Novel Colored Systems of the “Inverted Triphenylmethylium Dye” Type Containing Nitrogen, Phosphorus, Sulfur and Congeneric Donor Centers

Abstract

Abstract In the course of a fundamental study relating to the question of color and constitution it was found, that a simple HMO-treatment of the isoconjugate resonance system of triphenylmethylium (TPM) dyes1 provides a very variegated scenery for imagining some novel dye systems. Thus, for the archetype of all TPM-dyes, crystal violet, the spectroscopically relevant frontier orbitals show above a core of nine bonding MO's with a limiting energy of s, two nonbonding levels (nb), one slightly bonding (b) and one slightly antibonding (ab) MO, respectively. The occupancy of the frontier orbitals is 6, so that the longest wavelength absorption corresponds to an excitation from a nb-MO to the weakly antibonding MO. One sees at once, that diminuation of the frontier orbital occupancy by 4, leaving only 2 electrons, should generate a new dye system presenting approximatly the same color as crystal violet, since now the longest wavelength absorption would correspond to a transition from the (symmetrically situat...