of the triphenylsulfonium salt of a carbamato borate based on a carbazole function, its establishment as a PhLAG, and the application of the photorelease of B(C6F5) 3 to the fabrication of thin films of a polysiloxane material.
Metal-free carbon dioxide reduction and acidic C-H activations using a frustrated Lewis pair
Tran, Sophia D.,Tronic, Tristan A.,Kaminsky, Werner,Michael Heinekey,Mayer, James M.
, p. 126 - 132 (2011/06/24)
Activation of CO2 and acidic C-H bonds by the lutidine-tris(pentafluorophenyl)borane [Lut/B(C6F5) 3] frustrated Lewis pair (FLP) are described (lutidine = 2,6-dimethylpyridine). Lut/B(C6F5)
The mechanism of polymerization of butadiene by ligand-free nickel(II) complexes
O'Connor, Abby R.,White, Peter S.,Brookhart, Maurice
, p. 4142 - 4143 (2008/02/01)
The polymerization of 1,3-dienes has been well-studied using an array of metal-containing complexes. Although a variety of (π-allyl) Ni(II) catalysts have been shown to be active for diene polymerization, details concerning the mechanism of chain growth are largely speculative and supported primarily by DFT calculations. The observation by low-temperature NMR spectroscopy of the key intermediates and the catalyst resting states in the chain growth are described here and provide a more complete and detailed mechanism of butadiene polymerization. Copyright
Lewis Acid Properties of Tris(pentafluorophenyl)borane. Structure and Bonding in L-B(C6F5)3 Complexes
Jacobsen, Heiko,Berke, Heinz,D?ring, Steve,Kehr, Gerald,Erker, Gerhard,Fr?hlich, Roland,Meyer, Oliver
, p. 1724 - 1734 (2008/10/08)
A variety of donor adducts of tris(pentafluorophenyl)borane were experimentally generated by reaction of a Lewis base with an excess of B(C6F5)5 in pentane. In this way, nitrile complexes (C6F5)3B·NCR(R = CH3 1a, p-CH3-C6H4 1b, p-NO2-C6H4 1c), isonitrile complexes (C6F5)3B·CNR (R = C(CH3)3 3a, C(CH3)2CH2C(CH3)3 3b, 2,6-(CH3)2-C6H3 3c), and the phosphine adduct (C6F5)3B·P(C6H 5)3 (6) could be prepared. The compounds were characterized by IR and NMR spectroscopy and by X-ray structure analyses (1a, 1c, 3a, 3b, and 6). Coordination of the nitriles as well as the isonitriles to the neutral Lewis acid leads to a substantial increase in the C≡N bond strength. This is evident from a marked shift of the v?C≡N IR band to higher wavenumbers, and this interpretation is supported by the small but experimentally significant decrease of the C≡N bond length observed by X-ray diffraction. The experimental work is complemented by a density functional study on the model complexes (C6F5)3B·L, L = CNCH3, NCCH3, PH3, CO. A detailed analysis revealed that the bonding in (C6F5)3B·L complexes is mainly dominated by electrostatic interaction, which in turn is responsible for the observed structural and spectroscopic changes. In the context of this work, the bonding of the neutral B(C6F5)3 Lewis acid is compared to the positively charged organometallic d0-Cp3M+ system (M = Zr, Hf). It was found that electrostatic effects are more pronounced for B(C6Fs)3 than for the transition metal fragments. The question as to the existence of a nonclassical main group carbonyl complex, (C6F5)3B·CO, is addressed.
New organo-lewis acids. Tris(β-perfluoronaphthyl)borane (PNB) as a highly active cocatalyst for metallocene-mediated ziegler-natta α-olefin polymerization
Li, Liting,Marks, Tobin J.
, p. 3996 - 4003 (2008/10/08)
Tris(β-perfluoronaphthyl)borane (B(C10F7)3, PNB) is synthesized from β-perfluoronaphthyllithium and BCl3 to serve as a new strong organo-Lewis acid cocatalyst. PNB efficiently activates a variety of group 4 dimethyl complexes to form highly active homogeneous Ziegler-Natta olefin polymerization catalysts. Reaction of PNB with rac-Me2Si(Ind)2ZrMe2 and CGCMMe2 (M = Zr, Ti; CGC = Me2Si(η5-Me4C5)( tBuN)) (1:1 molar ratio) rapidly produces the base-free cationic complexes rac-Me2Si(Ind)2ZrMe+MePNB- (1) and CGCMMe+MePNB- (M = Zr, 2; Ti, 3), respectively. The μ-methyl dinuclear cationic complex [(CGCTiMe)2(μ-Me)]+MePNB- (4) is formed when a 2:1 CGCTiMe2:PNB stoichiometry is employed: In the case of group 4 dimethyl zirconocenes, L2ZrMe2 (L = η5-C5H5, Cp; η5-1,2-Me2C5H3, Cp″), reaction in a 1:1 metallocene:PNB ratio affords cationic complexes L2ZrMe+MePNB- (L = Cp, 5; Cp″, 6), while the reaction with a 1:2 molar ratio affords dinuclear μ-methyl cationic complexes [(L2ZrMe)2(μ-Me)]+MePNB- (L = Cp, 7; Cp″, 8). In both reactions, μ-F dinuclear cationic complexes [(L2ZrMe)2(M-F)]+MePNB- (L = Cp, 9; Cp″, 10) are formed as byproducts. (C6F5)3BNCCH3 and PNBNCCH3 were synthesized and characterized. Analysis of the PNBNCCH3 + B(C6F5)3 ? (C6F5)3BNCCH3 + PNB equilibrium yields ΔH° = +0.7(2) kcal/ mol and ΔS° = +4.3(5) eu, suggesting PNB has somewhat higher Lewis acidity and is sterically more encumbered than B(C6F5)3. Solution ν(CN) values for PNBNCCH3 and (C6F5)3-BNCCH3 are 2365.3 and 2366.5 cm-1, respectively, which indicate strong Lewis acidity. PBBNCCH3 cannot be detected in the reaction of (C6F5)3BNCCH3 with PBB [PBB = tris-(2,2′,2″-perfluorobipheny)lborane] over prolonged periods at 60°C. In ethylene polymerization, PNB-derived cationic complexes 5, 6, 7, and 8 have catalytic activities similar to the B(C6F5)3-derived analogues, while 2 and 3 have substantially higher activities. In propylene polymerization, catalyst 1 has higher activity than the B(C6F5)3 analogue. In the case of ethylene and 1-hexene copolymerization, PNB-derived cationic complex 3 exhibits higher polymerization activity with similar 1-hexene incorporation versus the B(C6F5)3-derived cationic complex. In large-scale batch copolymerizations of ethylene and 1-octene mediated by CGCTiMe2, the PNB-based catalytic systems exhibit approximately twice the activity of the B(C6F5)3-based systems.
