Photoelectron spectrum cyclopropane

Figure 1. Potential energy diagram for cyclopropane in its ground state ( A/) and the two lowest states of its radical cation ( A, and 82). The vertical transition yields two bands (Jahn-Teller split) in the photoelectron spectrum.

Cyclopropane, the simplest strained ring system, continues to be subject to intense and detailed scrutiny by a variety of techniques. Its photoelectron spectrum. 

FIGURE 6. The He(I) photoelectron spectrum of cyclopropane . A large Jahn-Teller splitting is evident in the pair of bands labelled 3e and a smaller one is suggested by the shape of the le" band. Koopmans theorem is assumed to give the correct sequence of ionization energies... 

The He(I) photoelectron spectrum of cyclopropane is given in Figure 6 (see also Table 1). 

FIGURE 10. The He(I) photoelectron spectrum of 4 which, like cyclopropane, has Da, symmetry. A pair of bands at 8.67 and 9.16 eV are tentatively assigned to 7e, the Jahn-Teller effect causing their separation from each other... 

In Fig. 2 we compare the photoelectron spectrum of cyclopropane s with results obtained from calculations using Koopmans theorem (-ej ") and by considering... 

The crystal structure of 2,2,2, 2 -tetrachloro-3,3,3, 3 -tetramethyl-1,1 -bicyclopropyl has appearedand the photoelectron spectrum of parent l,r-bicyclopropyl has been analysed. The present molecule shows strong conformationally dependent conjugative interaction of the Walsh orbitals of approximately the same magnitude as the interaction between the double bonds of buta-1,3-diene. However, in sterically fixed disubstituted bicyclopropyls the substituents considerably reduce this interaction. Steric potential curves for several bicyclopropyls and substituted cyclopropanes have... 

The UV spectrum of cyclopropane is quite different from those of the alkanes we have examined so far. Whereas acyclic alkanes and cyclic alkanes other than cyclopropane and cyclobutane have only Rydberg bands in the lower frequency (and photo chemically important) part of the spectrum, for cyclopropane the lowest Rydberg bands intermingle with bands due to valence-shell transitions. Two structured bands at 63000 and 78000 cm (159 and 128 nm) have been assigned to the 3e a,3p) and (3e o,4p) transitions on the grounds of the similarity of their vibrational fine structure with that of the respective photoelectron bands and their term values. Two other bands, near 70000 cm (143 nm) and 83000 cm (120 nm)... 

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