Gabriele Schatte

Thermochemistry of octasulfur-bis-hexafluoroarsenate S8(AsF6)2 containing the lattice-stabilized S82+

Abstract The specific energy of combustion of S 8 (AsF 6 ) 2 in fluorine according to the reaction: S 8 (AsF 6 ) 2 (cr) + 23F 2 (g) = 8SF 6 (g) + 2AsF 2 (g) was measured calorimetrically to be − (14327±9) J · g −1 at T = 298.15 K and p o = 101.325 kPa, where the uncertainty is the standard deviation of the mean. From this result was calculated the standard molar enthalpy of formation Δ f H m o {S e (AsF 6 ) 2 , cr, 298.15 K} = −(3121.5 ± 11.7) kJ · mol −1 , where the uncertainty is twice the standard deviation of the mean. The significance of this value with respect to bonding in the title and related compounds is discussed. Thus, the lattice energy of S 8 (AsF 6 ) 2 was estimated to be (1517 ± 36) kJ · mol −1 , and it was shown that S 8 2+ in the gas phase was unstable with respect to dissociation into various S x + (g) cations (2 ⩽ x ⩽ 7), while S 8 2+ in the solid state was lattice stabilized in S 8 (AsF 6 ) 2 .

Die Wechselwirkung von N3F mit Lewis-Säuren und HF. N3F als möglicher Vorläufer für die Synthese von N3+-Salzen / The Interaction of N3F with Lewis-Acids and HF. N3F as Possible Precursor for the Synthesis of N3+ Salts

Triazadienyl fluoride, N3F, forms stable adducts with BF3 and AsF5 at low temperatures, as demonstrated by infrared measurements. The Lewis acids are bonded to the Nα-atom of N3F, as deduced from the data for 15N-isotopically enriched N3F. The basicity of N3F is comparable to that of ethine and ethene, according to the HF stretching frequency of the N3F/HF complex isolated in an argon matrix. Despite the low NF bond energy (< 150 kJ/mol), abstraction of the fluoride ion and formation of an N3+ salt was not possible. The different behavior of N3F and ClN3 towards Lewis acids is discussed.

An improved synthesis of SF5(CN) and its cycloaddition reaction with SNSAsF6. Crystal structure of F5SCNSNSAsF6 and electron spin resonance spectrum of F5SCNSNS

An improved synthesis of SF5(CN), by direct fluorination of SF3(CN), has been achieved. This product forms a stable adduct at low temperature with AsF5, and addition of MeCN to this adduct led to very pure SF5(CN). The SF5(CN)·AsF5 adduct has been characterized by vibrational and 19F Fourier-transform NMR spectroscopy and by its dissociation vapour-pressure curve. The salt SNSAsF6 and an excess of SF5(CN) reacted in sulfur dioxide solution to give the stable salt F5S[graphic omitted]AsF6 which has been characterized by vibrational, 19F NMR and mass spectroscopy and X-ray crystallography. The structure consists of discrete F5S[graphic omitted]+ cations and AsF6– anions. The mass spectrum of F5S[graphic omitted]AsF6 was consistent with loss of AsF5 and fluoride ion transfer to give F5S[graphic omitted] which dissociated to SF4 and F2[graphic omitted]. Reduction of a dilute solution of the salt in SO2 led to identification (ESR spectroscopy) of the radical F5S[graphic omitted]˙.

Solid-State and Solution FT-Raman Spectra of the Tetraiodine Dication I42+: Implications for the Claimed Existance of ‘T+’ in SO2Solution

Abstract I4 2+ is the only known cyclic homopolyatomic cation or anion of iodine. It has a rectangular planar structure which may be thought of as containing two I2 + units joined by a weak π∗-π∗ 4 centre 2 electron bond.1 In this paper we report our FT-Raman spectra of I4 2+, which conflict with those published by Gillespie et al. 1 and present evidence that the peaks attributed to a species containing iodine in the +1 oxidation state are in fact due to I4 2+.