The compound C60 (MW = 720), also know as Buckminsterfullerene or \"Bucky Balls\
ID: 530639 • Letter: T
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 are between two graphite electrodes in an atmosphere of helium gas. The molecule is spherical with and 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 structure; simply explain it in a sentence.Explanation / Answer
Answer a ) and b)
Relative to M+ ion = 100%, calculation of isotope peaks for C60 Buckminister fluerene (MW 720) can be done in the following way.
Abundance of [M+1] = number of C x 1.1 = 6 0 x 1.1 = 66 %
Abundance of [M+2] = (number of C x 1.1)2 / 200 =(60 x 1.1)2 / 200 = 21.78 = 22 % (rounding off)
Answer (C)
A single line 13C N MR spectrum was reported for C60 Buckminister fluerene which conforms that all 60 carbon atoms are equivalent. and it also predicts a highly symmetrical cage like structure.
Answer (D
C60 Buckminister fluerene has got a speroidal, highly symmetrical and hollow cage like structure identical to that of a soccer ball which was proved by analysing it's e X-ray and electron diffraction, IR, UVNIS, mass spectra and 13C N MR spectrum.
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