Carbon monoxide infrared spectrum

Whereas ATR spectroscopy is most commonly applied in obtaining infrared absorption spectra of opaque materials, reflection-absorption infrared spectroscopy (RAIRS) is usually used to obtain the absorption spectrum of a thin layer of material adsorbed on an opaque metal surface. An example would be carbon monoxide adsorbed on copper. The metal surface may be either in the form of a film or, of greaf imporfance in fhe sfudy of cafalysfs, one of fhe parficular crysfal faces of fhe mefal. 

It must be acknowledged, however, that the determination of the number of the different surface species which are formed during an adsorption process is often more difficult by means of calorimetry than by spectroscopic techniques. This may be phrased differently by saying that the resolution of spectra is usually better than the resolution of thermograms. Progress in data correction and analysis should probably improve the calorimetric results in that respect. The complex interactions with surface cations, anions, and defects which occur when carbon monoxide contacts nickel oxide at room temperature are thus revealed by the modifications of the infrared spectrum of the sample (75) but not by the differential heats of the CO-adsorption (76). Any modification of the nickel-oxide surface which alters its defect structure produces, however, a change of its energy spectrum with respect to carbon monoxide that is more clearly shown by heat-flow calorimetry (77) than by IR spectroscopy. 

The compound ir-allyltricarbonylcobalt has also been made by treating allyl bromide with Na[Co(CO)4] 109, 111). If this reaction is carried out in an atmosphere of carbon monoxide then about one-half mol. of carbon monoxide is absorbed, and the infrared absorption spectrum of the product shows a band at about 1720 cm-1. This band is believed to be due to the presence of but-2-enoyltetraearbonylcobalt. On standing, carbon monoxide is evolved and the ir-allyl complex [Co(7r-C3H6)(CO)3] is formed. These reactions may be summarized as follows ... 

Carbonylchlorocopper(I) is a colorless crystalline substance that decomposes rapidly in the absence of a carbon monoxide atmosphere to give copper(I) chloride and carbon monoxide. The compound is, however, stable for long periods of time if stored under carbon monoxide. Cu(CO)Cl has a polymeric structure,10 which may be described as layers of fused, six-membered, copper-chloride rings in the chair conformation, with terminally bonded carbonyl ligands. The infrared spectrum of Cu(CO)Cl (Nujol mull at 0°C) displays a characteristic large peak at 2127 cm -1 and a vibrational analysis has been reported.13... 

Infrared Spectroscopy. The spectrum of the solid C showed only weak and unresolved hydroxyl bands (Figure 5). The introduction of CO under an equilibrium pressure of 50 torr did not modify the i>oh bands. After evacuation of the carbon monoxide at room temperature, the IR spectrum showed two bands at 2135 and 2110 cm-1 caused by strongly chemisorbed... 

The 1% ethylene-carbon monoxide copolymer was also irradiated in the solid phase (thin film). Compression-molded films were fixed on plates which fitted into the Perkin Elmer 521 infrared spectrophotometer. An infrared spectrum of the polymer could thus be obtained after each period of photolysis without disturbing the film. For photolyses at room temperature and above the plates were mounted in a solid brass cell through which a stream of inert gas could be passed while the cell was being heated. 

On the basis of the mechanism used to explain the band shifts and the ratio of bridged to linear carbon monoxide it is evident that the infrared spectra of chemisorbed carbon monoxide would be useful in studies of the carrier effect. When alumina is used instead of silica as a carrier for platinum the resulting spectrum of chemisorbed carbon monoxide shows that the band due to linear carbon monoxide has shifted to lower frequency and the amount of bridged carbon monoxide is increased (4). This is interpreted as showing that the n-type conductivity of the alumina is sufficient to modify the electronic properties of the platinum. 

Trifluoroacetic acid may be removed from the adduct in vacuo, but it requires prolonged pumping to remove carbon monoxide. The C-0 stretch in the infrared spectrum of CuOaC CF3(CO) occurs at 2155 cm " a value similar to that of 2093 cm for the cyclopentadienyl complex (88). 

The central role of hydroxyl radicals in atmospheric chemistry is well illustrated by examining the atmospheric cycles of methane and carbon monoxide. A quantitative assessment of both of these species was carried out in the 1920s in Belgium by Marcell Migeotte, who detected their absorption lines in the spectrum of infrared solar radiation reaching Earth s surface. 

A number of model systems have attempted to reproduee the anomalous IR spectra of [FeNi]-hydrogenases. Initial efforts focussed on cyanide, carbon monoxide and nitric oxide complexes as these ligands are known to absorb in this portion of the infrared spectrum [69],... 

The compound Re4H4(CO)i2 is a very dark red (green by reflected light) crystalline compound that is somewhat air stable in the solid state but should be stored under nitrogen, especially when in solution. The infrared spectrum in the carbonyl region shows only two bands, 2042 and 1990 cm V The H NMR (CCI4 solution) show a resonance at rl5.08 together with the resonances for the solvent of crystallization. The compound reacts slowly with carbon monoxide and instant-... 

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