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I. Study of molecular orbital degeneracy in C5H5. II. The crystal and molecular structure of cyclopentadiene


Liebling, Gerald R. (1965) I. Study of molecular orbital degeneracy in C5H5. II. The crystal and molecular structure of cyclopentadiene. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/KEZ8-7539.


NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.

Part I. The paramagnetic resonance of the cyclopentadienyl radical C5H5 has been observed in a single oriented crystal of cyclopentadiene at temperatures ranging from 25[degrees]K to 150[degrees]K. The spectra are of two types, high-temperature and low-temperature spectra, with the transition occurring reversibly between 70[degrees]K and 120[degrees]K. The high temperature spectra consist of six equally spaced lines with a splitting of 6.2 gauss and can be accounted for in terms of a uniform spin distribution around the ring and rapid reorientation of the ring in its plane. The low-temperature spectra are slightly anisotropic and can be reasonably well accounted for by a distorted C5H5 radical with a nonuniform spin distribution undergoing rapid reorientation in its molecular plane.

Part II. The crystal structure of cyclopentadiene, C5H6, has been determined from X-ray diffraction photographs made at about -150[degrees]C. The crystals are monoclinic, space group P2[subscript 1]/n, with cell dimensions [...]. Intensities of 70 reflections recorded on four zero-level precession photographs were estimated visually and used in a least-squares refinement of the atomic coordinates. The final R factor for these reflections is 0.10.

The five-membered ring of carbon atoms is planar; the values for the bond distances are in close agreement with those previously determined by electron diffraction techniques.


Proposition 1: A method of constructing semiconductor devices that would operate at very low temperatures is proposed.

Proposition 2: It is proposed that the EPR spectra of x-irradiated trimesic acid be studied for the possibility of observing an aromatic sigma radical.

Proposition 3: Several experiments are proposed that would elucidate the mechanism of carbene addition across a double bond.

Proposition 4: It is proposed that attenuated total reflection spectroscopy can be very useful for studying electrode processes in electrochemical reactions.

Proposition 5: Several EPR experiments are proposed.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • McConnell, Harden M.
Thesis Committee:
  • Unknown, Unknown
Defense Date:3 March 1965
Record Number:CaltechETD:etd-09302002-122910
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3829
Deposited By: Imported from ETD-db
Deposited On:30 Sep 2002
Last Modified:20 Dec 2019 19:19

Thesis Files

PDF (Liebling_g_1965.pdf) - Final Version
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