Electron spin resonance of cycloheptatrienyl. Auxiliary apparatus
Part I. The ESR spectra of cycloheptatrienyl (CHT) in several crystalline environments at temperatures ranging from 1.5[degrees] to 300[degrees]K and the methods of sample preparation are described in detail. The observed spectra are classified as: (a) High-temperature spectra--eight equally space...
| Summary: | Part I. The ESR spectra of cycloheptatrienyl (CHT) in several crystalline environments at temperatures ranging from 1.5[degrees] to 300[degrees]K and the methods of sample preparation are described in detail.
The observed spectra are classified as:
(a) High-temperature spectra--eight equally spaced lines with splittings of 3.7 to 4 gauss and intensity ratios 1:7:21:35:35:21:7:1.
(b) Low-temperature spectra-highly anisotropic and different for each environment.
The transitions between (a) and (b) are abrupt, and the transition temperatures are different for each environment.
CHT is a planar regular heptagon with an orbitally degenerate ground state. This degeneracy can be removed by a crystalline electric field. The wave functions, after the degeneracy has been removed, are determined by the crystal field. The Jahn-Teller distortion of the ring and the spin-orbit interaction are probably less than 1 cm[superscript -1].
Part II. The low-temperature ESR system used in the study of CHT is described in detail. A simple and effective zone refiner for organic compounds is described.
Abstract of propositions
1. An extremely versatile low-temperature ESR system is described in detail.
2. The vapor phase photolysis of cyclopropene to produce cyclopropenyl radical (C[subscript 3]H[subscript 3]) for study by ESR is proposed.
3. An experiment to measure the pi-electron spin-orbit interaction in CHT is proposed.
4. It is proposed that magnetic rotation spectroscopy be used to search for the second and third triplet states of benzene.
5. Bitropyl-thiourea inclusion compound is proposed as a novel triplet exciton system.
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