Knowledge Bank

The electronic absorption spectra of the cyanogen halides, XCN with $X=C\ell$, Br and I, are presented in the range $3100-1050\backslash AA$. A comparison of the spectra of the cyanogen halides with those of the hydrogen and methyl halides shows that intravalence transitions are responsible for the differences in the electronic spectra of these species. An MO scheme that reliably predicts both the observed electronic spectroscopy and photochemistry is presented.