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How many \(^{13}\)C NMR signals does C\(_{60}\) exhibit?

Short Answer

Expert verified
C60 exhibits 1 ^{13}C NMR signal due to its high symmetry.

Step by step solution

01

Understanding C60

C60 is a molecule known as a buckminsterfullerene, or a "buckyball," composed of 60 carbon atoms arranged in a spherical structure.
02

Analyzing Molecular Symmetry

C60 has a highly symmetrical structure, with each carbon atom being equivalent due to the icosahedral symmetry of the molecule. This high level of symmetry means that every carbon atom experiences the same electronic environment.
03

Applying NMR Signal Rules

In carbon-13 NMR ( ^{13}C ext{ NMR} ) spectroscopy, the number of signals corresponds to the number of chemically distinct carbon atoms. Because all carbon atoms in C60 are equivalent, they will produce only one unique signal.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Buckminsterfullerene
Buckminsterfullerene, commonly referred to as a "buckyball," is a fascinating molecule composed entirely of carbon atoms. It is scientifically named after the architect Richard Buckminster Fuller due to its resemblance to the geodesic domes he popularized. The molecule is identified as C\(_{60}\), indicating it consists of 60 carbon atoms.

These carbon atoms are arranged in a unique spherical shape reminiscent of a soccer ball. Buckminsterfullerene is part of a broader class of compounds known as fullerenes, characterized by their structure of carbon atoms typically forming a closed mesh. This structure provides buckminsterfullerene with interesting chemical properties and significant stability.

Its structure allows buckminsterfullerene to have diverse applications in fields such as materials science, nanotechnology, and even medicine. The intriguing configuration and stability make it a subject of ongoing research and fascination.
Molecular Symmetry
Molecular symmetry refers to the arrangement of atoms in a molecule such that it exhibits a balanced configuration. For buckminsterfullerene (C\(_{60}\)), this is an excellent example of icosahedral symmetry, which is one of the most complex and complete symmetries in chemistry.

This type of symmetry means that all 60 carbon atoms in the molecule are indistinguishable from each other in terms of their environment and position. Each carbon atom is surrounded by equivalent atoms, leading to a uniform distribution.

Such a symmetrical arrangement impacts the chemical properties of the molecule, including how it resonates under certain conditions, such as in NMR spectroscopy. Symmetry determines the number of distinct signals observed, as atoms in equivalent environments produce identical signals.
Chemical Shift
In NMR spectroscopy, a chemical shift is an essential concept that describes the changes in the resonant frequency of a nucleus relative to a standard reference.

In the context of carbon-13 (\(^{13}\)C) NMR, the chemical shift denotes changes experienced by the carbon atoms due to their differing electronic environments.

The highly symmetrical icosahedral geometry of the buckminsterfullerene means all carbon nuclei are in identical environments. Therefore, they share the same chemical shift, resulting in only one unique NMR signal. This is illustrative of the strong relationship between molecular symmetry and chemical shift, as symmetry dictates the uniformity or diversity of these shifts.
Spectroscopic Analysis
Spectroscopic analysis is a technique used to understand the structure and characteristics of molecules by observing their interaction with electromagnetic radiation. In the field of organic chemistry, NMR spectroscopy is a vital tool for this analysis.

For a molecule like buckminsterfullerene, NMR provides insights into the molecule's structural symmetry and carbon atom environments. \(^{13}\)C NMR spectroscopy is particularly effective for analyzing carbon-based molecules, as it focuses on the carbon-13 isotope, a natural, albeit less abundant form of carbon.

In C\(_{60}\), the symmetry results in a single peak when analyzed through \(^{13}\)C NMR because all carbon atoms are equivalently placed in the structure. This simplicity in spectroscopic analysis is a testament to the molecule's perfect symmetry, allowing researchers to confirm the structural attributes of buckminsterfullerene effectively.

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Most popular questions from this chapter

Treatment of indene with NaNH\(_2\) forms its conjugate base in a Br\(\phi\)nsted- Lowry acid-base reaction. Draw all reasonable resonance structures for indene's conjugate base, and explain why the pK\(_a\) of indene is lower than the pK\(_a\) of most hydrocarbons.

Thymol (molecular formula C\(_{10}\)H\(_{14}\)O ) is the major component of the oil of thyme. Thymol shows IR absorptions at 3500-3200, 3150-2850, 1621 , and 1585 cm\(^{-1}\). The \(^1\)H NMR spectrum of thymol is given below. Propose a possible structure for thymol.

Zolpidem (trade name Ambien) promotes the rapid onset of sleep, making it a widely prescribed drug for treating insomnia. a. In what type of orbital does the lone pair on each N atom in the heterocycle reside? b. Explain why the bicyclic ring system that contains both N atoms is aromatic. c. Draw all reasonable resonance structures for the bicyclic ring system.

Use the inscribed polygon method to show the pattern of molecular orbitals in cyclooctatetraene. a. Label the MOs as bonding, antibonding, or nonbonding. b. Indicate the arrangement of electrons in these orbitals for cyclooctatetraene, and explain why cyclooctatetraene is notaromatic. c. Treatment of cyclooctatetraene with potassium forms a dianion. How many \(\pi\) electrons does this dianion contain? d. How are the \(\pi\) electrons in this dianion arranged in the molecular orbitals? e. Classify the dianion of cyclooctatetraene as aromatic, antiaromatic, or not aromatic, and explain why this is so.

Draw the conjugate bases of pyrrole and cyclopentadiene. Explain why the \(sp^3\) hybridized C - H bond of cyclopentadiene is more acidic than the N - H bond of pyrrole.

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