Through-bond conjugation

This is a good indication of strong mixing between Si-Si cr orbitals and C = C 7T orbitals with through-bond conjugation as expected. The molecular structure itself was not very much distorted, as evidenced by the X-ray crystallographic analysis shown in Fig. 2. 

The through-bond conjugation with strong ct-tt mixing for tetrasila-cycloocta-l,5-diyne is further demonstrated by photoelectron spectroscopic (15) and ab initio (3-21G basis set) studies (16). 

Pyridinyl radicals are among the best examples of molecules exhibiting through-bond conjugation , with unusual UV-VIS spectra (tkt - m transition) and chemistry (thermal- and photodissociation). 

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