Other structures of 3-MRs

Miriam Kami, Yitzhak Apeloig, Jurgen Kapp and Paul von R. Schleyer 

TABLE 18. Relative energies (AEy kcalmol l) and geometries (pm, deg) of three-membered rings and their nonclassical H-bridged isomersa 

A notable property of silole is its high electron-accepting ability due to the low-lying LUMO, which is ascribed to the orbital interaction between the a orbitals of the two exocyclic Si—R a bonds with the n orbital of the butadiene moiety212-215 216. The dependence of the LUMO energy on M has not yet been studied. 

Experimental studies of 21, R = Ph, R = Me show strong dependence of the emission maxima on the identity of M. Thus, 21, M = Si, emits at longer wavelengths than 21, M = Ge, while 21, M = Sn does not emit at all. On the other hand, the emission maxima of 21, R = R = Ph are invariant to the change in M. It was proposed, based 

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