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1.
Langmuir monolayer and Gibbs layer exhibit surface‐active properties and it can be used as simple model systems to investigate the physicochemical properties of biological membranes. In this report, we presented the OH stretching vibration of H2O in the 4′′‐n‐pentyl‐4‐cyano‐p‐terphenyl (5CT), nonadecanenitrile (C18CN) Langmuir monolayer and compared them with CH3CN Gibbs layer at the air/water interface with polarization SFG‐VS. This study demonstrated that the hydrogen bond network is different in the Langmuir monolayer of 5CT, C18CN from CH3CN Gibbs layer at the air/water interface which showed two different water structures on the different surface layer. The results provided a deeper insight into understanding the hydrogen bond on the interfaces. 相似文献
2.
Dr. Artem Kovalenko Dr. Prasad Polavarapu Dr. Jean‐Louis Gallani Dr. Geneviève Pourroy Dr. Gilles Waton Dr. Marie Pierre Krafft 《Chemphyschem》2014,15(12):2440-2444
We show that water‐soluble monosodic salts of F‐alkyl phosphates CnF2n+1(CH2)2OP(O)(OH)2, with n=8 and 10 (F8H2Phos and F10H2Phos) form Gibbs films with exceptionally high dilational viscoelastic modules E that reach ~900 mN m?1 in the condensed phases. These E values are up to one order of magnitude larger than those recorded for phospholipid, protein and polymer films commonly considered as highly viscoelastic. F8H2Phos.1Na undergoes a transition between a liquid‐expanded and a liquid‐condensed phase. In the case of F10H2Phos.1Na, a transition occurs between a gas phase of surface domains, in which the molecules are densely packed, and a liquid‐condensed phase. 相似文献
3.
Caroline de Gracia Lux Jean‐Louis Gallani Dr. Gilles Waton Dr. Marie Pierre Krafft Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(24):7186-7198
Understanding and controlling the molecular organization of amphiphilic molecules at interfaces is essential for materials and biological sciences. When spread on water, the model amphiphiles constituted by CnF2n+1CmH2m+1 (FnHm) diblocks spontaneously self‐assemble into surface hemimicelles. Therefore, compression of monolayers of FnHm diblocks is actually a compression of nanometric objects. Langmuir films of F8H16, F8H18, F8H20, and F10H16 can actually be compressed far beyond the “collapse” of their monolayers at ~30 Å2. For molecular areas A between 30 and 10 Å2, a partially reversible, 2D/3D transition occurs between a monolayer of surface micelles and a multilayer that coexist on a large plateau. For A<10 Å2, surface pressure increases again, reaching up to ~48 mN m?1 before the film eventually collapses. Brewster angle microscopy and AFM indicate a several‐fold increase in film thickness when scanning through the 2D/3D coexistence plateau. Compression beyond the plateau leads to a further increase in film thickness and, eventually, to film disruption. Reversibility was assessed by using compression–expansion cycles. AFM of F8H20 films shows that the initial monolayer of micelles is progressively covered by one (and eventually two) bilayers, which leads to a hitherto unknown organized composite arrangement. Compression of films of the more rigid F10H16 results in crystalline‐like inflorescences. For both diblocks, a hexagonal array of surface micelles is consistently seen, even when the 3D structures eventually disrupt, which means that this monolayer persists throughout the compression experiments. Two examples of pressure‐driven transformations of films of self‐assembled objects are thus provided. These observations further illustrate the powerful self‐assembling capacity of perfluoroalkyl chains. 相似文献
4.
Glen B. Deacon Penny R. Drago Dirk Gbbels Mathias S. Wickleder Gerd Meyer 《无机化学与普通化学杂志》2001,627(5):811-813
From the reaction of PtCl2(hex) (hex = hexa‐1,5‐diene) with LiC6F5 in diethyl ether, the complex [Pt{CH(CH2C6F5)CH2CH2CH=CH2}(C6F5)(OH2)] ( 1 ) was isolated. The crystal structure (monoclinic, C2/c (no. 15), Z = 8, a = 15.241(3), b = 16.579(2), c = 16.225(2) Å, β = 111.12(2)°) shows a complex with square planar coordination around platinum with a template formed 1‐pentafluorophenylhex‐5‐en‐2‐yl ligand, and C6F5 and aqua ligands trans to the double bond and alkyl carbon, respectively. 相似文献
5.
Single‐Step Gas‐Phase Polyperfluoroalkylation of Naphthalene Leads to Thermodynamic Products 下载免费PDF全文
Long K. San Eric V. Bukovsky Dr. Igor V. Kuvychko Dr. Alexey A. Popov Prof. Steven H. Strauss Dr. Olga V. Boltalina 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(15):4373-4379
High‐temperature gas‐phase, solvent‐ and catalyst‐free reaction of naphthalene with an excess of RFI reagent (RF?CF3, C2F5, n‐C3F7, and n‐C4F9) was used for the first time to produce a series of highly perfluoroalkylated naphthalene products NAPH(RF)n with n=2–5. Four 95+ % pure 1,3,5,7‐NAPH(RF)4 with RF?CF3, C2F5, n‐C3F7, and n‐C4F9 were isolated using a simple chromatography‐free procedure. These new compounds were fully characterized by 19F and 1H NMR spectroscopy, X‐ray crystallography (for RF?CF3 and C2F5), atmospheric‐pressure chemical ionization mass spectrometry, and cyclic and square‐wave voltammetry. DFT calculations confirm that the proposed synthesis yields the most stable isomers that have not been accessed by alternative preparation techniques. 相似文献
6.
Dr. Olga Ekkert Christopher B. Caputo Conor Pranckevicius Dr. Constantin G. Daniliuc Dr. Gerald Kehr Prof. Dr. Gerhard Erker Prof. Dr. Douglas W. Stephan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11287-11290
The reactions of the intramolecular frustrated Lewis pair‐adduct Ph2PC(p‐Tol)?C(C6F5)B(C6F5)2(CNtBu) with XeF2 gave Ph2P(F)C(p‐Tol)?C(C6F5)B(F)(C6F5)2 ( 3 ). This species reacts with two equivalents of Al(C6F5)3?C7H8 producing the salt, [Ph2P(F)C(p‐Tol)?C(C6F5)B(C6F5)2][F(Al(C6F5)3)2] ( 4 ), whereas reaction with HSiEt3/B(C6F5)3 gave Ph2P(F)C(p‐Tol)?C(H)B(C6F5)3 ( 5 ). The photolysis of 3 resulted in aromatization affording the phenanthralene derivative Ph2P(F)C(p‐Tol(o‐C6F4))?CB(F)(C6F5)2 ( 6 ). 相似文献
7.
Daniel Winkelhaus Beate Neumann Dr. Hans‐Georg Stammler Dr. Raphael J. F. Berger Dr. Yuri V. Vishnevskiy Prof. Dr. Norbert W. Mitzel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(30):9312-9320
The reaction of (C6F5)2BH ( 1 ) with N,N‐dimethylallylamine ( 2 ), N,N‐diethylallylamine ( 3 ) and 1‐allylpiperidine ( 4 ) afforded the five‐membered ring systems (C6F5)2B(CH2)3NR2 (R=Me ( 5 ), Et ( 6 )) and (C6F5)2B(CH2)3N(CH2)5 ( 7 ) with an intramolecular dative B? N bond. A different product was obtained from the reaction of (C6F5)2BH ( 1 ) with N,N‐diisopropylallylamine ( 8 ), which afforded the seven‐membered ring system (C6F5)2B(CH2)3N(iPr)CH(Me)CH2 ( 9 ) under extrusion of dihydrogen. All compounds were characterised by elemental analysis, NMR spectroscopy and single‐crystal X‐ray diffraction experiments. Density functional theory (DFT) studies were performed to rationalise the different reaction mechanism for the formation of products 6 and 9 . The bonding situation of compound 9 was analysed in terms of its electron density topology to describe the delocalised nature of a borane– enamine adduct. 相似文献
8.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(4):513-522
J147 [N‐(2,4‐dimethylphenyl)‐2,2,2‐trifluoro‐N′‐(3‐methoxybenzylidene)acetohydrazide] has recently been reported as a promising new drug for the treatment of Alzheimer's disease. The X‐ray structures of seven new 1,4‐diaryl‐5‐trifluoromethyl‐1H‐1,2,3‐triazoles, namely 1‐(3,4‐dimethylphenyl)‐4‐phenyl‐5‐trifluoromethyl‐1H‐1,2,3‐triazole (C17H14F3N3, 1 ), 1‐(3,4‐dimethylphenyl)‐4‐(3‐methoxyphenyl)‐5‐trifluoromethyl‐1H‐1,2,3‐triazole (C18H16F3N3O, 2 ), 1‐(3,4‐dimethylphenyl)‐4‐(4‐methoxyphenyl)‐5‐trifluoromethyl‐1H‐1,2,3‐triazole (C18H16F3N3O, 3 ), 1‐(2,4‐dimethylphenyl)‐4‐(4‐methoxyphenyl)‐5‐trifluoromethyl‐1H‐1,2,3‐triazole (C18H16F3N3O, 4 ), 1‐[2,4‐bis(trifluoromethyl)phenyl]‐4‐(3‐methoxyphenyl)‐5‐trifluoromethyl‐1H‐1,2,3‐triazole (C18H10F9N3O, 5 ), 1‐(3,4‐dimethoxyphenyl)‐4‐(3,4‐dimethoxyphenyl)‐5‐trifluoromethyl‐1H‐1,2,3‐triazole (C19H18F3N3O4, 6 ) and 3‐[4‐(3,4‐dimethoxyphenyl)‐5‐(trifluoromethyl)‐1H‐1,2,3‐triazol‐1‐yl]phenol (C17H14F3N3O3, 7 ), have been determined and compared to that of J147 . B3LYP/6‐311++G(d,p) calculations have been performed to determine the potential surface and molecular electrostatic potential (MEP) of J147 , and to examine the correlation between hydrazone J147 and the 1,2,3‐triazoles, both bearing a CF3 substituent. Using MEPs, it was found that the minimum‐energy conformation of 4 , which is nearly identical to its X‐ray structure, is closely related to one of the J147 seven minima. 相似文献
9.
The dissolution of (perfluoroorgano)difluoroboranes RFBF2 in anhydrous HF (aHF) resulted in equilibrium mixtures of the starting borane and different kinds of acid‐base products: [H2F] [RFBF2(F · HF)] (RF = C6F5, cis‐C2F5CF=CF, trans‐C4F9CF=CF) or [H2F] [RFBF3] (RF = C6F13). In aHF the aryl compounds C6F5BF2 and K [C6F5BF3] showed two parallel reactivities with XeF2: xenodeborylation (formation of the [C6F5Xe]+ cation) and fluorine addition to the aryl group. In aHF perfluoroalk‐1‐enyldifluoroboranes RFBF2 as well as potassium perfluoroalk‐1‐enyltrifluoroborates K [RFBF3] (RF = cis‐C2F5CF=CF, trans‐C4F9CF=CF) underwent only fluorine addition across the carbon‐carbon double bond under the action of XeF2. Potassium perfluorohexyltrifluoroborate K [C6F13BF3] did not react with XeF2 in aHF. 相似文献
10.
Schäfer A Winter F Saak W Haase D Pöttgen R Müller T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(39):10979-10984
The reactivity of aryl‐substituted stannylenes, Ar2Sn ( 4 ), towards silylarenium borates, [R3SiArH][B(C6F5)4] ( 3 ), was investigated. The reaction with 2,3,4‐trimethyl‐6‐tert‐butylphenyl (mebp)‐substituted stannylene gave silyl‐substituted stannylium ions 2 a , b , which were characterized by NMR spectroscopy supported by the results of quantum‐mechanical computations of molecular structures and magnetic properties. The tri‐iso‐propylphenyl‐substituted stannylium ions 2 c , d undergo a decomposition reaction in toluene to give the dicationic tin–arene complex [Sn(C7H8)3]2+ ( 5 ) in the form of the [B(C6F5)4] salt in high yields. The 5 [B(C6F5)4]2 salt was identified by single crystal X‐ray diffraction analysis and by Mössbauer spectroscopy. The bonding situation was investigated by using natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) calculations. The substitution of the weakly coordinating borate anion by the carboranate [CB11H6Br6]? results in replacement of the toluene ligands and formation of tin(II) carboranate with only weak Sn2+–anion interactions as suggested by the solid‐state structure of the isolated salt. 相似文献
11.
Rui‐Yan Li Bing‐Qiang Wang Zhi‐Ru Li Di Wu Ying Li 《International journal of quantum chemistry》2008,108(1):151-160
Using the counterpoise‐corrected potential energy surface method, the stationary structures of the π Br‐bond complexes C2H4‐nFn? BrF (n = 0–2) with all real frequencies have been obtained at MP2/aug‐cc‐pVDZ level. The order of the π Br‐bond length is 2.625 Å (C2H4? BrF) < 2.714 Å (C2H3F? BrF) < 2.751 Å (g‐C2H2F2? BrF) < 2.771 Å (trans‐C2H2F2? BrF) < 2.778 Å (cis‐C2H2F2? BrF). The interaction energies (Eint) are, respectively,‐5.9 (C2H4? BrF),‐4.4 (C2H3F? BrF),‐3.7 (g‐C2H2F2? BrF),‐3.1 (cis‐C2H2F2? BrF),‐2.8 kcal/mol (trans‐C2H2F2? BrF), at the CCSD (T)/aug‐cc‐pVDZ level, which include larger electron correlation contributions (Ecorre). The order of Ecorre is‐3.40 (C2H4? BrF),‐3.60 (C2H3F? BrF),‐3.85 (g‐C2H2F2? BrF),‐3.86 (cis‐C2H2F2? BrF),‐3.88 kcal/mol (trans‐C2H2F2? BrF). The earlier results show above that the F substituent effect elongates the π Br‐bond, reduces the Eint, and increases the Ecorre contribution of the interaction energy. Interestingly, the interaction energy of the cis‐C2H2F2? BrF structure with longer interaction distance is larger than that of the corresponding trans‐C2H2F2? BrF structure with shorter interaction distance. This reason comes from a special secondary interaction between lone pairs of Br atom with positive charge and some atoms (H, C) with positive charges of C2H2F2 in the cis‐C2H2F2? BrF structure. Comparing with corresponding C2H4‐nFn? ClF and C2H4‐nFn? HF, the C2H4‐nFn? BrF system has the larger Eint in which main contribution comes from the larger Ecorre, representing the larger dispersion interaction. The larger Ecorre contribution of the Eint of π Br‐bond can be used to understand that the π Br‐bond is shorter and stronger than corresponding π Cl‐bond. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 相似文献
12.
New Syntheses and Crystal Structures of Bis(fluorophenyl) Mercury, Hg(Rf)2 (Rf = C6F5, 2, 3, 4, 6‐F4C6H, 2, 3, 5, 6‐F4C6H, 2, 4, 6‐F3C6H2, 2, 6‐F2C6H3) Bis(fluorophenyl) mercury compounds, Hg(Rf)2 (Rf = C6F5, C6HF4, C6H2F3, C6H3F2), are prepared in good yields by the reactions of HgF2 with Me3SiRf. The crystal structures of Hg(2, 3, 4, 6‐F4C6H)2 (monoclinic, P21/n), Hg(2, 3, 5, 6‐F4C6H)2 (monoclinic, C2/m), Hg(2, 4, 6‐F3C6H2)2 (monoclinic, P21/c) and Hg(2, 6‐F2C6H3)2 (triclinic, P1) are described. 相似文献
13.
Moumita Pait Gargi Kundu Srinu Tothadi Suvendu Karak Shailja Jain Kumar Vanka Sakya S. Sen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9):2830-2834
The reaction of SIPr, [1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene] ( 1 ), with C6F6 led to the formation of an unprecedented mesoionic compound ( 2 ). The formation of 2 is made accessible by deprotonation of the SIPr backbone with simultaneous elimination of HF. The C?F bond para to the imidazolium ring in 2 is only of 1.258(4) Å, which is the one of the shortest structurally authenticated C?F bonds known to date. The liberation of HF during the reaction is unequivocally proved by the addition of one more equivalent of SIPr, which leads to the imidazolium salt with the HF2? anion. To functionalize 2 , the latter reacted with B(C6F5)3 to give an unusual donor–acceptor compound, where the fluoride atom from the C6F5 moiety coordinates to B(C6F5)3 and the carbanion moiety remains unaffected. Such coordination susceptibility of the fluoride atom of a nonmetallic system to a main‐group Lewis acid (Fnon‐metal→BR3) is quite unprecedented. 相似文献
14.
Nadezhda B. Tamm Dr. Lev N. Sidorov Prof. Dr. Erhard Kemnitz Prof. Dr. Sergey I. Troyanov Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(40):10486-10492
Perfluoroalkylation of a higher fullerene mixture with CF3I or C2F5I, followed by HPLC separation of CF3 and C2F5 derivatives, resulted in the isolation of several C84(RF)n (n=12, 16) compounds. Single‐crystal X‐ray crystallography with the use of synchrotron radiation allowed structure elucidation of eight C84(RF)n compounds containing six different C84 cages (the number of the C84 isomer is given in parentheses): C84 (23)(C2F5)12 ( I ), C84 (22)(CF3)16 ( II ), C84 (22)(C2F5)12 ( III ), C84 (11)(C2F5)12 ( IV ), C84 (16)(C2F5)12 ( V ), C84 (4)(CF3)12 ( VI with toluene and VII with hexane as solvate molecules), and C84 (18)(C2F5)12 ( VIII ). Whereas some connectivity patterns of C84 isomers (22, 23, 11) had previously been unambiguously confirmed by different methods, derivatives of C84 isomers numbers 4, 16, and 18 have been investigated crystallographically for the first time, thus providing direct proof of the connectivity patterns of rare C84 isomers. General aspects of the addition of RF groups to C84 cages are discussed in terms of the preferred positions in the pentagons under the formation of chains, pairs, and isolated RF groups. 相似文献
15.
The hydrodeboration of the (fluoroorgano)trifluoroborates K [RFBF3] [RF = C6F5, XCF=CF (X = F, cis‐ and trans‐Cl, C3F7O, cis‐C2F5, trans‐C4F9, ‐C4H9) and C6F13] and of the organotrifluoroborates K [RBF3] (R = C6H5, cis‐ and trans‐C4H9CH=CH, C4H9 and C8H17) with CH3CO2H (100 %), CF3CO2H (100 %), aqueous HF and anhydrous HF was investigated. In the alkenyltrifluoroborates K [R'CF=CFBF3] the formal replacement of BF3 by a proton occurred stereospecifically under retention of the configuration. The 19F NMR spectra of K [RFBF3] in acids indicate strong interactions of the BF3 group with protons or acid molecules. 相似文献
16.
Autoinduced Catalysis and Inverse Equilibrium Isotope Effect in the Frustrated Lewis Pair Catalyzed Hydrogenation of Imines 下载免费PDF全文
Dipl.‐Chem. Sebastian Tussing Dr. Lutz Greb Dipl.‐Chem. Sergej Tamke Dr. Birgitta Schirmer Priv.‐Doz. Claudia Muhle‐Goll Prof. Dr. Burkhard Luy Prof. Dr. Jan Paradies 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8056-8059
The frustrated Lewis pair (FLP)‐catalyzed hydrogenation and deuteration of N‐benzylidene‐tert‐butylamine ( 2 ) was kinetically investigated by using the three boranes B(C6F5)3 ( 1 ), B(2,4,6‐F3‐C6H2)3 ( 4 ), and B(2,6‐F2‐C6H3)3 ( 5 ) and the free activation energies for the H2 activation by FLP were determined. Reactions catalyzed by the weaker Lewis acids 4 and 5 displayed autoinductive catalysis arising from a higher free activation energy (2 kcal mol?1) for the H2 activation by the imine compared to the amine. Surprisingly, the imine reduction using D2 proceeded with higher rates. This phenomenon is unprecedented for FLP and resulted from a primary inverse equilibrium isotope effect. 相似文献
17.
Damir Barisic David Schneider Ccilia Maichle‐Mssmer Reiner Anwander 《Angewandte Chemie (International ed. in English)》2019,58(5):1515-1518
The half‐open rare‐earth‐metal aluminabenzene complexes [(1‐Me‐3,5‐tBu2‐C5H3Al)(μ‐Me)Ln(2,4‐dtbp)] (Ln=Y, Lu) are accessible via a salt metathesis reaction employing Ln(AlMe4)3 and K(2,4‐dtbp). Treatment of the yttrium complex with B(C6F5)3 and tBuCCH gives access to the pentafluorophenylalane complex [{1‐(C6F5)‐3,5‐tBu2‐C5H3Al}{μ‐C6F5}Y{2,4‐dtbp}] and the mixed vinyl acetylide complex [(2,4‐dtbp)Y(μ‐η1:η3‐2,4‐tBu2‐C5H4)(μ‐CCtBu)AlMe2], respectively. 相似文献
18.
Natesan Thirupathi Dino Amoroso Andrew Bell John D. Protasiewicz 《Journal of polymer science. Part A, Polymer chemistry》2009,47(1):103-110
The catalytic efficacy of trans‐[(R3P)2Pd(O2CR′)(LB)][B(C6F5)4] ( 1 ) (LB = Lewis base) and [(R3P)2Pd(κ2‐O,O‐O2CR′)][B(C6F5)4] ( 2 ) for mass polymerization of 5‐n‐butyl‐2‐norbornene (Butyl‐NB) was investigated. The nature of PR3 and LB in 1 and 2 are the most critical components influencing catalytic activity/latency for the mass polymerization of Butyl‐NB. Further, it was shown that 1 is in general more latent than 2 in mass polymerization of Butyl‐NB. 5‐n‐Decyl‐2‐norbornene (Decyl‐NB) was subjected to solution polymerization in toluene at 63(±3) °C in the presence of several of the aforementioned palladium complexes as catalysts and the polymers obtained were characterized by gel permeation chromatography. Cationic trans‐[(R3P)2PdMe(MeCN)][B(C6F5)4] [R = Cy ( 3a ), and iPr ( 3b )] and trans‐[(R3P)2PdH (MeCN)][B(C6F5)4] [R = Cy ( 4a ), and iPr ( 4b )], possible products from thermolysis of trans‐[(R3P)2Pd(O2CMe)(MeCN)][B(C6F5)4] [R = Cy ( 1a ) and iPr ( 1g )], as well as trans‐[(R3P)2Pd(η3‐C3H5)][B(C6F5)4] [R = Cy ( 5a ), and iPr ( 5b )], were also examined as catalysts for solution polymerization of Decyl‐NB. A maximum activity of 5360 kg/(molPd h) of 2a was achieved at a Decyl‐NB/Pd: 26,700 ratio which is slightly better than that achieved with 5a [activity: 5030 kg/(molPd h)] but far less compared with 4a [activity: 6110 kg/(molPd h)]. Polydispersity values indicate a single highly homogeneous character of the active catalyst species. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 103–110, 2009 相似文献
19.
Synthesis,Structure, and Reactivity of Diazene Adducts: Isolation of iso‐Diazene Stabilized as a Borane Adduct 下载免费PDF全文
Dipl.‐Chem. Fabian Reiß Prof. Dr. Axel Schulz Dr. Alexander Villinger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11800-11811
This work describes the synthesis and full characterization of a series of GaCl3 and B(C6F5)3 adducts of diazenes R1?N?N?R2 (R1=R2=Me3Si, Ph; R1=Me3Si, R2=Ph). Trans‐Ph?N?N?Ph forms a stable adduct with GaCl3, whereas no adduct, but instead a frustrated Lewis acid–base pair is formed with B(C6F5)3. The cis‐Ph?N?N?Ph ? B(C6F5)3 adduct could only be isolated when UV light was used, which triggers the isomerization from trans‐ to cis‐Ph?N?N?Ph, which provides more space for the bulky borane. Treatment of trans‐Ph?N?N?SiMe3 with GaCl3 led to the expected trans‐Ph?N?N?SiMe3 ? GaCl3 adduct but the reaction with B(C6F5)3 triggered a 1,2‐Me3Si shift, which resulted in the formation of a highly labile iso‐diazene, Me3Si(Ph)N?N; stabilized as a B(C6F5)3 adduct. Trans‐Me3Si?N?N?SiMe3 forms a labile cis‐Me3Si?N?N?SiMe3 ? B(C6F5)3 adduct, which isomerizes to give the transient iso‐diazene species (Me3Si)2N?N ? B(C6F5)3 upon heating. Both iso‐diazene species insert easily into one B?C bond of B(C6F5)3 to afford hydrazinoboranes. All new compounds were fully characterized by means of X‐ray crystallography, vibrational spectroscopy, CHN analysis, and NMR spectroscopy. All compounds were further investigated by DFT and the bonding situation was assessed by natural bond orbital (NBO) analysis. 相似文献
20.
Youngchan Jang Dai Seung Choi Shin Han 《Journal of polymer science. Part A, Polymer chemistry》2004,42(5):1164-1173
The activation of a metal alkyl‐free Ni‐based catalyst with B(C6F5)3 was investigated in the polymerization of 1,3‐butadiene. A catalyst of bis(1,5‐cyclooctadiene)nickel (Ni(COD)2)/B(C6F5)3 was found to have high catalytic activity and 1,4‐cis stereoregularity. The catalyst was also found to provide polybutadiene having a molecular weight (Mw) of up to 117,000, even in the absence of AlR3 and MAO. Variations in the mol ratio of B(C6F5)3 to Ni affected catalytic activity, 1,4‐cis stereoregularity, and the Mw of polybutadiene, while the molecular weight distribution (MWD) of polybutadiene showed little correlation with the mol ratio of B(C6F5)3 to Ni. The use of other borane compounds such as B(C6H5)3, BEt3, and BF3 etherate in place of B(C6F5)3 clearly showed the two main functions of B(C6F5)3 in the present catalyst. The high Lewis acidity of B(C6F5)3 enabled it to activate catalytic complexes, thus inducing the polymerization. The steric bulkiness of B(C6F5)3 suppressed chain transfer reactions, contributing to the production of polybutadiene with a high Mw. Kinetic studies showed that the catalyst had an induction period, possibly due to the time needed for the formation of catalytic complexes starting from Ni(COD)2. A plot of ?ln (1?X), where X is the fractional conversion, as a function of time resulted in a linear relationship, showing that the present catalyst system followed first‐order kinetics with respect to monomer concentration. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1164–1173, 2004 相似文献