Gas-phase IR spectroscopy

Difluoroethene (0.19 g. 3 mmol) was dissolved in CF3C1 (2 mL) at — 95 C. The alkcnc was ozonized to 100% completion using flow rates of 0.10-0.15 mL of 03 min" . Immediately after the completion of ozonolysis. the volatile material in the reactor was allowed to w arm and was lrap-to-trap distilled through - 140 and — 196 C traps. The contents of the — 196 C trap were examined by gas-phase IR spectroscopy and contained only CF3C1 and a small amount of unreacled o/one. SiF4 and HCOF. 

Sulfenic acid (3) has been synthesized in the gas phase by low-pressure, high-temperature pyrolysis of di-t-butyl sulfoxide (4) and characterized by means of matrix isolation and gas-phase IR spectroscopy (Scheme 4).32 The mechanism of formation of (3) by flash pyrolysis of (4) has been studied by quantum chemical calculations, and different pyrolysis experiments monitored by mass spectrometry. In agreement... 

Both compounds were identified by means of multinuclear NMR spectroscopy ( H, C, F) and gas-phase IR spectroscopy. F3SiN(SiMc3)NMe2 was further characterized by and Si NMR and by mass spectrometry. 

The thermal decomposition of 2 results in the formation of only two main products, which could be identified using IR spectroscopy, namely CO2 [94] and CO [95]. In addition trace amounts of HCN and CH4 were visible in the gas-phase IR spectrum, however, no evidence for the formation of water vapor was foimd. fii the methylated compounds, many more decomposition products were observed using gas-phase IR spectroscopy. Besides CO2 and CO, larger amounts of CH4 [96] and HCN were found in the decomposition of 5 and 6, in comparison with 2. In contrast to 5, where bigger amounts of expected NH3 were detected, the thermal decomposition of 6 shows only traces of NH3 but moderate amoimts of N2O [97]. 

In order to use variable-temperature gas-phase IR spectroscopy to investigate gas-phase equilibria, it is necessary to determine first the relative extinction coefficients for the two conformers once this has been done the quantitative analysis is straightforward. A van t Hoff plot [In(Ap) versus 7 ] can be drawn and this can then be used to extract the required thermodynamic data, i.e. the enthalpy difference between the two structures and the corresponding entropy terms. On this basis, the experimental data returned a value for of —6.92 0.05 kJ mol , in good agreement with the theoretical value of 7.3 kJ mol , and AS —8.37 0.15 kJ moP. ... 

An ah initio calculation has been made of the vibrational wavenumbers for the OCCN radical and its cation, OCCN. Gas-phase IR spectroscopy was used to characterise the unstable chlomitrile oxide, CICNO, with Vi (VasCNO) at 2219 cm and V2 (VsCNO) at 1350/1360 cm k vCN (V3) parameters were reported for isotopomers of BrCN, e. g. for 2198.310496(10) cm ... 

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