ISSN:
1573-9171
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract 2,2′-Bis[2-(4-dimethylaminophenyl)-5-trimethylammonio-1,3-indandione] diperchlorate and 2,2′-bis[2-(4-dimethylaminophenyl)-5-(2,4,6-triphenylpyridinio)-1,3-indandione] diperchlorate have very definite thermochromic and mechanochromic properties, owing to reversible dissociation into free radicals. The rupture energy of the central bond C2-C2′ in 5-substituted 2,2′'-bis[2-(4-dimethylaminophenyl)-1,3-indandiones] in acetonitrile is 63–75 kJ/mole; in the dimer with the bulky 5-(2,4,6-triphenylpyridinium) substituent, the rupture energy is 51 kJ/mole. The equilibrium constants follow the Hammett equation (p=1.53, acetonitrile, 293 K). Radicals with onium substituents are thermodynamically the most stable of the arylindandionyl radicals that are thus far known, owing to the significant contribution of electrostatic interactions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00957842
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