Cocatalysis by epoxides in the polymerization of tetrahydrofuran with trityl hexachloroantimonate initiator

The polymerization of tetrahydrofuran (THF) with (C₆H₅)₃C⁺SbCl₆^- initiator is markedly accelerated by small concentrations of propylene oxide or other epoxides. Molar concentrations of propylene oxide 4 to 10 times those of the carbonium-ion salt showed increasing conversion to polymer. The equilibrium conversion level at different temperatures with epoxides is the same as in their absence; the approach to equilibrium is first-order in THF. NMR experiments in the presence of propylene oxide indicate the formation of a trityl ether intermediate. The cocatalysis effect is interpreted on the basis of an acceleration in the initiation process in the system.     

Mechanism of Polymerization of 1, 3-Dioxolane Initiated by (C2H5)3 O+SbCl6 and SbCl5

The kinetics of polymerization of 1, 3-dioxolane (DiOX) initiated by (C₂H₅)₃O⁺SbCl₆ and SbCl₅ has been studied and the elementary stages of the process have been considered. The polymerization of DiOX by (C₂H₅)₃O⁺SbCl₆-is shown to proceed at a steady rate to high conversion. A constant concentration of active centers in the system is maintained due to the equal rates of decomposition of active centers and disproportionation. The nonsteady-state character of DiOX polymerization initiated by SbCl₅is associated with a relatively lower stability of the counter-ion SbCl₅ OR^? compared with SbCl₆. The initiation of DiOX polymerization by (C₂H₅)₃O⁺SbCl₆ proceeds without hydride-transfer reactions, and the concentration of active centers in the system is determined not by processes taking place in the initiation stage, but by the existence of a definite kind of equilibrium with the participation of active centers.     

Kinetics of Polymerization of 1,3-Dioxolan Initiated by C6H5COSbF,and (C6H5)3C+SbF8 Salts

Polymerizations of 1,3-dioxolan initiated by oxycarbenium salt CeHsCO⁺SbFe^? and triphenylmethylium salt (C6H₅)₃C⁺SbF₆ ^? proceed with induction periods. C₆H₅CO⁺SbF6 initiates polymerization by a direct addition, while initiation with (C₆H₅CO⁺SbFe^?proceeds through the intermediately formed 1,3-dioxolan-2-ylium salt. Kinetic analysis of polymerization of 1,3-dioxolan, initiated by oxycarbenium salt or triphenylmethylium salt revealed that, in spite of different chemisty of initiation, both processes proceed with a slow initiation on monomer and fast initiation on polymer. The pertinent kinetic equations were derived and it was found, that the rate constant of propagation (k) does not depend on the structure of initiator used, being equal to 25 ± 5 liter/mole-sec (0°C, CH₂Cl₂ or CH₃NO₂).     

Neue Alkylchlorsulfonium-Salze und Kristallstruktur von Diethylchlorsulfoni-umhexachloroantimonat (C2H5)2SCl+SbCl6−

New Alkylchlorosulfonium Salts and Crystal Structure of Diethylchlorosulfonium-Hexachloroantimonate (C₂H₅)₂SCl⁺SbCl₆^? We describe the preparation and spectroscopic characterization of Dialkylchlorosulfonium-Hexachloroantimonates R₂SCl⁺SbCl₆^? (R = C₂H₅, i-C₃H₇) and the crystal structure of Diethylchlorosulfonium-Hexachloroantimonate (C₂H₅)₂SCl⁺SbCl₆^? at 172(1) K. The salt crystallize in the orthorhombic space group P2₁2₁2₁ with a = 980.4(13) pm, b = 1010.6(8) pm, c = 1492.8(14) pm with four formula units per unit cell.     

Cationic Copolymerization of Propylene Oxide with Tetrahydrofuran. XI. Calculation of Individual Rate Constants

Rate constants (k₁ k₁₁, k₁₂, k₂₂, k₂₁ and k_t) for various steps involved in the copolymerization of propylene oxide (PO) with tetrahydrofuran (THF) have been calculated from reaction rate data obtained with the following catalyst system: (a) triphenyl-methyl cations ((C₆H₅)₃C⁺) associated with hexafluorophosphate (PF₆ ^?), hexafluoroarsenate (AsF₆ ^?) and hexafluoroantimonate (SbF₆ ^?) gegenions; (b) antimony pentachloride (SbCl₅); and, (c) boron trifluoride etherate, BF₃:(C₂H₅)₂O. The latter two systems were studied in the presence of cocatalysts. The effects of several parameters (the cocatalyst concentration and bulk size, the nature of the solvent, and the reaction temperature) on the rate constants are highlighted. The role of entropy in the initiation, propagation and termination steps is discussed in terms of solvation and desolvation processes. Based on termination activation energy considerations, the order of stability for the gegenions used in the copolymerization of PO with THF was found to be: AsF₆ ^? > SbF₆ ^? > HOBF₃ ^?PF₆ ^? > SbCl₆ ^?     

Über die Darstellung von Di(i-propyl)thiosulfonium-Salzen

On the Preparation of Di(i-propyl)thiosulfonium Salts [1] The preparation of the mercaptosulfonium salts (i-C₃H₇)₂SSX⁺SbCl₆^? (X = H, D) and of the chlorothiosulfonium salts (i-C₃H₇)₂SSCl⁺MF₆^? (M = As, Sb) and (i-C₃H₇)₂SSSCl⁺SbCl₆^? is reported. They are formed by reaction of chlorinated or protonated (i-C₃H₇)₂S with excess H₂S or SCl₂ and S₂Cl₂. The thiosulfonium compounds are characterized by vibrational and NMR spectroscopic methods.     

Über die Darstellung von Dimethyl(mercapto)sulfonium-hexa-chloroantimonat [(CH3)2SSH]+SbCl6−

Preparation of Dimethyl(mercapto)sulfonium-hexachloroantimonate [(CH₃)₂SSH]⁺SbCl₆^? The preparation of [(CH₃)₂SSH]⁺SbCl₆^? from [(Ch₃)₂SCl]⁺SbCl₆^? and H₂S at 223 K is reported. This salt is stable below 243 K and is characterized by vibrational spectroscopy.     

Die Kristallstruktur des 1 : 1-Adduktes zwischen Antimontrichlorid und Diphenylammoniumchlorid,SbCl3 · (C6H5)2NH2+Cl−

The Crystal Structure of the 1:1 Addition Compound between Antimony Trichloride and Diphenylammonium Chloride, SbCl₃ · (C₆H₅)₂NH₂⁺Cl^? The 1:1 addition compound between antimony trichloride and diphenylammoniumchloride SbCl₃ · (C₆H₅)₂NH₂⁺Cl^? crystallizes in the monoclinic space group P2₁/n with a = 5.668(8), b = 20.480(12), c = 14.448(17) Å, β = 110.4(1)° and Z = 4 formula units. Chains of SbCl₃ molecules and anion cation chains are bridged by Cl ions and form square tubes. The coordination of the Sb atoms by Cl atoms by Cl atoms and Cl ions is distorted octahedral. Mean distances are Sb? Cl = 2.37 Å for Sb? Cl (3×), 3.09 Å for Sb…Cl^? (2×) and 3.42 Å for Sb…Cl (1×). The Sb…Cl^? contacts and hydrogen bonds NH…Cl^? at 3.15 Å generate tetrahedral coordination of the Cl ions.     

Über die Darstellung der Trimercaptosulfoniumsalze [S(SH)3]+AsF6− und [S(SH)3]+SbCl6−

Preparation of Trimercaptosulfonium Salts [S(SH)₃]⁺AsF₆^? and [S(SH)₃]⁺SbCl₆^? The preparation of the trimercaptosulfonium salts [S(SH)₃]⁺AsF₆^? and [S(SH)₃]⁺SbCl₆^? from SCl₃⁺ salts with excessive H₂S at 193 K is reported. The [S(SH)₃]⁺SbCl₆^? is transferred into [S(SCl)₃]⁺SbCl₆^? by reaction with Cl₂ at low temperatures. The new [S(SH)₃]⁺ cation is isoelectronic to P(PH₂)₃. In addition, its existence is supported by an ab-initio calculation. The results show a potential well for C_3v configuration with SH bonds bended towards the top of the pyramid for the isolated ion. Also the results of a force-field calculation are reported.     

Schwingungsspektroskopische Untersuchungen an Trimethylphosphonium-Kationen (CH3)3PX+ (X = H,D) und Kristallstrukturen von (CH3)3PD+SbCl6− und (CH3)3PCl+SbCl6−

Vibrational Spectra of Trimethylphosphonium Cations (CH₃)₃PX⁺ (X = H, D) and Crystal Structures of (CH₃)₃PD⁺SbCl₆^? and (CH₃)₃PCl⁺SbCl₆^? The trimethylphosphonium salts (CH₃)₃PX⁺SbCl₆^? (X = H, D) and (CH₃)₃PH⁺MF₆^? (M = As, Sb) are prepared and characterized by vibrational and NMR spectroscopy (¹H, ³¹P, ¹³C). In addition the crystal structures of (CH₃)₃PD⁺SbCl₆^? and (CH₃)₃PCl⁺SbCl₆^? are reported. (CH₃)₃PD⁺SbCl₆^? crystallizes in the orthorhombic space group Pnma with a = 1555(1) pm, b = 753.1(8) pm, c = 1166(1) pm Z = 4. (CH₃)₃PCl⁺SbCl₆^? crystallizes triclinic in the space group P1 with a = 704.6(4) pm, b = 729.5(3) pm, c = 1391.1(7) pm, α = 89.57(4)°, b? = 88.04(4)°, γ = 74.98(4)° and Z = 2.     

Unexpected product formed by the reaction of [2,6-(MeOCH2)2C6H3]Li with SbCl3: Structure of Sb-O intramolecularly coordinated organoantimony cation

Reaction of [2,6-(MeOCH₂)₂C₆H₃]Li (1) with SbCl₃ in 1:1 molar ratio yielded except the intended product [2,6-(MeOCH₂)₂C₆H₃]SbCl₂ (2) unexpected complex 3 consisting of antimony anion [Sb₆Cl₂₂]⁴⁻ compensated by four intramolecularly coordinated organoantimony cations [2,6-(MeOCH₂)₂C₆H₃]₂Sb⁺. Compound 3 is labile in CH₂Cl₂(CHCl₃) solution and decomposes to compound 2 and SbCl₃. Both compounds were characterized by the help of ¹H and ¹³C NMR spectroscopy, ESI-mass spectrometry and in the case of 3 by single crystal X-ray diffraction techniques.     

On the interaction of triphenylmethyl salts with α-methylstyrene

The interaction of triphenylmethyl salts with α-methylstyrene and 1,1-diphenylethylene was investigated. With 1,1-diphenylethylene at a monomer-initiator ratio of 2 (room temperature), mainly 1,1,3-triphenyl-3-methyl-indane was isolated, whereas at a ratio of 100 (?10°C), the dimer 1,1,3,3-tetraphenylbutene-1 mainly formed. In both cases no addition of the trityl group was registered. In the interaction of α-methylstyrene with Ph₃C⁺SbCl at a monomer-initiator ratio of 2(room temperature) a pure 1,3,3-trimethyl-1-phenylindane was isolated and no addition of the trityl group to the double bond was recorded. The initiation reaction of α-methylstyrene polymerization by trityl and chlorinated trityl salts was studied at temperatures from ?20 to 0°C and different concentrations. The oligomers obtained with (pCI-C₆H₄)₃C⁺ were investigated by elemental analysis and fluorescence spectroscopy. The presence of Ph₃CH in the reaction mixture was demonstrated by GLC and NMR spectra. The results obtained give evidence that the initiation of α-methylstyrene polymerization involves hydride abstraction from the monomer.     

Univalent Gallium Complexes of Simple and ansa‐Arene Ligands: Effects on the Polymerization of Isobutylene

Using [Ga(C₆H₅F)₂]⁺[Al(OR^F)₄]^?( 1 ) (R^F=C(CF₃)₃) as starting material, we isolated bis‐ and tris‐η⁶‐coordinated gallium(I) arene complex salts of p‐xylene (1,4‐Me₂C₆H₄), hexamethylbenzene (C₆Me₆), diphenylethane (PhC₂H₄Ph), and m‐terphenyl (1,3‐Ph₂C₆H₄): [Ga(1,4‐Me₂C₆H₄)_2.5]⁺ ( 2⁺ ), [Ga(C₆Me₆)₂]⁺ ( 3⁺ ), [Ga(PhC₂H₄Ph)]⁺ ( 4⁺ ) and [(C₆H₅F)Ga(μ‐1,3‐Ph₂C₆H₄)₂Ga(C₆H₅F)]²⁺ ( 5²⁺ ). 4⁺ is the first structurally characterized ansa‐like bent sandwich chelate of univalent gallium and 5²⁺ the first binuclear gallium(I) complex without a Ga?Ga bond. Beyond confirming the structural findings by multinuclear NMR spectroscopic investigations and density functional calculations (RI‐BP86/SV(P) level), [Ga(PhC₂H₄Ph)]⁺[Al(OR^F)₄]^?( 4 ) and [(C₆H₅F)Ga(μ‐1,3‐Ph₂C₆H₄)₂Ga(C₆H₅F)]²⁺{[Al(OR^F)₄] ^?}₂ ( 5 ), featuring ansa‐arene ligands, were tested as catalysts for the synthesis of highly reactive polyisobutylene (HR‐PIB). In comparison to the recently published 1 and the [Ga(1,3,5‐Me₃C₆H₃)₂]⁺[Al(OR^F)₄]^? salt ( 6 ) (1,3,5‐Me₃C₆H₃=mesitylene), 4 and 5 gave slightly reduced reactivities. This allowed for favorably increased polymerization temperatures of up to +15 °C, while yielding HR‐PIB with high contents of terminal olefinic double bonds (α‐contents=84–93 %), low molecular weights (M_n=1000–3000 g mol^?1) and good monomer conversions (up to 83 % in two hours). While the chelate complexes delivered more favorable results than 1 and 6 , the reaction kinetics resembled and thus concurred with the recently proposed coordinative polymerization mechanism.     

Interaction of the Benzenium Ion with Inert Ligands: IR Spectra of C6H7+?Ln Cluster Cations (L=Ar,N2, CH4, H2O)

IR photodissociation spectra of mass‐selected clusters composed of protonated benzene (C₆H₇⁺) and several ligands L are analyzed in the range of the C? H stretch fundamentals. The investigated systems include C₆H₇⁺? Ar, C₆H₇⁺? (N₂)_n (n=1–4), C₆H₇⁺? (CH₄)_n (n=1–4), and C₆H₇⁺? H₂O. The complexes are produced in a supersonic plasma expansion using chemical ionization. The IR spectra display absorptions near 2800 and 3100 cm^?1, which are attributed to the aliphatic and aromatic C? H stretch vibrations, respectively, of the benzenium ion, that is, the σ complex of C₆H₇⁺. The C₆H₇⁺? (CH₄)_n clusters show additional C? H stretch bands of the CH₄ ligands. Both the frequencies and the relative intensities of the C₆H₇⁺ absorptions are nearly independent of the choice and number of ligands, suggesting that the benzenium ion in the detected C₆H₇⁺? L_n clusters is only weakly perturbed by the microsolvation process. Analysis of photofragmentation branching ratios yield estimated ligand binding energies of the order of 800 and 950 cm^?1 (≈9.5 and 11.5 kJ mol^?1) for N₂ and CH₄, respectively. The interpretation of the experimental data is supported by ab initio calculations for C₆H₇⁺? Ar and C₆H₇⁺? N₂ at the MP 2/6‐311 G(2df,2pd) level. Both the calculations and the spectra are consistent with weak intermolecular π bonds of Ar and N₂ to the C₆H₇⁺ ring. The astrophysical implications of the deduced IR spectrum of C₆H₇⁺ are briefly discussed.     

A calorimetric study of the interaction of H2O·SbCl5 and HCl-SbCl,with weak organic bases in 1,2-dichloroethane

The enthalpies of interaction between H₂O·SbCl₅ and the oxygen bases DMA, n-Pr₂O, MePrCO, and EtOAc to form ternary complexes D·H₂O-SbCl₅ in 1,2-dichloroethane solution have been determined calorimetrically. Reaction of water with the binary adducts D·SbCl₅;, result in the formation of the same ternary complexes which has been confirmed by PMR spectroscopic experiments. The base molecules are considered to be strongly H-bonded to the H₂O-SbCl₅ adduct in the complexes in solution.The enthalpy of formation of H₂O-SbCl₅ in 1,2-dichloroethane solution has been redetermined.The enthalpies of formation of the [DH]⁺SbCl^?₆ and [D₂H]+SbCl^?₆ complexes from the complex acid HCl-SbCl₅ and Pr₂O, MePrCO and (MeO)₂CO have been determined and estimates of the association constant for the formation of the [DH]⁺SbCl^?₆ complexes from the D·SbCl₅, adducts have been derived for D = MePrCO, EtOAc and (MeOP₂CO.Measurements of the interaction between HCl-SbCl₅ and the protogenic ligands PrOH and H₂O were also made.     

Reaktionsprodukte aus Chlormethoxiphosphinen und Antimon(V)-chlorid. Schwingungsspektren der 1:1 Addukte aus Methoxiphosphorylverbindungen und Antimon(V)-chlorid

Reaction Products of Chloromethoxiphosphines and Antimony (V) Chloride. Vibrational Spectra of the 1:1-adducts of Methoxiphosphoryl Compounds and Antimony (V) Chloride Chloromethoxiphosphines react with antimony(V) chloride in a redox process to yield the chloromethoxiphospllonium hexachloroantimonates(V) (CH₃O)₃PCl₂⁺SbCl₆^? (II) and CH₃OPCl₃⁺SbCl₆^? (III). II, III, (CH₃O)₃PCl⁺SbCl₆^?(1) and (CH₃O)₄P⁺SbCl₆^? eliminate easily methyl chloride and give the addition compounds OP(OCH₃)₃·SbCl₅(IV), OPCl(OCH₃)₂ · SbCl₅ (V), OPCl₂(OCH₃)·SbCl₅ (VI) and OPCl₃·SbCl₅ (VII). The vibrational spectra of IV, V nnd VI are discussed.     

Antimonypentafluoroorthotellurates: Sb(OTeF5)3, Sb(OTeF5)5 and salts of Sb(OTeF5)6−

Antimony(III)pentafluoroorthotellurate has been synthesized from SbF₃ and B(OTeF₅)₃. Contrary to a previous report it is a low melting, sublimable solid (mp = 28°, bp (0.1 torr) = 68°, ¹⁹F - NMR: AB₄ spinsystem δ (A) = ?42.7, δ (B) = ?38.1, J (AB) = 186 Hz). It reacts with F₂, Cl₂ and Br₂ to give SbF₂(OTeF₅)₃, SbCl₄⁺Sb(OTeF₅)₆^? and SbBr₄⁺ Sb(OTeF₅)₆^? respectively. Interaction of Xe(OTeF₅)₂ and Sb(OTeF₅)₃ yields Sb(OTeF₅)₅, which is unstable at room temperature. Salts containing the new anion Sb(OTeF₅)₆^? have been synthesized either from Sb(OTeF₅)₅ and a corresponding pentafluoroorthotellurate e.g. Sb(OTeF₅)₅ + NMe₄⁺ OTeF₅^? = NMe₄⁺ Sb(OTeF₅)₆^?, or from SbCl₄ Sb(OTeF₅)₆^? and an appropriate chloride SbCl₄⁺ Sb(OTeF₅)₆^? + NOCl = SbCl₅ + NO⁺ Sb(OTeF₅)₆^?, or oxidatively, using a mixture of Xe(OTeF₅)₂ and Sb(OTeF₅)₅, e.g. C₆F₆ + $\text{1}\text{2}$ Xe(OTeF₅)₂ + Sb(OTeF₅)₅ = C₆F₆⁺ Sb(OTeF₅)₆^? + $\text{1}\text{2}$ Xe.     

UHMWPE with short‐chain branches synthesized by alkenyl substituted phenoxy–imine catalysts in ethylene polymerization

The alkenyl substituted phenoxy–imine complexes [2‐C₃H₅‐6‐(2, 3, 5, 6‐C₆F₄H‐N?CH)C₆H₃O]₂TiCl₂ (C₃H₅=? CH₂? CH?CH₂ or ? CH?CH? CH₃) are synthesized and characterized by ¹H NMR, ¹³C NMR, and elemental analysis. When activated by MAO, they show high activity for the polymerization of ethylene to UHMWPE under different conditions (temperatures and polymerization time). Most of the resulting polymers have high molecular weights (>1.0 × 10⁶ g·mol^?1) and high melting points as well as crystallinity. To clarify the effect of the alkenyl group on the catalytic performance and the resultant polymer microstructure, the corresponding saturated complexes of type [2‐C₃H₇?6‐(2, 3, 5, 6‐C₆F₄H‐N?CH)C₆H₃O]₂TiCl₂ where C₃H₇ = –CH₂? CH₂? CH₃ or ? CH(CH₃)₂ were synthesized and tested as catalysts in ethylene polymerization under the same reaction conditions. The microstructure and morphologies of these two species of PE samples were fully compared by the analysis of ¹³C NMR, GPC, DSC, and SEM. As a result, the allyl substituted complex show the highest activity to prepare the highest molecular weight polyethylene of all the catalysts. An interesting feature of the UHMWPE produced by these four catalysts is that they contain only a few short‐chain branches (mainly methyl, isobutyl and 2‐methylhexyl branches) in a low amount (<2.7 branches/1000 C). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3808–3818     

Benzophenone‐(phenylthio)acetic acid phosphonium salts as initiators of free‐radical photopolymerization of vinyl monomers: Mechanistic studies

The mechanism of the benzophenone‐sensitized photooxidation of phosphonium salts of (phenylthio)acetic acid was studied as a means for understanding how these salts function as coinitiators in the free‐radical photopolymerization of vinyl monomers. Both steady‐state and nanosecond flash photolytic methods were used to determine, in a quantitative manner, the mechanism of primary and secondary photoreactions for three quaternary phosphonium salts containing butyl and/or phenyl groups, i.e., P⁺(C₄H₉)₄, P⁺(C₄H₉)(C₆H₅)₃, and P⁺(C₆H₅)₄. It was found that the initial polymerization rates were the same for all three phoshonium salts of (phenylthio)acetic acid and were equal to those found previously for tetralkyl ammonium salts. The polymerization rates were more than twice the rates found for direct initiation by benzophenone and by the benzophenone‐(phenylthio)acetic acid initiating system. These results correlate well with the large quantum yields of ^?CH₂SC₆H₅ radicals (the main initiating radicals) found in the complementary photochemical investigation. It was found that a detailed knowledge of the photochemical reactions in the photoinitiating systems was critical to understand the kinetics of polymerization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8013–8022, 2008     

Wasserstoffbrückenbindungen in zweikernigen μ-Hydroxobis[trichloroantimon(V)]-Komplexen mit Phosphatbzw. Phosphonatgruppen als überbrückende Liganden

Hydrogen Bonds in Binuclear μ-Hydroxo-bis[trichloroantimony(V)] Complexes with Phosphate or Phosphonate Groups as Bridging Ligands Benzylphosphonic acid monoalkylesters react with antimony(V) chloride and water to yield Cl₃SbO(OH)[(C₆H₅CH₂)RPO₂]SbCl₃ · H₂O ( 1 : R = OCH₃; 2 : R = OC₂H₅). With difluoro phosphoric acid only Cl₃SbO(OH)(F₂PO₂)SbCl₃ ( 3 ) can be isolated. The crystal and molecular structures of 1 to 3 were determined. 1 and 2 both crystallizing orthorhombic in the space group Pnma are hydroxonium salts H₃O⁺[Cl₃SbO₂((C₆H₅CH₂)RPO₂)SbCl₃]^–. Strong hydrogen bridges link cations and anions to chains. One of the hydrogen atoms of the cation makes a weak but important OH/π interaction to the para C atom of the benzyl group. In 3 (monoclinic, P2₁/n) the molecules are connected by hydrogen bridges to fourfold δ and helices λ. In solution there is a rapid intermolecular exchange of protons. IR and NMR data are communicated and briefly discussed.