1109-15-5Relevant articles and documents
The solid-state structure of bis(pentafluorophenyl)zinc
Sun, Yimin,Piers, Warren E.,Parvez, Masood
, p. 513 - 517 (1998)
Using the published method of Wiedenbruch, bis(pentafluorophenyl)zinc, 1, was prepared from anhydrous ZnCl2 and 2 equiv. of LiC6F5 in diethyl ether. Base-free 1 was obtained in 60-65% yield by repeated distillation of the initially formed bis(diethyl) ether adduct of 1. The X-ray quality crystals of 1 were obtained from benzene solution. The molecular structure of 1 revealed a near linear geometry for the two-coordinate zinc center (C(1)-Zn-C(7) = 172.6(2)°), typical of monomeric ZnR2 derivatives. In the crystal structure, stacking interactions between C6F5 rings on adjacent molecules is a dominant motif, with ring centroid to ring centroid distances of 3.503 and 3.563 A observed. A weak intermolecular C-F...Zn interaction between F(2) and an adjacent zinc center, as judged by the close contact of 2.849(2) A, also appears to be an important aspect of the crystal structure. Compound 1 is an effective but nonselective C6F5 transfer agent to BCl3; 1: monoclinic, space group P21/n, a = 11.902(2) A, b = 7.732(2) A, c = 13.735(2) A, β = 110.58(1)°, V = 1183.4(4) A3, Z = 4, R = 0.048, Rw = 0.069.
Synthesis and photophysical properties of imine borane adducts towards vapochromic materials
Soltani, Yashar,Adams, Samuel J.,B?rger, Jennifer,Wilkins, Lewis C.,Newman, Paul D.,Pope, Simon J.A.,Melen, Rebecca L.
, p. 12656 - 12660 (2018)
A series of alkynyl aryl conjugated aldehydes and imines were prepared and their adducts with various Lewis acidic boranes have been studied via NMR, absorption, and luminescence spectroscopies in solution. The imine-B(C6F5)3 adduct showed remarkable solution stability, and was then trialled in vapochromism experiments using simple impregnated paper strips to examine the fluorescence responses.
Silica-Grafted Borato Cocatalysts for Olefin Polymerization Modeled by Silsesquioxane Borato Complexes
Duchateau, Robbert,Van Santen, Rutger A.,Yap
, p. 809 - 816 (2000)
The syntheses and reactivity studies of silsesquioxane-borato complexes are described. Treatment of B(C6F5)3 with (c-C5H9)7Si8O12(OH) and (c-C5H9)7Si7O9(OH) 3 in the presence of a Br?nsted base yields the silsesquioxane-borates X+{[(c-C5H9)7Si8O 13]B(C6F5)3}- (1a, X+ = PhN(H)Me2+; 1b, X+ = Et3NH+) and X+{[(c-C5H9)7Si7(OH) 2O10]B(C6F5)3} - (1b, X+ = PhN-(H)Me2+; 2b, X+ = Et3NH+), respectively. When the more nucleophilic base pyridine is used, (C6F5)3B·NC5H5 (3) is formed instead, demonstrating the competition between B(C6F5)3 and H+ to react with the amine. The dimethylaniline in 1a and 2a is readily exchanged by NEt3 to form 1b and 2b. With the nucleophilic Lewis base NC5H5, the B-O bond in 1a and 2a is split, yielding (C6F5)3B·NC5H5 (3) and the free silsesquioxanes. Complexes 1 and 2 rapidly undergo hydrolysis under formation of the hydroxyl complexes X+{(C6F5)3BOH}- (4a, X+ = PhN(H)Me2+; 4b, X+ = Et3NH+). Likewise, alcoholysis of 1a and 2a with i-PrOH yields the alkoxide {PhN(H)Me2}+{i-PrOB(C6F5) 3}- (5). The B-O bond is only moderately stable toward early-transition-metal alkyls. Nevertheless, Cp2Zr(CH2Ph)2 + 1a and Zr(CH2Ph)4 + 2a form single-site ethylene polymerization catalysts. Detailed reactivity studies demonstrated that both B-O and B-C bond splitting plays a crucial role, as not 1a and 2a, but their decomposition product B(C6F5)3 is the actual cocatalyst. The solid-state structures of 1a and 4b were determined by single-crystal X-ray analysis.
Interaction of titanium(III) zwitterionic complex Cp[η 5-C5H4B(C6F5) 3]Ti with organic halides: Synthesis and X-ray crystal structure determination of zwitterionic titanocene monohalides
Strunkina,Minacheva,Lyssenko,Burlakov,Baumann,Arndt,Strunin,Shur
, p. 557 - 565 (2006)
The reaction of the titanium(III) zwitterionic complex Cp[η 5-C5H4B(C6F5) 3]Ti (1) with CCl4 at 20 °C under Ar results in the formation of hexachloroethane and the zwitterionic titanocene monochloride Cp[η5-C5H4B(C6F 5)3]TiCl (3) containing a B(C6F 5)3 moiety in the η5-cyclopentadienyl ring. Under similar conditions, the reaction of 1 with 1,2-dibromoethane affords ethylene and the corresponding zwitterionic monobromide Cp[η 5-C5H4B(C6F5) 3]TiBr (4). An X-ray diffraction study of 3 and 4 revealed the presence of a coordinative bond between the ortho-fluorine atom of one of the C6F5 substituents and the positively charged titanium centre. In the interaction of 1 with n-propyl iodide at 20 °C, titanocene diiodide, B(C6F5)3 and propylene are produced. The mechanism of this interesting reaction is discussed. The synthesized zwitterions 3 and 4 are able to catalyze the ring-opening polymerization of ε-caprolactone in a toluene solution and in bulk. The highest activity in this process is exhibited by 3. The first X-ray diffraction study of Cp 2TiI2 has been carried out.
Methane activation by a borenium complex
Liu, Yizhen,Dong, Weishi,Li, Zhen Hua,Wang, Huadong
, p. 1843 - 1851 (2021)
The selective functionalization of methane under ambient conditions remains a formidable challenge for chemists. While most studies have focused on transition metal complexes, much less attention has been devoted to molecular complexes based on non-metal elements, despite them being more sustainable and less environmentally impactful. Here, we report that an N-heterocyclic carbene-stabilized borenium complex can activate methane under relatively mild conditions. The resulting methylborenium complex can readily transfer the methyl group to catecholborane (HBcat), which can lead to a synthetic cycle for the conversion of methane to MeBcat. Both experimental and theoretical mechanistic studies suggest that the C–H bonds of methane are activated via a σ-bond metathesis pathway. Such direct aliphatic C–H borylation can be extended to other alkanes, such as ethane and octane. The formed alkylborenium complexes can react with terminal alkynes via 1,2-alkylboration to install both the alkyl and boryl functionalities onto organic scaffolds.
A Dimer of Hydrogen Cyanide Stabilized by a Lewis Acid
Bl?sing, Kevin,Bresien, Jonas,Labbow, René,Schulz, Axel,Villinger, Alexander
, p. 9170 - 9175 (2018)
A highly labile dimer of hydrogen cyanide, HCN???HCN, was extracted from liquid HCN by adduct formation with the bulky Lewis acid B(C6F5)3, affording HCN???HCN?B(C6F5)3, which was fully characterized. The influence of the solvent (HCN, CH2Cl2, and aromatic hydrocarbons) on the crystallization process was studied, revealing dimer formation when using HCN or CH2Cl2 as solvent, whereas aromatic hydrocarbons led to the formation of monomeric arene??HCN?B(C6F5)3 adducts, additionally stabilized by η6-coordination of the aromatic ring system similar to well-known half-sandwich complexes.
Silyl cations in the solid and in solution
Lambert, Joseph B.,Zhang, Shizhong,Ciro, Sol M.
, p. 2430 - 2443 (1994)
Reaction of silanes with triphenylmethyl tetrakis(pentafluorophenyl)borate (TPFPB) with excess silane as solvent yields a white solid that may be examined directly or dissolved for experiments in solution. The NMR properties of the material in a variety of solvents indicate that the anion is free and unperturbed by the presence of the silicon species. The 29Si chemical shift is highly dependent on the nucleophilicity of the solvent, with large downfield shifts (compared with the analogous silane, Δδ) in the order acetonitrile, sulfolane, toluene, benzene. The largest Δδ values for alkyl substituents in the arene solvents are ca. 100 ppm, far short of the expectation for a fully trigonal silylium ion. For tris(trimethylsilyl)silylium tetrakis-(pentafluorophenyl)borate, Δδ is 228.5 ppm, much closer to the trigonal ideal. The 29Si shifts of the solid, which had never been exposed to a solvent, are almost identical to those in benzene solution. For the case of methyldiisopropylsilane, with diastereotopic methyl groups, conversion to the TPFPB salt resulted in homotopic protons and carbons in a variety of solvents, which require a dynamic process between bound and unbound silyl species with a barrier of no more than about 13 kcal mol-1. The X-ray crystallographic structure of triethylsilylium tetrakis-(pentafluorophenyl)borate recrystallized from hexane/toluene contains silicon in a distorted pyramid with normal coordination to the methylene carbons (1.85 A?) and an experimentally unprecedented distant coordination to toluene (2.18 A?). This Si-C distance to the para position of toluene is equivalent to a bond order of 0.28 according to the Pauling equation. The coordinated toluene is planar and essentially unaltered by the interaction with silicon, in contrast to the crystal structures of known arenium ions (σ complexes). The solid state 13C spectrum indicates little transfer of positive charge to toluene. Thus the arenium ion model is rejected by experiment. The ions are best termed silyl cations with weak η1 π coordination to toluene.
Bissilylated halonium ions: [Me3Si-X- SiMe3][B(C 6F5)4] (X = F, Cl, Br, I)
Lehmann, Mathias,Schulz, Axel,Villinger, Alexander
, p. 7444 - 7447 (2009)
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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.
, p. 873 - 881 (2020)
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.
Metal-Free Iodoperfluoroalkylation: Photocatalysis versus Frustrated Lewis Pair Catalysis
Helmecke, Lucas,Spittler, Michael,Schmidt, Bernd M.,Czekelius, Constantin
supporting information, p. 123 - 134 (2020/09/02)
A comparison of two catalytic, metal-free iodoperfluoroalkylation protocols is presented. Frustrated Lewis pairs [ tBu 3P/B(C 6F 5) 3] or phosphines/phosphites under visible light irradiation efficiently mediate the functionalization of non-activated alkenes and alkynes. A comprehensive account of the corresponding substrate scopes as well as insights into the mechanistic details of both reaction pathways are provided.
A NEW METHOD OF 18F LABELLING AND INTERMEDIATE SALTS
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Page/Page column 37, (2021/06/26)
Disclosed herein is a salt of formula I: where R1, X, n, R, R1, Y, m, p, q, Z and o are as defined herein. Also disclosed herein are methods of using said salts in chemical synthesis, such as to prepare compounds isotopically enriched in 18F for use in PET imaging, as well as methods to make the compounds of formula I.
