CO-stretch frequency

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. 

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)]... 

Figure 12.8 CO-saturated electrolyte in the thin cell of Fig. 12.2. (a) CO oxidation the first and second scans are shown, (b) Comparison with the CO stretch frequency shift. (Filled circles denote linear Stark tuning behavior while open circles correspond to deviations from linear behavior during oxidation.)...

It can be understood as one Aj and one Bj mode, assigned on the basis of a local symmetry 78). In comparison to free ethyl acetate, the CO stretching frequency of which lies at 1742 cm 104), this band is shifted by about 50 cm by Mn-0 bonding. 

Kitajima and Tolman have provided estimates of the relative electron-donating properties of poly(pyrazolyl)borato ligands based upon comparisons of the observed p(CO) stretching frequencies of sev-... 

As expected, [TpBut,Me]Zn(i71-0C02Me) [1689 and 1280 cm-1] and [TpButMe]Zn(T71-0C02H) [1675 and 1302 cm-1] exhibit similar r(CO) stretching frequencies, indicative of similar binding modes for the (0C02H) and (0C02Me) ligands. 

Concerning the bonding in these compounds, the observed N2 or CO stretching frequences have to be compared with those in known matrix species such as Me2SiCO [12], SiCO [13], and SiN2 [13] furthermore, calculations on the molecule H2SiCO have to be taken into account [14], The very weak 71-acceptor qualities of 1 are consistent with the observed and calculated data. 

Adsorption of carbon monoxide takes place all over the surface and there is distinct evidence that, at least on nickel, the CO stretching frequency depends upon the coordination number of the nickel atom to which it is attached. Hence, the adsorption of carbon monoxide yields information about the relative numbers of surface atoms with different coordination numbers. This information, howrever, is at best merely of a semiquantitative nature. Steric effects also play a role, as is evidenced by the fact that the subcarbonyl species can be formed only on nickel atoms with a lowr coordination number. 

The characterization of the species was accomplished with the aid of isotopic labeling studies and ab initio calculations. The Be-CO stretching frequency of 2,189.5 cm-1, above that of CO itself in solid argon (2,138.4cm-1) indicates the considerable strength of BeO as a Lewis acid.65... 

The fluorosulfate (C0)Au0S02F has been prepared by thermolysis of [Au(C0)2]+0S02F-,295,296 and isolated as a colorless solid. The carbonyl group shows an unusually high //(CO) stretching frequency at 2,198 cm-1, and the 13C NMR spectrum has a resonance at 174 ppm.297 In HS03F solution, both parameters show solvation effects, suggesting dissociation into solvated [Au(CO)]+ cations (Scheme 73). 

Figure 8 shows a plot of the CO stretching frequency vs. the trans/cis ratio. A good linear plot is obtained. As one can see, the electronic effect exerted by the phosphine ligands on trans/cis is real. Unfortunately, there is a limit as to how far one can take advantage of this effect to further increase the stereoselectivity. 

Figure 1. Bond order vs. CO stretching frequency the curve was determined from data on organic compounds, data for organometallic compounds have been entered on the curve based on observed CO stretching frequencies.

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