ESR study of the CF/sub 3/xxxF radical in irradiated trifluoroacetamide single crystals
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Abstract:
ESR and deuteration studies of x-irradiated trifluroacetamide crystals at 77 /sup 0/K show that the CF/sub 3/(A) radical initially formed interacts with a fluorine nucleus on a neighboring molecule, resulting in an additional fluorine doublet of A/sub z/=10 G, A/sub y/< or =A/sub x/< or =1 G. This previously unobserved spectrum decays with time at 77 /sup 0/K and is irreversibly replaced by the ESR spectrum of CF/sub 3/(B) that is stable to 200 /sup 0/K. Based on an INDO calculation, the formation of CF/sub 3/(A) occurs when the crystallographic intermolecular FxxxCF/sub 3/ distance in the parent compound decreases from 3.77 to 2.4 A upon radical formation at 77 /sup 0/K. Following the formation of CF/sub 3/(A), the FxxxCF/sub 3/ distance increases with time or temperature to approximately 3.0 A.Keywords:
Fluorine
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Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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Center (category theory)
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Abstract Die OyOxidation von S 3 N; in MeCN‐Lösung liefert als Hauptprodukte S4N;, S4N5O", S3N3O′ und S3N3OQ, deren relative Ausb. eine Funktion der Strömungsgeschwindigkeit des 02 sind.
Molecular oxygen
Molecular nitrogen
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Gas-phase reactions of laser-ablated actinide metal and oxide ions, An{sup +} and AnO{sub 1,2}{sup +} (An = Th, U, Np, Pu, Am), with perfluorocarbons (C{sub 14}F{sub 24} and C{sub 3}F{sub 6}), 1,2-dichloroethane (C{sub 2}H{sub 4}Cl{sub 2}) and 1,2-dibromoethane (C{sub 2}H{sub 4}Br{sub 2}) were studied by laser ablation with prompt reaction and detection. A primary goal was to determine variations in reaction pathways within the region of the actinide series where a progression from d-block transition metal-like (e.g., Th{sup +}) to lanthanide-like (e.g., Am{sup +}) chemistry is manifested. The high stabilities of the actinide fluorides, AnF{sub x}{sup +} and AnOF{sub x}{sup +}, resulted in F-abstraction as the primary reaction channel with perfluorocarbons. The studied An exhibited discrepant proclivities towards F-abstraction which reflected variable oxidation state stabilities. Thus, Np produced Np{sup IV}F{sub 3}{sup +} and Np{sup V}OF{sub 2}{sup +} whereas oxidation of Am terminated at Am{sup III}F{sub 2}{sup +}. Reactions of An{sup +} with C{sub 2}H{sub 4}Cl{sub 2} produced exclusively AnCl{sub 1,2}{sup +} whereas reactions with C{sub 2}H{sub 4}Br{sub 2} produced both AnBr{sub 1,2}{sup +} and AnC{sub 2}H{sub 2}{sup +}. The distinctive appearance of dehydrobromination as a reaction pathway is interpreted in the context of organoactinide reaction mechanistics. Halogen abstraction reactions are of interest for assessing chemical manifestations of the changing oxidation behavior across the actinide series and may be of utility for post-ionization separation of actinides for purification or analysis. Also identified were directly ablated oxide cluster ions such as ThUO{sub 4}{sup +}, NpPuO{sub 3}{sup +} and U{sub 2}ThO{sub 7}{sup +} - their compositions and abundances are correlated with solid actinide oxide chemistry. (orig.)
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The magnetic susceptibility of NdCo{sub 1-x}Ga{sub x}O{sub 3} (x = 0, 0.1, 0.3, 0.5, 0.7, 0.8, 0.9, 1) has been measured at temperatures from 80 to 950 K. The effective magnetic moments ({mu}{sub eff}) due to the magnetic moments of the Co{sup 3+} and Nd{sup 3+} ions have been determined in the temperature ranges of Curie-Weiss behavior, 130-370 and 600-940 K, and have then been used, together with the effective magnetic moment of Nd{sup 3+} (3.62 {mu}{sub B} or 4.20 {mu}{sub B}), to evaluate the effective magnetic moment of Co{sup 3+} in NdCo{sub 1-x}Ga{sub x}O{sub 3}. For the solid solutions with {mu}{sub eff} {sub Nd{sup 3+}} < 2.83 {mu}{sub B}, the fractions of intermediate- and low-spin Co{sup 3+} ions have been determined. In the range 2.83 {mu}{sub B} < {mu}{sub eff} {sub Co{sup 3+}} < 4.90 {mu}{sub B}, the fraction of high-spin Co{sup 3+} ions have been determined. The results indicate that, in the temperature range 130-370 K, the Co{sup 3+} ions in NdCo{sub 1-x}Ga{sub x}O{sub 3} with x = 0, 0.5, 0.8, and 0.9 are in the intermediate-and high-spin states, and the fraction of high-spin Co{sup 3+} ions gradually increases from 10% at x = 0 to 67% at x = 0.9. In the solid solutions with x = 0.1, 0.2, 0.3, and 0.7, more than half of the Co{sup 3+} ions are in the low-spin state, and the rest are in the intermediate-spin state. In the temperature range 600-940 K, the Nd{sup 3+} ions are in the ground and excited states, with theoretically predicted of {mu}{sub eff} {sub Nd{sup 3+}} of 3.62 {mu}{sub B} and 5.52 {mu}{sub B}, respectively. Because of the significant uncertainty in {mu}{sub eff} {sub Nd{sup 3+}} in this temperature range, {mu}{sub eff} {sub Co{sup 3+}} has been determined less accurately compared to the range 130-370 K.
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Propargyl
Crossed molecular beam
Reaction dynamics
Carbon fibers
Chemical reaction kinetics
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Abstract Die Isolierung des tetraedrischen Titelanions gelingt als N(PPh 3 ) 2 ‐ und Bu 4 N‐Salz aus der 2:1‐molaren Umsetzung entsprechender Chloride mit BZHÖ in Dichlormethan bei ‐78°C. Die Charakterisierung von [N(PPh3)2][BH3Cl] ‐ CH 2 Cl 2 erfolgt IR‐ und 1 H‐NMR‐spektroskopisch und durch eine Röntgenstrukturanalyse (RG PT, Z=2).
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