CO stretch

Owrutsky J C, Li M, Locke B and Hochstrasser R M 1995 Vibrational relaxation of the CO stretch vibration in hemoglobin-CO, myoglobin-CO, and protoheme-CO J. Rhys. Chem. 99 4842-6... 

All classes 1300-1050 causes shift to lower frequency than the normal ester. The C=C band is strong and is usually near 1630 cm k Usually two strong bands due to CO stretch-... 

Commonly used descriptions for these vibrations are (i) symmetric CH-stretch, (ii) antisymmetric CH-stretch, (iii) CH2-scissors, (iv) CH2-rock, (v) CO-stretch, (vi) out-of-plane bend. 

The CO stretch in the infrared spectra of carbonyl compounds gives rise to a strong absorption around 1700 cm , and is often used as a diagnostic. 

Examine each of the vibrational motions for acetone, and identify the motion corresponding to the CO stretch. What is its frequency Are there any other vibrations which have very similar frequencies Does your result have implications for the use of the CO stretching frequency as a diagnostic for carbonyl compounds Elaborate. Does the CO stretching frequency involve significant motion of any atoms other than the two which make up the carbonyl group Rationalize your observation. 

Vibrational spectroscopy has generally been applied to Si—M complexes in order to assign Si—M, M—Cl, M—P, or M—CO stretching mode(s). 

Another way to monitor the expected changes in the metal electronic structure is to look at the adsorbed molecules, which are sensitive in their properties to the changes in the electronic structure of surface metal atoms. Such a molecule is CO and the frequency of the CO stretch vibrations ( v(CO)) is a sensitive detector of the direct- and back-donation upon adsorption of CO. It has been reported, that v(CO) decreases for the VIII group metal by alloying of Pd with Ag (22), Ni with Cu (23), but also when mixing Ni with Co (24). This has been first explained (25) as an indication for an increased backdonation due to an assumed electron shift Cu Pt,... 

Fig. 1.11 Variation in the average CO stretching frequency and in the redox potential from [74]...

More significant is to change the nature of the C and C substituents. Remaining in the class of [IrCl(CO)2(NHC)] complexes, the replacement of the H atoms on the C and C atoms of the IPr complex by Cl atoms resulted in the rather high shift of the average CO stretching frequency from 2023.9 to 2028.3 cm", see Fig. 1.12a [30], Similar effects have been found in the closely related [RhCl(CO)3(NHC)]... 

The 2-methylthio-3-substituted quinazolin-4(3H)-one 3 was obtained by dissolving 4 in 2% alcoholic sodium hydroxide solution and methylating with dimethylsulfate whilst stirring at room temperature (yield 88%, m.p 124-126 C). The IR spectrum of 3 showed the disappearance of the amino (NH) and thioxo (CS) stretching signals of the starting materials. It showed a peak for carbonyl (CO) stretching at 1680 cm The NMR spectriun of com-... 

The IR spectra of carbohydrazide 9 showed absorption bands at 3317 cm (OH,Hydrazide NH2), 3269 cm (aromatic CH), 1711 cm (CO stretching), and 1621-1640 cm (CO-NH-NH2 groups). The H NMR spectra exhibited a singlet due to the CONHNH2, NH proton at 9.32 ppm. Methylene protons resonated as a singlet at 4.23 ppm. The structures of the products lOa-1 were inferred from their analytical and spectral data. Thus, their IR spectra showed characteristic absorption bands at 3400-3240 cm (NH,OH), 1710-1700 cm (lactone CO), and NHCO at 1650-1600 cm . ... 

Figure 11. Infrared spectrum of CO adsorption at 295K for the Pt/SBA-15 catalyst series (a) 2.33% Pt(1.7nm)/SBA-15, (b) 2.69% Pt(2.9 nm)/SBA-15, (c) 2.62% Pt(3.6nm)/SBA-15, and (d) 2.86% Pt(7.1 nm)/SBA-15. Inset is the peak position and FWHM of the atop CO stretching vibration as a function of particle size at room temperature. Peak heights have been modified for clarity [16]. (Reprinted from Ref [16], 2006, with permission from American Chemical Society.)...

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