Abstract: Relative to the colorless dialkyl ketones the n+ a* transition energies of the yellow monosilyl and the violet disilyl ketones are considerably lowered. To elucidate the influence of R, Si groups on the carbonyl chromophore, vertical ionization energies, charge-transfer maxima, half-wave reduction potentials, and electronic transitions of alkyl and silyl derivatives of phenyl or naphthyl ketones have been measured and assembled in an ...