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Effect of thermal history on scratch performance of acrylonitrile styrene acrylate (ASA) and acrylonitrile butadiene styrene (ABS) model systems was studied. ASAs with rubber particle sizes of 100 nm and 1 µm, respectively, and ABS with rubber particle size of 100 nm were investigated. Linearly increasing normal load scratch tests were performed according to the ASTM-D7027/ISO-19252 standard. An improvement in scratch resistance is observed in ASAs when annealed at 140 °C whereas a noticeable drop in scratch resistance is found in ABS under the same condition. Various microscopic analyses were conducted to determine the corresponding deformation mechanisms for the observed dependence of scratch performance on annealing. Implication of the present findings for design of scratch resistant rubber toughened polymers is discussed.

Effects of rubber particle size and type on scratch performance were investigated using two types of styrenic copolymers: acrylonitrile styrene acrylate (ASA) and acrylonitrile butadiene styrene (ABS). ASAs with rubber particle sizes of 100 nm and 1 μm, respectively, and ABS with rubber particle size of 100 nm were examined. Linearly increasing normal load scratch tests were performed according to the ASTM D7027/ISO 19252 standard. A noticeable drop in scratch resistance is found in ASA with 100 nm rubber particles when compared to ASA containing 1 μm rubber particles. ABS is observed to exhibit a higher scratch resistance when compared to ASA with comparable rubber particle size. Detailed deformation and damage mechanisms have been investigated to explain the observed differences in scratch performance of the model systems. Implication of the present findings for design of scratch resistant polymers is discussed.

In order to predict scratch performance of polymers, the present study focuses on quantitative assessment of various scratch-induced deformation mechanisms based on a set of model amorphous polymers via numerical modeling. A modification of Ree-Eyring theory is used to account for the rate dependent behavior of the model polymers at high strain rates using the experimental data obtained at low strain rates. By incorporating the rate and pressure dependent constitutive and frictional behaviors in the finite element methods (FEM) model, good agreement has been found between FEM simulation and experimental observations. The results suggest that, by including appropriate constitutive relationship and frictional model in the numerical analysis, the scratch behavior of polymers can be quantitatively predicted with reasonable success. Usefulness of the present numerical modeling for designing scratch resistant polymers is discussed.

Surface friction plays an important role in influencing the stress field development during scratch process, thus, scratch-induced deformation mechanisms. In this study, three-dimensional finite element method (FEM) parametric study was performed along with experimental validation to investigate the effect of surface friction on scratch-induced deformation and its correlation with the constitutive behavior of polymers. As scratch depth and shoulder height are the key parameters for causing scratch visibility, the focus is to investigate the effect of surface friction on these two scratch-induced deformation features and how the surface friction effect can be altered by varying the constitutive parameters. The FEM findings and experimental observations indicate that onset of groove formation during the scratch process is strongly influenced by yield stress and coefficient of surface friction. Also, the relative frictional effect on scratch-induced deformation becomes minimal if the post-yielding strain hardening slope of the polymer is high. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Numerical modeling and experimental work were performed to establish a correlation between the bulk mechanical properties and scratch-induced deformation features in polymers. Three-dimensional finite element method (FEM) parametric study was carried out to investigate the effect of asymmetric tension–compression constitutive behavior on scratch-induced deformation of polymers. The scratch depth and shoulder height of the groove formed during the scratch was analyzed by considering different hypothetical asymmetric tension–compression constitutive behaviors. Experimental work on a set of model polymers was also carried out to validate the FEM findings following the ASTM D7027-05 scratch testing protocol. The results indicate that the compressive behavior, not the tensile behavior, dominates the scratch depth and shoulder height formation. Implication of the present findings for designing scratch resistant polymers is discussed.

The scratch behavior of butyl-acrylate rubber-modified styrene-acrylonitrile thermoplastics is investigated following the ASTM D7027 linearly increasing normal load test methodology. The critical normal loads at the onset of the major transitions along the scratch path, such as groove formation, scratch visibility, microcrack formation, and plowing, are reported and quantitatively analyzed. It is found that the scratch resistance generally deteriorates with increasing butyl-acrylate rubber content, and is strongly related to the tensile and compressive yield stresses of the blends. Microscopy investigation indicates that a rubber content of up to 30 wt % in a styrene-acrylonitrile copolymer (SAN) does not alter the scratch-induced damage mechanisms, but only reduces the critical onset loads for the observed damage transitions. The present finding suggests that addition of rubber causes reductions in modulus, tensile, and compressive yield stresses, thus leading to deterioration in scratch resistance. It appears that the improvement in ductility for SAN after the rubber toughening does not benefit scratch resistance. Implication of rubber toughening on scratch behavior of polymers is discussed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The scratch behavior of butyl-acrylate rubber-modified styrene-acrylonitrile (ASA) upon high temperature annealing is investigated following the ASTM D7027/ISO 19252 linearly increasing normal load test methodology. The critical normal loads at the onset of the major deformation transitions along the scratch path, such as groove formation, scratch visibility, microcrack formation, and plowing, are reported and quantitatively analyzed. It is found that the scratch resistance improves with high temperature annealing, i.e., 30 °C above T g , as compared to annealing below or around T g . Microscopic investigation suggests that the increase in scratch resistance is related to the changes in surface morphology of the polymer. It is concluded that performing high temperature annealing enhances the scratch performance without compromising ASA bulk properties. Implication of the present study for improving scratch resistance of polymers is discussed.

The effect of exposure to a humid environment on the scratch behavior of a set of model polystyrene–acrylonitrile (SAN) random copolymers was investigated over a period of 10 days. Linear increasing load scratch tests were performed according to ASTM D7027/ISO 19252. The critical loads for the onset of key scratch deformation mechanisms like periodic micro-cracking, plowing, and scratch visibility were used as metrics for evaluating scratch resistance. The scratching coefficient of friction was evaluated, as well. It was found that, in general, the scratch resistance decreases during the first few days of moisture exposure, but then experiences a degree of recovery upon saturation. It is proposed that the initially absorbed moisture causes plasticization, making the surface weaker until saturation where the water molecules gather together on the surface to impart a degree of lubrication and consequently improve the scratch resistance. Implications of moisture absorption on the scratch behavior of polymers will be discussed.

Fundamental understanding of the scratch behavior of styrene-acrylonitrile (SAN) random copolymers with variation in acrylonitrile (AN) content and molecular weight (MW) is pursued using the methodology outlined in ASTM D7027-05/ISO 19252:08. Two sets of SAN model systems are employed: One that varies the AN content with similar MW and another that varies the MW at the same AN content. Key scratch damage mechanisms (scratch groove formation, periodic micro-cracking, and plowing) are identified and correlated with the compressive and tensile properties of the SAN systems. Scratch visibility is analyzed through the use of a commercial software package. A fundamental structure–property relationship of SAN scratch behavior is proposed by the fact that increasing the AN content or the MW can have a positive effect on increasing the scratch resistance of SAN as it improves its tensile strength and ductility. The implication of material properties and their effect on polymer scratch behavior is discussed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Sulfurtrioxide reacts with the superacidic solutions XF/SbF 5 (X=H, D) to form the corresponding salts [X 2 SO 3 F] + [SbF 6 ] - , which are the protonated forms of fluorosulfuric acid. The salts have been characterized by vibrational spectroscopy and a single-crystal structure analysis. [H 2 SO 3 F] + [SbF 6 ] - crystallizes in the monoclinic space group P2 1 /n (no. 14) with four formula units in the unit cell. The crystal structure possesses a distorted tetrahedral 0 3 SF skeleton of the cations, which are linked with two strong hydrogen bridges to [SbF 6 ] - anions and forms a one-dimensional chain. The crystal structure and the vibrational spectra are compared to the quantum-chemical-calculated free [H 2 SO 3 F] + cation. Additionally, an [H 2 SO 3 F(HF) 2 ] + unit was calculated at the RHF/6-311++G(d,p) level to simulate H···F hydrogen bridges found in the solid state.

A new photolabile backbone amide handle has been developed for the synthesis of a melanocortin subtype-4 receptor (MCR4) agonist library in the solid phase. This traceless linker allows for the solid-supported synthesis of internal amides and their release under very mild, orthogonal conditions from solid support. The chemistry to attach an amide onto the linker is discussed. Structural variations of the linker in order to facilitate the attachment are investigated. The cleavage rate on the solid phase was measured. Finally, a small arylpiperazine library towards the MCR4 receptor was synthesized and its members characterized via HPLC, MS and NMR.

The gas phase structure of O-nitrobis(trifluoromethyl)hydroxylamine, (CF(3))(2)NONO(2), has been determined with gas electron diffraction and quantum chemical calculations (HF, MP2, and B3LYP with 6-31G basis sets). The calculations predict a structure with C(s) overall symmetry, a planar NONO(2) skeleton, and the NO(2) group oriented anti with respect to the CNC plane. The electron diffraction intensities are reproduced very well with such a model. The molecule possesses pyramidal configuration at the amino nitrogen atom, and the following geometric parameters (r(a) values with 3sigma uncertainties) were obtained for the NONO(2) skeleton: N-O = 1.392(18) A, O-N = 1.597(16) A, (N=O)(mean) = 1.192(4) A, N-O-N = 106.9(25) degrees, O=N=O = 138.4(24) degrees. The extremely long O-N distance is rationalized by very weak bonding between the two stable radicals (CF(3))(2)NO and NO(2). Whereas the ab initio methods HF (O-N = 1.395 A) and MP2 (O-N = 1.664 A) fail to reproduce this bond length correctly, the hybrid method B3LYP (O-N = 1.584 A) results in good agreement.

Die neuartige Imidazoliophosphonsaure Im—PO3H (7, Im = 2-{1, 3-diisopropyl-4, 5-dimethylimidazolio}) wird durch Hydrolyse des Phosphonylchlorids [Im-P(O)Cl2]Cl (6), das durch direkte Umsetzung des stabilen 2, 3-dihydro-1, 3-diisopropyl-4, 5-dimethylimidazol-2-ylidens (5) mit P(O)Cl3 zuganglich ist, erhalten. Die neuartige kationische Sulfonsaure [Im—SO3H]X ist als BF4- bzw. SbF6-Salz (11a, b) durch Umsetzung des Betains Im—SO3 (10) mit HBF4· Et2O bzw. HF/SbF5 zuganglich. Die Kristallstrukturen von 7 und 11b werden ermittelt und diskutiert. Novel Elementorganic Oxo-Acids of Phosphorus and Sulfur [1] The novel imidazoliophosphonate acid Im—PO3H (7, Im = 2-{1, 3-diisopropyl-4, 5-dimethylimidazolio}) is prepared through hydrolysis of the phosphonyl chloride [Im—P(O)Cl2]Cl (6) formed by the direct reaction of the stable 2, 3-dihydro-1, 3-diisopropyl-4, 5-dimethylimidazol-2-ylidene (5) with P(O)Cl3. The novel cat ionic sulfonic acid [Im—SO3H]X (11) is formed as its BF4 (11a) and SbF6 (11b) salt on treatment of the betaine Im—SO3 (10) with HBF4· Et2O or HF/SbF5. The crystal structures of 7 and 11b are reported and discussed.

The reaction of tribromophosphine oxide in the superacidic systems XF/MF(5) (X = H, D; M = As, Sb) leads to tribromohydroxyphosphonium hexafluorometalates. The structure was successfully elucidated in the case of tribromohydroxyphosphonium hexafluoroarsenate. Br(3)POH(+)AsF(6)(-) crystallizes in the orthorhombic space group Pnma (No. 53 with a = 1292.5(1) pm, b = 871.6(1) pm, and c = 845.0(1) pm) with four formula units per cell. The Raman, IR, (1)H NMR, and (31)P NMR spectra of Br(3)POX(+)MF(6)(-) (X = H, D; M = As, Sb) are reported.

Protonation of trithiocarbonic acid H2CS3 in the superacidic system HF/MF5 (M = As, Sb) results in the generation and isolation of the extremely water-sensitive salts C(SX)3+MF6− (M = As, Sb; X = H, D). The slightly yellow salts decompose above 233 K with the formation of SX3+MF6− and CS2. These new salts are characterized by vibrational and NMR spectroscopy and C(SH)3+AsF6− by X-ray diffraction.

Die Kristall­ struktur von [CollH]2 [AsF6][As2F11] (Coll = 2,4,6-Trimethylpyridin) Collidinium and Imidazolium Salts of Fluorine-Containing Anions. The Crystal Structure of [CollH]2[AsF6][As2F11] (Coll = 2,4,6-Trimethylpyridine) From s-Collidine (1, Coll) and aqueous HF compounds of the composition Coll · n HF (n = 1 -2) are formed which are transformed to [CollH]+ [HF2]- (2) by sublimation. [CollH]2[AsF6][As2F] J (3) is obtained from 1 and the superacid system HF/AsF5. 2 reacts with 2,3-dihydro-l,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (4, Im) to give the imidazo­ lium salt [ImH]+ [HF2]- (5). Hydrogen bonds in the crystal structure of [CollH]2[AsF6][As2Fn ] (3) are discussed.

Dichloroiodate Tetraphenylphosphonium dichloroiodate(I) [PPh4] [ICl2] crystallises in the monoclinic system in the space group P2/n with a = 1025.7(1), b = 770.2(1), c = 1446.4(1) pm, ß = 90.11(1)° and two formula units per unit cell. The ICl2 - anion is symmetrical (C2v) and almost linear with I-Cl bond lengths of 257.1(2) pm and a bond angle of 178.10(6)°.

Tetraphenylphosphonium triiodotetrabromide [PPh4][I3Br4] is obtained by the reaction of tetraphenylphosphonium bromide with iodine monobromide. It is the first example of an iodine rich, seven-membered polybromide. [PPh4][I3Br4] crystallizes triclinic in the space group P1 with a = 10.947(1) A, b = 11.945(1) A, c = 12.896(1) A, alpha = 66.80(1) degrees, beta = 77.21(1) degrees, gamma = 85.73(1) degrees, and two formula units per unit cell. The final R indices [I4 sigma(I)] are R1 = 0.0362 and wR2 = 0.0944.

The reactions of CF3I(Cl)F and CF3IF2 with (CH3)3SiOCH3 lead to the novel iodine(III) compounds CF3I(Cl)OCH3 and CF3I(OCH3)2, respectively. The crystal structure of CF3I(Cl)OCH3 confirms that it is a ternary, trifluoromethyl-substituted iodine(III) derivative. CF3I(Cl)OCH3 crystallizes in the triclinic space group P1¯, with four formula units per unit cell with the dimensions a = 8.164(1), b = 8.802(1), c = 10.237(1) A and angles α = 97.10(1)°, β = 91.41(1)°, γ = 115.00(1)°. CF3I(OCH3)2 crystallizes in the monoclinic space group P21/n with four formula units per unit cell with a = 6.295(1), b = 15.607(1), c = 7.736(1) A, and β= 111.44(1)°. Both molecules have been additionally characterized by Raman, IR, and NMR spectroscopy and the experimental results are compared with quantum-mechanically calculated parameters.

Die Reaktion von Ameisensauremethylester in den supersauren Systemen XF/MF5 (X = H, D: M = As, Sb) fuhrt zu den Hydroxymethoxycarbenium-Hexafluorometallaten. Die hydrolyseempfindlichen und thermolabilen Salze werden schwingungs- und NMR-spektroskopisch charakterisiert. Sie sind unter inerten Bedingungen bei –20 °C wochenlang haltbar. HC(OCH3)(OH)+AsF6– kristallisiert in der monoklinen Raumgruppe P21/c (Nr. 14) mit den Gitterkonstanten a = 5,275(1) A, b = 11,059(1) A, c = 12,113(1) A und β = 96,64(1)° und vier Formeleinheiten in der Elementarzelle. Reactions of Formic Acid Methylester in the Super Acidic System XF/MF5 (X = H, D: M = As, Sb) and the Crystal Structure of HC(OH)(OCH3)+AsF6– The reaction of formic acid methyl ester in the superacidic system XF/MF5 (X = H, D: M = As, Sb) leads to the hydroxy methoxy carbenium hexafluorometallates. The very hydrolysable and thermo labile salts are characterized by vibrational and NMR spectroscopic methods. Under inert conditions they are stable at –20 °C for some weeks. HC(OCH3)(OH)+AsF6– crystallizes in the monoclinic space group P21/c (No. 14) with a = 5.275(1) A, b = 11.059(1) A, c = 12.113(1) A und β = 96.64(1)° and four formula units per cell.

Dithiocarbonic acid O,S-dimethyl ester reacts with the super acidic system HF/MF5 (M = As, Sb) to form (MeO)(MeS)CSX+MF6− (M = As, Sb; X = H, D). (MeO)(MeS)CSH+SbF6− crystallizes in the monoclinic space group P21/n (No. 14) with a = 8.634(2) A, b = 9.521(3)A, c = 12.509(4) A, β = 97.39 (2)° and 4 formula units per cell. The reaction of O,S-dimethyl dithiocarbonate with the super acidic systems XF/MF5 (X = H, D; M = As, Sb) is discussed with regard to the formation of the salts, and Raman, IR, 1H NMR, and 13C NMR spectra of (MeO)(MeS)CSX+MF6− (M = As, Sb; X = H, D) are reported.

Trifluoromethyliodine(III) bis-trifluoracetate [CF3I(OCOCF3)2] was obtained by reaction between CF3IF2 and (CH3)3SiOCOCF3 at -50 °C. It crystallises in the triclinic space group P1̄ with a = 520.8(1), b = 1042.9(1), c = 1087.5(1) pm, α = 65.22(0)°, β = 81.18(0)°, γ = 80.09(0)°, and two formula units per unit cell. The compound has also been characterised by its Raman and IR spectra.

The geometric structure of perfluoro-N,N-dimethylformamide, (CF3)2NC(O)F, has been determined by gas electron diffraction (GED) and quantum chemical calculations (HF, MP2, and B3LYP with 6-311G* ba...

Dimethyltrithiocarbonate reacts with the superacidic systems HF/MF(5) and DF/MF(5) (M = As, Sb) to form (MeS)(2)CSX(+)MF(6)(-) (X = H, D). With an excess of AsF(5) the reaction leads to (MeS)(2)CSX(+)As(2)F(11)(-) (X = H, D). The latter salt crystallizes in the monoclinic space group P2(1)/c (No. 14 with a = 7.687(1) Å, b = 21.327(6) Å, c = 8.704(1) Å, and beta = 91.99(1) degrees ) with four formula units per cell. The undecafluorodiarsenate anion contains an As-F-As bridge with two As-F bonds significantly longer than the nonbridging bonds and an As-F-As angle of 159.1(6) degrees. The Raman, IR, and (1)H, (75)As, (19)F, and (13)C NMR spectra of (MeS)(2)CSX(+)SbF(6)(-) and (MeS)(2)CSX(+)As(2)F(11)(-) (X = H, D) are reported.

The reactions of perfluoro-aza-propene CF 3 NCF 2 with an excess of oxygen difluoride OF 2 and the fluorination of bis(trifluoromethyl)-hydroxylamine (CF 3 ) 2 NOH are discussed. Additionally, we present density functional calculations (B3LYP/6-31G*) on bis(trifluoromethyl)-hypofluorite (CF 3 ) 2 NOF, which clearly show that this molecule is a model substance for the discussion of negative hyperconjugation.

(Trifluoromethyl)iodine dichloride (CF(3)ICl(2)) is synthesized by the reaction of (trifluoromethyl)iodine chloride fluoride (CF(3)I(Cl)F) with trimethylchlorosilane ((CH(3))(3)SiCl) at -40 degrees C. By using this route of preparation, in which CF(3)I(Cl)F undergoes a chlorine-fluorine exchange, CF(3)ICl(2) can be obtained in high purity and yield. CF(3)ICl(2) crystallizes in the orthorhombic space group Cmca with a = 6.990(1) Å, b = 7.985(1) Å, c = 21.177(1) Å, and eight formula units per unit cell. The final R indices [I2sigma(I)] are R(1) = 0.0341 and wR(2) = 0.0631. CF(3)ICl(2) is, in contrast to iodine trichloride (ICl(3)), monomeric, and its molecular structure is T-shaped with the CF(3) group in the equatorial position. The Raman, IR, and NMR spectra are also described.

Die Reaktion von Trimethylstiban in den supersauren Systemen XF/MF5 (M = As, Sb, X = H, D) fuhrt zu den Trimethylstibonium-Hexafluorometallaten. Die erhaltenen Salze werden durch Schwingungsspektroskopie und Rontgenstrukturanalyse charakterisiert. Bei der Zersetzung des Trimethylstibonium Hexafluoroantimonats in Schwefeldioxid bei Raumtemperatur erfolgt die Darstellung von Hexamethyldistibonium Bis(hexafluoroantimonat) als Schwefeldioxid-Addukt, welches durch Kristallstruktur und Schwingungsspektren belegt ist. Reactions of Trimethylstibine in the Superacidic Systems XF/MF5 (X = H, D; M = As, Sb), Crystal Structures of (CH3)3SbD+SbF6– and (CH3)3SbSb(CH3)32+(SbF6–)2 · SO2 The reaction of trimethylstibine in the superacidic systems XF/MF5 (M = As, Sb; X = H, D) leads to the trimethylstibonium hexafluorometallates. The resulting salts are characterised by vibrational spectroscopy and their crystal structures. Decomposition of trimethylstibonium hexafluoroantimonate in sulphur dioxide at room temperature ends in the formation of hexamethyldistibonium bis(hexafluoroantimonate) as a sulphur dioxide adduct, verified by its crystal structure and vibrational spectra.

Die Reaktion von Oxalsaure im supersauren System HF/SbF5 fuhrt je nach Reaktionstemperatur zu unterschiedlichen Ergebnissen. So erfolgt bei –75 °C Protonierung der Oxalsaure zu HO(O)CC(OH)+SbF6– (1), wahrend bei einer Temperaturerhohung auf –40 °C Salze der Zusammensetzung (HO)2CC(OH)22+(SbF6–)2 · 4 H2O (2) entstehen. Die Salze werden durch Schwingungsspektroskopie und Kristallstrukturanalysen charakterisiert. Reactions of Oxalic Acid in the Superacidic Systems HF/MF5 (M = As, Sb), Crystal Structures of HO(O)CC(OH)2+SbF6– and (HO)2CC(OH)22+(SbF6–)2 · 4 H2O The reaction of oxalic acid in the superacidic system HF/SbF5 leads dependent on the reaction temperature to different results. At –75 °C monoprotonation to HO(O)CC(OH)2+SbF6– (1) occurs, whereas at –40 °C a salt of the composition (HO)2CC(OH)22+(SbF6–)2 · 4 H2O (2) is formed. The salts are characterised by vibrational spectroscopy and their crystal structures.

The formation of hydrogen bonds to acetonitrile molecules lends stability to the hitherto unknown hydrogenoxonium hexachloroantimonate H3O+SbCl6 - . The structure of H3O+SbCl6 - · 2 CH3CN was determined on a single crystal. It crystallises in the orthorhombic space group Pmn2( 1) (Nr. 31) with Z = 2, a = 1 12,7( 1 ),b = 988,8( 1) and c = 1036,5( 1) pm.

We have studied the preparation and isolation of the halogenated alkylidene oxonium salts CH(3)OCHX(+)MF(6)(-) (X = Cl, F; M = As, Sb). Addition of dichloromethylmethylether at -78 degrees C to the superacidic media HF/MF(5) resulted in the formation of the chlorine compounds CH(3)OCHCl(+)MF(6)(-), whereas at -65 degrees C the fluorinated salts CH(3)OCHF(+)MF(6)(-) are formed by a chlorine/fluorine exchange. The salts are characterized by their low-temperature IR and Raman spectra. Additionally, the crystal structures of the hexafluoroantimonates are presented. The structures of the cations turned out to be different in some points. The salt CH(3)OCHF(+)SbF(6)(-) crystallizes in the monoclinic space group P2(1)/c with 4 molecules in the unit cell and a = 9.942(2), b = 7.454(2), and c = 10.297(3) Å; beta = 111.27(2) degrees. The salt CH(3)OCHCl(+)SbF(6)(-) crystallizes in the monoclinic space group P2(1)/c with 4 formula in the unit cell and a = 5.970(3), b = 12.019(5), and c = 10.994(5) Å; beta = 92.59(3) degrees.

Die Reaktion von Perfluoraceton (CF3)2CO mit OF2 im Verhaltnis 2 : 1, die nur unter CsF-Katalyse stattfindet, liefert Perfluor(isopropyl)trifluoracetylperoxid (CF3)2C(F)OOC(O)CF3, dessen Charakterisierung durch Schwingungs-, NMR- und Massenspektren erfolgt. Unter Verwendung von OF2 im Uberschus kann kein stabiles Produkt isoliert werden. Preparation and Spectroscopic Characterization of Perfluoro(isopropyl)-trifluoroacetylperoxide (CF3)2C(F)OOC(O)CF3 The reaction of perfluoroacetone (CF3)2CO with OF2 in a ratio 2 : 1 yields Perfluoro(isopropyl)-trifluoroacetylperoxide (CF3)2C(F)OOC(O)CF3. The reaction only occurs under CsF-catalysis. (CF3)2C(F)OOC(O)CF3 is characterized by vibrational, nmr and mass spectra. Using an excess of OF2 does not give any stable product.

Es werden die Reaktionen des Difluorcyanamins in den supersauren Systemen XF/MF5 (X = H, D; M = As, Sb) vorgestellt. Die Charakterisierung der dabei isolierten Iminiumsalze F2NC(F)NX2+MF6– erfolgt durch Schwingungs-, NMR- und Massenspektren. Die Struktur und die Schwingungsfrequenzen des F2NC(F)NX2+-Kations werden zusatzlich durch ab initio Berechnungen mit Hartree-Fock-(HF/6-31 + G*) und Moller-Plesset-Basissatzen (MP2/6-31 + G*) bestimmt. Preparation and Spectroscopic Characterization of the Difluoroaminofluoro-iminium-hexafluorometallates F2NC(F)NX2+MF6– (X = H, D; M = As, Sb) Difluorocyanamin, F2NCN, does not react with the superacids XF/MF5 (X = H, D; M = As, Sb) under formation of protonated nitrilium salts. At –78 °C iminium salts of the general form F2NC(F)NX2+MF6– are observed, which are characterized by vibrational and nmr spectroscopy. The structure and vibrational frequencies were computed ab initio at the Hartree-Fock (HF/6-31 + G*) and correlated Moller-Plesset (MP2/6-31 + G*) levels of theory.

The geometric structures of N,N-bis(trifluoromethyl)-O-(trimethysilyl)hydroxylamine, Me3SiON(CF3)2 (1), and of trimethylsilyl nitrate, Me3SiONO2 (2), have been determined by gas electron diffraction and quantum chemical calculations (HF/3-21G*, B3LYP/6-31G*). Both compounds possess Cs symmetry. In 1 the Si−O bond is oriented syn with respect to the nitrogen lone pair (anti with respect to the CNC bisector of the N(CF3)2 group). In 2 the Si−O bond is coplanar with the nitrate group. The following skeletal parameters (ra values with 3σ error limits) have been derived: for 1, Si−O 1.724(8) A, N−O 1.450(18) A, Si−O−N 113.4(19)°; for 2, Si−O 1.715(4) A, N−O 1.383(5) A, Si−O−N 120.1(9)°. The unusually long Si−O bonds in both compounds can be rationalized by the electron-withdrawing power of the N(CF3)2 and NO2 groups. This leads to a reduction of the polarity of the Si+−O- bond and to lengthening of these bonds. The siloxane 2 possesses an extremely short 1,4-nonbonded contact between silicon and the cis-stand...

Trifluoromethyl iodine difluoride (CF3IF2) is synthesized by the reaction of trifluoromethyl iodide (CF3I) with trifluoromethyl hypochlorite (CF3OCl) at 223 K. This is a new route of preparation, in which CF3I is fluorinated by CF3OCl in an addition−elimination reaction. CF3IF2 crystallizes in the tetragonal space group I42d with a = 8.509(1) A, c = 12.324(2) A, and eight formula units per unit cell. Its molecular structure is T-shaped with a disordered CF3 group. The Raman and IR spectra are described.

Keywords The low temperature preparation of the bistrimethylsilylester of carbonic acid is reported. The hydrolysable and thermolabile (Me3SiO)2CO has been characterized by vibrational and NMR spectroscopic methods. Under inert conditions the (Me3SiO)2CO is stable at 233 K for several weeks.

Protonated hydrogen peroxide is produced from the reaction of antimony pentafluoride with bis(trimethylsilyl)peroxide in the presence of hydrogen fluoride. Depending on the stoichiometry of the reaction mixture, the compounds H3 O2 SbF6 and H5 O4 SbF6 are formed, which are stable up to room temperature and have been characterized by X-ray crystallography. The structure of the H3 O2+ ion is shown on the right.

The reaction of Me3SiI with (Me3SiO)2P(O)H leads to tris(trimethylsiloxy)phosphonium iodide (Me3SiO)3PH+I- which has been characterized by vibrational and NMR spectroscopy.

A preparation of trimethylsilanol by hydrolysis of bis(trimethylsilyl)carbonate in diethylether at -20°C is reported. At -80°C, the crystals are monoclinic, space group P21/c, Z = 12 with cell dimensions a = 996.0(2) pm, b = 1730.2(3) pm, c = 1122.9(2) pm, β= 96,61(3)°. There are three independent Me3SiOH units with a slightly distorted tetrahedral C3SiO core structure.