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1.
The reaction of free tritiated phenylium ion, generated from nuclear decay of [l,4-T2]-benzene in the presence of simple gaseous hydrocarbons RH (R = CH3, C2H5, C3H7; partial pressure: 10-100 torr), yields predominantly the corresponding tritiated C6H5R products. The effects of gaseous nucleophilic acceptors (NuH = NH3, CH3OH) on the reaction with CH4, were also investigated. Phenylium ion confirms its exceedingly high reactivity even toward pure σ- -type substrates, as well as its considerable site selectivity, demonstrated by the distinct preference for the C-H bonds of the substrate. The stability features of the ionic intermediates from addition of phenylium ion with RH have been evaluated, as well as their fragmentation and isomerization mechanisms. The behaviour of phenylium ion toward simple aliphatic hydrocarbons in the gas phase (10-100 torr) is discussed and compared with previous mechanistic hypotheses from ICR mass spectrometric studies, carried out at much lower pressures (10-5 torr). 相似文献
2.
D. N. Bazhin T. I. Gorbunova A. Ya. Zapevalov V. I. Saloutin 《Russian Journal of Applied Chemistry》2005,78(10):1646-1650
Procedures for preparing polyfluorinated ethers H(CF2CF2) n CH2OR by alkylation of the corresponding telomeric alcohols H(CF2CF2) n CH2OH (n = 1–3) with alkyl halides and alkyl tosylates were examined. 相似文献
3.
The rate constants of the decay of carbocation generated in the photolysis of 2,2,4,6-tetramethyl-1,2-dihydroquinoline and the composition of reaction products were studied as a function of solvent composition in the mixtures H2O–ROH and MeOH–ROH (R = Et, n-Pr, and i-Pr). The rate constants of carbocation decay in alcohols are more than 20 times higher than the corresponding rate constants in water. As follows from the composition of the products obtained in the photolysis in the alcohol–water mixtures, MeOH is only 1.4 times more reactive than water, and EtOH and n-PrOH are even less active than water. The inconsistency in the product composition in the mixtures and the values of the observed rate constants in these solvents was explained by the two-step mechanism of the reaction: the reversible formation of an adduct of the carbocation with the solvent components and subsequent proton transfer to the solvent to form the final product, with the first step determining the product composition and the second step determining the rate of carbocation decay. The relative rate constants of alcohols and water were determined for the two steps. The preferred solvation of the carbocation with water also contributes significantly to the reaction kinetics and the product composition in the water–alcohol solutions. 相似文献
4.
(C5H4
i-Pr)2Ni exhibits the highest catalytic activity in the dimerization of ethylene among the nickelocenes, (C5H4R)2Ni (R = H, Et,n-Pr,i-Pr, ori-Bu) and their analogs (C5H4R)Ni(C3H5) (R = H,i-Pr). The higher activity is accompanied by lower selectivity with respect to 1-butene and with higher yields of 1-hexene. It is suggested that the introduction of an alkyl substituent in the cyclopentadienyl ring of nickelocene favors the generation of hydride sites involving the nickel atom. These sites participate in the process of ethylene dimerization.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 970–972, May, 1993. 相似文献
5.
Turevskaya E.P. Berdyev D.V. Turova N.Ya. 《Journal of Sol-Gel Science and Technology》1997,8(1-3):111-115
Complex formation in solutions of barium and zirconium alkoxides in ROH (R=i-Pr, Et) was studied. A number of bimetallic complexes were isolated, and their structure and properties were studied. The
sol-gel method yields a single-phase BaZrO3 powder only wheni-PrOH solutions of the alkoxides are used. In this case, the oxocomplex, BaZrO(OPr-i)4.(1–2)i-PrOH, is the precursor of the mixed oxide. 相似文献
6.
The adsorption parameters (α) established for the monosubstituted acetylenic liquids in this investigation are consistent with expectation based on analogies with the log αf = log αi ‐ Ds(Nf − Ni) relationships reported earlier for the many homologous series of liquids ZR, in which Z is a functional group having strong affinity for the pendent phenyl group of polystyrene and R is an alkyl substituent that is varied systematically. The order of relative Z‐affinities, based on α for the respective ZCH2CH3 molecules, confirm that the nature of Z is the major factor that affects α and that electronic and steric contributions from R are modifying effects, which are reflected in Ds. Comparisons of the results observed for HCC(CH2)nZ′ liquids with those for HCC(CH2)nH and with analogous pairs of Z(CH2)nZ′ series confirm that Z′ at the other end of the polymethylene chain can have a moderate positive effect or a marked negative effect on α, depending on whether the mode of adsorption to pendent phenyl groups is mono‐ or bidentate. This study also confirms that a sharp reversal in the roles played by the molecules participating in the adsorption process occurs when all of the hydrogen atoms covalently bonded to the center of unsaturation are replaced by alkyl substituents. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2611–2633, 1999 相似文献
7.
《Journal of organometallic chemistry》1986,299(1):29-40
The hydrogenation of (CF3)nGeX4-n (X = halogen, n = 1–3) with NaBH4 in an acidic medium has been investigated. Deuteration with NaBD4 and D3PO4 gave the partially deuterated species CF3GeHnD3-n and (CF3)2GeHnD2-n in reasonable isotopic purity. The (CF3)2GeHBr was isolated and converted into the halides (CF3)2GeHX (X = F, Cl, I) by treatment with AgX or HX. Insertion of CF2 into a GeH bond has been observed, and (CF3)(CF2H)GeH2 has been characterized. Direct alkylation of GeH bonds was brought about by reaction with a mixture of RI and R′2Zn (R, R′= CH3, C2H5), and the methyl(trif]uoromethyl)germanes CF3GeH2(CH3), CF3GeH(CH3)2 and (CF3)2GeH(CH3) were isolated. For R = CD3, R′ = CH3 the product distribution can be accounted in terms of two competing mechanisms. 相似文献
8.
Herbert Schumann Sebastian Dechert Frank Girgsdies Bernd Heymer Markus Hummert Ji‐Young Hyeon Jens Kaufmann Stefan Schutte Sonja Wernik Birgit C. Wassermann 《无机化学与普通化学杂志》2006,632(2):251-263
Synthesis and Characterization of New Intramolecularly Nitrogen‐stabilized Organoaluminium‐ and Organogallium Alkoxides The intramolecularly nitrogen stabilized organoaluminium alkoxides [Me2Al{μ‐O(CH2)3NMe2}]2 ( 1a ), Me2AlOC6H2(CH2NMe2)3‐2,4,6 ( 2a ), [(S)‐Me2Al{μ‐OCH2CH(i‐Pr)NH‐i‐Pr}]2 ( 3a ) and [(S)‐Me2Al{μ‐OCH2CH(i‐Pr)NHCH2Ph}]2 ( 4 ) are formed by reacting equimolar amounts of AlMe3 and Me2N(CH2)3OH, C6H2[(CH2NMe2)3‐2,4,6]OH, (S)‐i‐PrNHCH(i‐Pr)CH2OH, or (S)‐PhCH2NHCH(i‐Pr)CH2OH, respectively. An excess of AlMe3 reacts with Me2N(CH2)2OH, Me2N(CH2)3OH, C6H2[(CH2NMe2)3‐2,4,6]OH, and (S)‐i‐PrNHCH(i‐Pr)CH2OH producing the “pick‐a‐back” complexes [Me2AlO(CH2)2NMe2](AlMe3) ( 5 ), [Me2AlO(CH2)3NMe2](AlMe3) ( 1b ), [Me2AlOC6H2(CH2NMe2)3‐2,4,6](AlMe3)2 ( 2b ), and [(S)‐Me2AlOCH2CH(i‐Pr)NH‐i‐Pr](AlMe3) ( 3b ), respectively. The mixed alkyl‐ or alkenylchloroaluminium alkoxides [Me(Cl)Al{μ‐O(CH2)2NMe2}]2 ( 6 ) and [{CH2=C(CH3)}(Cl)Al{μ‐O(CH2)2NMe2}]2 ( 8 ) are to obtain from Me2AlCl and Me2N(CH2)2OH and from [Cl2Al{μ‐O(CH2)2NMe2}]2 ( 7 ) and CH2=C(CH3)MgBr, respectively. The analogous dimethylgallium alkoxides [Me2Ga{μ‐O(CH2)3NMe2}]2 ( 9 ), [(S)‐Me2Ga{μ‐OCH2CH(i‐Pr)NH‐i‐Pr}]n ( 10 ), [(S)‐Me2Ga{μ‐OCH2CH(i‐Pr)NHCH2Ph}]n ( 11 ), [(S)‐Me2Ga{μ‐OCH2CH(i‐Pr)N(Me)CH2Ph}]n ( 12 ) and [(S)‐Me2Ga{μ‐OCH2(C4H7NHCH2Ph)}]n ( 13 ) result from the equimolar reactions of GaMe3 with the corresponding alcohols. The new compounds were characterized by elemental analyses, 1H‐, 13C‐ and 27Al‐NMR spectroscopy, and mass spectrometry. Additionally, the structures of 1a , 1b , 2a , 2b , 3a , 5 , 6 and 8 were determined by single crystal X‐ray diffraction. 相似文献
9.
Free, unsolvated phenylium ions formed by the spontaneous β decay of a constituent atom of multitritiated benzene have been allowed to react with gaseous propene and cyclopropane in the pressure range from 10 to 700 torr. Phenylium ions attack efficiently both the C-H and the C-C bonds of cyclopropane, yielding respectively tritiated cyclopropylbenzene and indane as the major products. Selective attack of phenylium ions on the π bond of propene is suggested by the composition of tritiated products, isomeric phenylpropenes and isopropylbenzene. The different behavior of propene and cyclopropane toward gaseous phenylium ions is consistent with the results of related radiolytic investigations concerning gaseous systems at nearly atmospheric pressure. The reactivity pattern of the isomeric C3H6 hydrocarbons toward gaseous phenylium ions is discussed and compared with pertinent mass spectrometric data. 相似文献
10.
Coordination Polymer Flexibility Leads to Polymorphism and Enables a Crystalline Solid–Vapour Reaction: A Multi‐technique Mechanistic Study
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Dr. Iñigo J. Vitórica‐Yrezábal Dr. Stefano Libri Dr. Jason R. Loader Dr. Guillermo Mínguez Espallargas Dr. Michael Hippler Dr. Ashleigh J. Fletcher Dr. Stephen P. Thompson Dr. John E. Warren Prof. Daniele Musumeci Prof. Michael D. Ward Prof. Lee Brammer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8799-8811
Despite an absence of conventional porosity, the 1D coordination polymer [Ag4(O2C(CF2)2CF3)4(TMP)3] ( 1 ; TMP=tetramethylpyrazine) can absorb small alcohols from the vapour phase, which insert into Ag?O bonds to yield coordination polymers [Ag4(O2C(CF2)2CF3)4(TMP)3(ROH)2] ( 1‐ROH ; R=Me, Et, iPr). The reactions are reversible single‐crystal‐to‐single‐crystal transformations. Vapour‐solid equilibria have been examined by gas‐phase IR spectroscopy (K=5.68(9)×10?5 (MeOH), 9.5(3)×10?6 (EtOH), 6.14(5)×10?5 (iPrOH) at 295 K, 1 bar). Thermal analyses (TGA, DSC) have enabled quantitative comparison of two‐step reactions 1‐ROH → 1 → 2 , in which 2 is the 2D coordination polymer [Ag4(O2C(CF2)2CF3)4(TMP)2] formed by loss of TMP ligands exclusively from singly‐bridging sites. Four polymorphic forms of 1 ( 1‐ALT , 1‐AHT , 1‐BLT and 1‐BHT ; HT=high temperature, LT=low temperature) have been identified crystallographically. In situ powder X‐ray diffraction (PXRD) studies of the 1‐ROH → 1 → 2 transformations indicate the role of the HT polymorphs in these reactions. The structural relationship between polymorphs, involving changes in conformation of perfluoroalkyl chains and a change in orientation of entire polymers (A versus B forms), suggests a mechanism for the observed reactions and a pathway for guest transport within the fluorous layers. Consistent with this pathway, optical microscopy and AFM studies on single crystals of 1‐MeOH / 1‐AHT show that cracks parallel to the layers of interdigitated perfluoroalkyl chains develop during the MeOH release/uptake process. 相似文献
11.
Chelate Complexes LM/n of Transition Metals with Phosphinoimidic Amidato Ligands R2P(NR′)2– (= L) Reaction of LLi with metal halides or metal halide complexes affords chelate complexes LM/n (L = R2P(NR′)2–; M = Cr+++, Co++, Ni++, Zn++). With the bulky ligand t-Bu2P(NSiMe3)2– and Ni(PPh3)2Cl2 or Ni(dme)Br2 (dme = dimethoxyethane) only halide bridged chelates [LNiHal]2 (Hal = Cl, Br) containing tetrahedral chromophors NiN2Hal2 were obtained. Main objects of investigation were the bischelates L2Ni 2 . 2 a (R = i-Pr, R′ = Me) and 2 c (R = Ph, R′ = Et) are planar, 2 b (R = i-Pr, R′ = Et) and 2 d–g (R, R′ = i-Pr, i-Pr; Ph, i-Pr; Et, SiMe3; Ph, SiMe3) tetrahedral. In solutions of 2 b and 2 c a conformational equilibrium planar (diamagnetic) tetrahedral (paramagnetic) exists that is shifted to the right with increasing temperature and is dominated by the tetrahedral ( 2 b ) or planar conformer ( 2 c ) at room temperature. As is the case with the isovalence electronic compounds [R2P(S)NR′]2Ni small substituents R′ apparently favour the planar state and in contrast to some complexes [R2P(O)NR′]2Ni no paramagnetic planar species 2 have yet been observed. These findings that are derived from the results of magnetic measurements and of UV/VIS as well as NMR spectroscopy are confirmed by crystal structure determinations: 2 a was found to be planar (orthorhombic; a = 3382.8(11), b = 1124.0(4), c = 8874(3); P21212; Z = 6), and 2 g to be tetrahedral (monocline; a = 1268.4(2), b = 1806.8(2), c = 1971.6(2), P21/n; Z = 4). The bite angle NNiN of the chelate ligand in 2 a (ca. 77°) is similar to those in paramagnetic planar complexes [R2P(O)NR′]2Ni (NNiO 74–77°) and shows that a small chelate bite does not necessarily imply paramagnetism of planar Ni(II) complexes. 相似文献
12.
Chung‐Cheng Chang Kuo‐Ching Yang Jeng‐Gong Guo Leigh‐May Huang Li‐Chyung Wang Gene‐Hsiang Lee Shie‐Ming Peng 《中国化学会会志》2003,50(5):965-971
The insertion reaction of CS2 with Mg(NR2)2 (R= Et, iPr), MgR′2 (R′= Et, Ph) and R″MgBr (R″= iPr, Ph) respectively lead solid products, Mg(S2CNR2)2(THF)n ( 1 : R= Et, n=2; 2 : R= iPr, n=1), Mg(S2C′R)2(THF)2 ( 3 : ′R= Et, 4 : ′R= Ph), BrMg(S2C″R) (THF)3 ( 5 : ″R= iPr, 6 : ″R= Ph) in which the inserted carbon disulfides act as terminal chelating ligands. These compounds were characterized with 1H, 13C NMR, IR spectroscopy, mass spectrometry, elemental analyses, and X‐ray crystallography. 相似文献
13.
V. M. Jarvis M. A. Villanueva D. E. Bostwick T. F. Moran 《Journal of mass spectrometry : JMS》1993,28(5):595-606
Cluster ions from fast atom bombardment of liquid alcohols and nitriles were examined using a continuous-flow technique. Protonated molecular MnH+ species are the dominant cluster ions observed in molecules of formula M. The abundances of the MnH+ cluster ions decrease monotonically with increasing n, and within a homologous series the MnH+ abundance diminishes more rapidly for higher molecular mass compounds. Reaction products (ROH)n(H2O)H+ and (ROH)n(ROR)H+ are observed also in the case of alcohols, and the ion abundances decrease with increasing n. Radiation damage yields fragment ions and ionic alkyl reaction products which are captured in solvent clusters. Semi-empirical molecular orbital methods were used to examine the energetics of cluster ion formation and decomposition pathways. Metastable decomposition processes exhibit only evaporative loss of monomers, with the probability of loss increasing sharply with n. The evaporative ensemble model of Klots was used to predict the cluster size-dependent trends of metastable dissociation processes observed for alcohol and nitrile cluster ions. 相似文献
14.
Marc Gongoll Bernd H. Müller Stephan Peitz Bhaskar R. Aluri Normen Peulecke Anke Spannenberg 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):1845-1854
Abstract On the basis of the known aminodiphosphinoamine ligand Ph2PN(i-Pr)P(Ph) N(i-Pr)-H (3a), differently substituted aminodiphosphinoamine PNPN-H ligands (3) were prepared. By using different synthetic methods, the N-substituted ligands Ph2PN (i-Pr)P(Ph)N(c-Hex)-H (3b), Ph2PN(c-Hex)P(Ph)N(i-Pr)-H (3g), and Ph2PN(i-Pr)P(Ph) N[(CH2)3Si(OEt)3]-H (3c), in addition to the formerly described Ph2PN(n-Hex)P (Ph)N (i-Pr)-H (3h), Ph2PN(i-Pr)P(Ph)N(Et)-H (3d), Ph2PN(i-Pr)P(Ph)N(Me)-H (3e), and Ph2PN(c-Hex)P(Ph)N(c-Hex)-H (3f), were obtained. In addition, Ph2PN(i-Pr)P(Me)N(i-Pr)-H (3i), (cyclopentyl)2PN(i-Pr)P(Ph)N(i-Pr)-H (3j), (-O-CH2-CH2-O-)PN(i-Pr)P(Ph)N(i-Pr)-H (3k), and (1-Ad)2PN(i-Pr)P(Ph)N(i-Pr)-H (3l) were prepared with different P-substitutions. All compounds were characterized and the molecular structures of the intermediates Ph2PN(i-Pr)P(Ph)Cl (1a) and (cyclopentyl)2PN(i-Pr)P(Ph)Cl (1e) and the ligand (1-Ad)2PN(i-Pr)P(Ph)N(i-Pr)-H (3l) were investigated by single-crystal X-ray diffraction. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
15.
Several lanthanide chelates of the fluorochloroalkyl β-diketones Ln(CF2ClCOCHCOR)3 ·nH2O were prepared (2, Ln=Eu; 2a, R=C(CH3)3, n=0; 2b, R=C6F5, n=0; 2c, R=CF2Cl, n=2. 3, Ln=Pr; 3a, R=C (CH3)3, n=0; 3b, R=C6F5, n=l; 3c, R=CF2Cl, n=2. 4, Ln=La, R=C6H5, n=0) and the NMR shift data of compounds 2 and 3 had been determined using alcohols, ether, ketones and amine as substrates. With alcohol, ether and ketone, compounds 2 induces shifts similar to that induced by Eu (fod)3. However due to the high solubility of the chelates in non-polar organic solvents such as CHCl3 and CCl4 and the absence of 1H signal from compounds 2b and 2c, their application as a series of new 1H NMR shift reagents seems promising. 相似文献
16.
In Arbuzov-type reactions CFnCl3?nSCl reacts with ROPCl2 (R = CH3, C2H5) to give CFnCl3?nSP(O)Cl2 (n = 3,2,1,0). The corresponding reaction with CF3SeX (X = Cl, Br) produces CF3SeP(O)Cl2 in good yields only in the presence of catalysts such as SbCl5 or BCl3. Reactions between P4 and the sulfenylchlorides produce (CFnCl3?nS)xPCl3?n (n = 3,2,1 and x = 1,2). On heating CFn′ Cl3?n′ SP(O)Cl2 (n′ = 2,1,0) decompose to P(O)Cl3 and SCFn′ Cl2?n′. During this process fluorination of P(O)Cl3 to P(O)F3 by SCF2 is observed. A Cl/Br exchange between CFnCl3?nSP(O)Cl2 (n = 3,2) and PBr3 was proved 19F? and 31P-NMR-spectroscopically.Chemical and physical properties of the newly synthesized compounds will be discussed. 相似文献
17.
Erich Kleinpeter Matthias Heydenreich Andreas Koch Torsten Linker 《Tetrahedron》2012,68(10):2363-2373
The esters of 4-hydroxy-cyclohexanone and a series of carboxylic acids R–COOH with R of different electronic and steric influence (R=Me, Et, n-Pr, i-Pr, n-Bu, i-Bu, sec-Bu, t-Bu, CF3, CH2Cl, CHCl2, CCl3, CH2Br, CHBr2, and CBr3) were synthesized and the conformational equilibria studied by 1H and 13C NMR spectroscopy at 103 K and at 295 K, respectively. The geometry of optimized structures of the axial/equatorial chair conformers was computed at the ab initio MO and DFT levels of theory. Only one preferred conformation was obtained for the axial and the equatorial conformer as well. When comparing the conformational equilibria of the cyclohexanone esters with those of the corresponding cyclohexyl esters a certain polarity contribution of the cyclohexanone framework was revealed, which is independent of the substituent effects and increases the stability of the axial conformers by a constant amount. 相似文献
18.
Addition of one equivalent of LiN(i-Pr)2 or LiN(CH2)5 to carbodiimides, RN=C=NR [R=cyclohexyl (Cy), isopropyl (i-Pr)], generated the corresponding lithium of tetrasubstituted guanidinates {Li[RNC(N R^′2)NR](THF)}2 [R=i-Pr, N R^′2=N(i-Pr)2 (1), N(CH2)5 (2); R=Cy, N R^′2=N(i-Pr)2 (3), N(CH2)5 (4)]. Treatment of ZrCl4 with freshly prepared solutions of their lithium guanidinates provided a series of bis(guanidinate) complexes of Zr with the general formula Zr[RNC(N R^′2)NR]2Cl2 [R=i-Pr, N R^′2=N(i-Pr)2 (5), N(CH2)5 (6); R=Cy, N R^′2=N(i-Pr)2 (7), N(CH2)5 (8)]. Complexes 1, 2, 5-8 were characterized by elemental analysis, IR and ^1H NMR spectra. The molecular structures of complexes 1, 7 and 8 were further determined by X-ray diffraction studies. 相似文献
19.
Phosphinophosphiniden-Phosphorane tBu2P?P = P(R)tBu2 aus Li(THF)2[η2-(tBu2P)2P] und Alkylhalogeniden
The Phosphinophosphinidene-phosphoranes tBu2P? P = P(R)tBu2 from Li(THF)2[η2-(tBu2P)2P] and Alkyl Halides We report the formation of tBu2P? P = P(R)tBu2 a and (tBu2)2PR b (with R = Me, Et, nPr, iPr, nBu, PhCH2, H2C = CH? CH2 and CF3) reactions of Li(THF)2[η2-(tBu2P)2P] 2 with MeCl, MeI, EtCl, EtBr, nPrCl, nPrBr, iPrCl, nBuBr, PhCH2Cl, H2C = CH? CH2Cl or CF3Br. In THF solutions the ylidic compounds a predominate, whereas in pentane the corresponding triphosphanes b are preferrably formed. With ClCH2? CH = CH2 only b is produced; CF3Br however yields both tBu2P? P = P(Br)tBu2 and tBu2P? P = P(CF3)tBu2, but no b . The ratio of a:b is influenced by the reaction temperature, too. The compounds tBu2P? P = P(Et)tBu2 4a and (tBu2P)2PEt 4 b , e. g., are produced in a ratio of 4:3 at ?70°C in THF, and 1:1 at 20°C; whereas 1:1 is obtained at ?70°C in pentane, and 1:2 at 20°C. Neither tBuCl nor H2C = CHCl react with 2 . The compounds a decompose thermally or under UV irradiation forming tBu2PR and the cyclophosphanes (tBu2P)nPn. 相似文献
20.
Piero Nannelli H. D. Gillman 《Journal of polymer science. Part A, Polymer chemistry》1974,12(1):221-229
A series of polymers, {Cr(OH)(OPRR′O)[OOC(CF2)nCF(CF3)2]}x has been prepared and studied. The polymers with R = R′ = C6H5 are soluble in CCl2FCClF2, whereas those with R = CH3 and R′ = C6H5 and with R = R′ = C8H17 are insoluble in all solvents. Attempts to prepare similar materials without hydroxyl groups gave the polymers {Cr(OH)r(OPRR′O)p[OOC(CF2)nCF(CF3)2]q}x with 0 < r < 1. The latter polymers are much more tractable than the former; however they are also less thermally stable. The perfluoro-carboxylate groups in these materials can either be chelating or bridging, depending on the other ligands present. 相似文献