150192-63-5Relevant articles and documents
Chalcogeno-Substituted Bis-triphenylmethylium Ions of the Inverse Malachite Green Type
Hellwinkel, Dieter,Stahl, Heinz
, p. 521 - 538 (2007/10/02)
The longest wavelength VIS absorptions of the deeply colored CF3CO2H solutions of the 4,4'-chalcogenobis-(triphenylmethylium) ions 4(++), Y2 (Y = O, S, Se, Te) resemble closely those of the corresponding monocationic 4-arylchalcogenotriphenylmethylium systems 5(1+), ArYC6H4C(1+)(C6H5)2, and not those of the structurally directly related 4,4'-bis(arylchalcogeno)triphenylmethylium ions 3(1+), C6H5C(1+)(C6H4YAr)2.This is in striking contrast to the results obtained previously for analogous nitrogen systems, where "inverse", 2(++), RN, and "conventional" malachite green systems 1(+), (Ar2NC6H4)2C(1+)R, yield almost identical λmax values.A rationalization of these observations can be achieved based on the assumption of largely delocalized dications 2(++) versus more or less orthogonal "double monocationic" systems 4B(++), separated due to torsional twist.Whereas the formal push-pull systems 6(+), ArSC6H4YC6H4C(1+)(C6H5)2 (Y = O, S, Se) behaved practically like the corresponding standard systems 5(+), the mono- and bis-triphenylmethylthio-substituted dibenzofuran, dibenzothiophene and thioxanthene derivatives 8(+), 9(++), 10(+) and 11(++) displayed hypsochromic shifts of their color bands relative to their noncyclic analogues which are only partly in accordance with predictions based on a simple frontier orbital Hueckel model.The 1H and 13C NMR spectra of all these cationic species comply with their respective charges. +"--"+ Dyes, Chalcogeno-bis-trityliumions, VIS Spectra, NMR Spectra
