Carbonyl group carbon—oxygen bond length

Problem 5.11. Using the information already presented in this chapter, compare the carbon-oxygen bond lengths in the carbonyl groups of all of the different carbonyl containing compounds. What conclusion, if any, do you reach ... 

Further analysis of the microwave spectra provides a precise description of the bond lengths and angles (Table 7). The C2C3 bond is unusually long and relatively weak as shown by the reactivity of substituted cyclopropanones in cycloaddition reactions (see Section 4.4). The carbon-oxygen bond is somewhat shorter than the average carbonyl group and this feature is reflected in the infrared properties of cyclopropanones outlined below. 

So in the carbonyl group, the oxygen atom is partially negative and the carbon atom is partially positive. From X-ray experiments, the length of the C = O bond in the carbonyl group is found to be 1.22 A°. 

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