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

Question

The compound C60 (MW = 720), also know as Buckminsterfullerene 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 gas. The molecule is spherical with 32 faces, 12 of which are pentagons and 20 of which are hexagons. The molecule displays a single resonance in^13C 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: a) Calculate the intensity of the M + 1 peak of C60 as a percent of the molecular ion peak (m/z 720 = 100%). b) Would you expect to see a significant M + 2 peak? Explain c) Explain why the^13C NMR only shows one resonance. d) Propose a structure for the 724 molecular weight product. Note that you needn't draw out the full structure; simply explain it in a sentence.

Explanation / Answer

The molecular ion peak (M) is due to the mass of 60 12C carbon atoms present in C-60. In M+1 peak, one 12C is replaced by heavier isotope 13C. The relative abundance of 12C in nature is 98.9% and 13C is 1.1%.

So, the intensity of M+1 peak is (1.1×100/ 98.9)= 1.11%

For M+2 peak one 12C is replaced by one 14C. The abundance of 14C in nature is almost negligible and hence the intensity of M+2 peak is very very less. Practically no M+2 peak is observed.

The C60 molecule consists of 60 carbon atoms which form 12 pentagons and a complete spherical shape. All the carbon atoms are chemically equivalent beacuse of the spherical shape all the carbons are surrounded by same chemical environment. For the reason 13C NMR shows only one peak due to the presence of all chemically equivalent carbons.

In molecule with molecular weight 724, 4 H atoms are attached to Buckminster fuller energy. It is possible if two attached pentagons open up and a hole is created in the sphere. Each opened up Pentagon contains two carbon atoms, each of which is attached to one hydrogen atom.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.