The compound C60 (Mw = 720), also know as Buckminsterfullernce or \"Bucky Balls\

Question

The compound C60 (Mw = 720), also know as Buckminsterfullernce or "Bucky Balls" can be isolated from the soot that forms when creating an electric arc between two graphite electrodes in an atmosphere of helium The molecule is spherical with and 20 of which are hexagons. The molecule 32 aces, 12 of which are pentagons In addition to C60 displays a resonance in^13 C NMR. In addition to C60 another compound can be isolated from the soot having the MW of 724. During the formation of the spherical structure, an approximate sphere having a "hole" first forms, and subsequently closes to the final structure. Given the information, answer the following: Calculate the intensity of the M+1 peak of C60 as a percent of the molecular ion peak (m/z 720 = 100%). Would you expect to see a significant M+2 peak? Explain. Explain why the^13 C NMR only shows one resonance. Propose a structure for the 724 molecular weight product. Note that you needn't draw out the structure; simply explain it in a sentence.

Explanation / Answer

a). If the M+/Z peak of appears at 720 is 100 % the one appears at (M+1) peak will be there with an intensity of 0.67 %. since the natural abundance of C13 is 1.1 %.

(The origin of M+1 and M+2 peaks arises as a result of the natural abundance of the isotopes)

If 100 carbon atoms are there in molecule we will get an intensity of 1 %, in this case, 60 C atoms are there and intensity will come as 0.67.

b). No, the probability of M+2 peak is negligible. the abundance ofC14 is less than 0.0001 %. Thus for 60 C atoms, its contribution will not come in the mass spectra

C). Each carbon atom in fullerene is bonded to three other sp2 hybridized C atoms and their chemical environment is similar. thus all the C atom shows only one resonance in C13 NMR

d). In the case of 724 compound, it is bonded to 4 hydrogen atoms it is opened at one end and the symmetry of the system will loose due to the repulsion between hydrogen atoms. This will create in the bulging of the whole system.

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