Tetrakis Pentafluorophenyl Borate Research Articles

Photocationic Initiator Induced Synergy for High‐Performance Perovskite Solar Cells

The perovskite structures are prone to decomposition due to the formation of defect sites under various stressors. As a result, the stability of perovskite materials has been an Achilles’ heel in actual commercialization. Herein, photocationic initiator based on 4‐isopropyl‐4'‐methyldiphenyliodonium tetrakis(pentafluorophenyl)borate (TPFB) is introduced into perovskite film through the antisolvent process to enhance the efficiency and stability of perovskite solar cells. The hypervalent iodine part serves as a Lewis acid to passivate the negatively charged defects, while the pentafluorophenyl borate part is used to tailor the crystallization process by forming strong hydrogen bonding. Furthermore, the superior hydrophobicity of TPFB insulates the perovskite films. The resulted MAPbI3 devices show maximum power conversion efficiency (PCE) reaching 20.41% and ultrahigh open voltage (Voc) up to 1.15 V with the remaining 85% efficiency after 1000 h shelf storage. Furthermore, by introducing TPFB through a simple posttreatment process, the device delivers a PCE of 23.4% (steady‐state PCE of 23.2%), features useful for advanced double cation‐based perovskite device. In sum, these findings develop a universal passivation strategy and open a novel field of Lewis acid‐based passivation agent.

Improvement of catalytic activity for α‐diimine nickel complex with active sites stabilized by bulky boron counterions at elevated temperature

Three α‐diimine Ni (II) catalysts (Cat.1, Cat.2 and Cat.3) were synthesized and investigated for ethylene polymerization using alkyl aluminum and organoboron compounds as binary cocatalyst. The effects of different alkyl aluminum and boron complexes on ethylene polymerization catalyzed by Cat.1, Cat.2, and Cat.3 were studied. The sodium tetrakis[3,5‐bis (trifluoromethyl)phenyl]borate (NaBArF) was found to have best promotion for the catalytic activity of Cat.1, compared to negative effect of dimethylanilinium tetrakis (pentafluorophenyl)borate (TTB) and trityl tetrakis (pentafluorophenyl)borate (AB). All the three catalysts showed higher catalytic activity when NaBArF was introduced into the catalytic system, especially for Cat.3 (increased by 41.3% at 70°C). There was still minor increase of the catalytic activity for Cat.2 which have much better thermostability than Cat.3. The charging sequence of NaBArF and the [B]/[Ni] ratio have significant effects on the catalytic activity. The better catalytic performance of Cat.1/AlEt2Cl/NaBArF could be explained by its ability to raise the number of active centers. Namely, the molar percentage of active centers of Cat.1/AlEt2Cl/NaBArF was still above 30%, which was 1.7 times that of Cat.1/AlEt2Cl even if polymerization ran up to 30 min based on 2‐thiophenecarbonyl chloride (TPCC) quench‐labeling method. Lower [Al]/[Ni] ratio but more active centers and longer active centers lifetime of this binary cocatalyst is promising for improving the activity of ethylene polymerization industrially at elevated temperature.

Selective removal of alkali metal cations from multiply-charged ions via gas-phase ion/ion reactions using weakly coordinating anions.

Selective removal of alkali metal cations from mixed cation multiply-charged peptide ions is demonstrated here using gas-phase ion/ion reactions with a series of weakly coordinating anions (WCAs), including hexafluorophosphate (PF6 (-)), tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF), tetrakis(pentafluorophenyl)borate (TPPB), and carborane (CHB11Cl11 (-)). In all cases, a long-lived complex is generated by dication/anion condensation followed by ion activation to compare proton transfer with alkali ion transfer from the peptide to the anion. The carborane anion was the only anion studied to undergo dissociation exclusively through loss of the metallated anion, regardless of the studied metal adduct. All other anions studied yield varying abundances of protonated and metallated peptide depending on the peptide sequence and the metal identity. Density functional theory calculations suggest that for the WCAs studied, metal ion transfer is most strongly favored thermodynamically, which is consistent with the experimental results. The carborane anion is demonstrated to be a robust reagent for the selective removal of alkali metal cations from peptide cations with mixtures of excess protons and metal cations.

ω-Dimethyl ammonium tetrakis-pentafluorophenyl borate polyisoprene as an organic template for alkylated metallocenes toward the synthesis of polyethylene beads

In this work, we report the self-assembly in heptane of ω-dimethyl ammonium tetrakis-pentafluorophenyl borate polyisoprenes into micellar aggregates and the use of these nano-objects to support alkylated metallocenes toward ethylene polymerization. Dynamic light scattering was used to demonstrate the self-assembly and the formation of the micellar structures having a core of polar dimethyl ammonium tetrakis-pentafluorophenyl borate moieties, and a corona of polyisoprene (PI). The latter were then used as organic supports for alkylated metallocenes to produce unprecedented millimetric polyethylene beads without loss of catalytic activity.

The first silatropylium ion stabilized by rigid σ-frameworks: preparation, properties, and some reactions

The first cyclic π-conjugated silylium ion, the silatropylium ion 5 annelated with three bicyclo[2.2.2]octene units having a mesityl group on the silicon atom, was prepared with tetrakis(pentafluorophenyl)borate (TPFPB) as a counter anion in CD 2Cl 2 at −50°C by hydride abstraction from the corresponding silacycloheptatriene (silepin). The observed chemical shifts of 1H, 13C, and 29Si NMR for cation 5 were in agreement with the calculated values. These results and NICS calculations indicated that cation 5 has the aromaticity approaching that of the tropylium ion. When cation 4 having a methyl group instead of a mesityl group and cation 5 were generated in the presence of two equivalents of acetonitrile, the acetonitrile complexes 16 and 17 with considerable covalent-bond character were formed. For the complexes 16 and 17, the exchange process of acetonitrile was observed for the first time as an acetonitrile complex of a silyl cation, and the intermediacy of a pentavalent silicon was demonstrated. When cations 4 and 5 were generated by the use of triphenylmethyl perchlorate instead of triphenylmethyl TPFPB, covalent perchlorate esters 18 and 19 having the O–Si covalent bond were formed instead of ionic salts. By treatment with water, the perchlorate ester 18 was found to undergo a novel rearrangement to give a cyclopentene derivative 20a spiro-connected with bicyclo[2.2.2]octane at the 3-position.

Beta-Silyl and beta-Germyl Carbocations Stable at Room Temperature.

Stable carbocations have been prepared at room temperature with benzene as solvent and tetrakis(pentafluorophenyl)borate (TPFPB) as anion by the addition of solvated triethylsilylium TPFPB or of tributylgermylium TPFPB to 1,1-diphenylethene. These carbocations are stabilized by sigma conjugation with nonadjacent group 14 atoms and respectively constitute stable saturated beta-silyl and beta-germyl carbocations. NMR parameters, including the (29)Si chemical shift, the (13)C chemical shifts of the cationic, aryl, and methylene carbons, and the one-bond (13)C-(1)H coupling constant of the methylene group adjacent to the group 14 element, define the distribution of positive charge between carbon and (through sigma conjugation) silicon or germanium. The extent of hyperconjugation is estimated quantitatively by comparison with models. The NMR parameters indicate that the cations are open rather than bridged.