Absorption spectra and structure of benzimidazoquinozalinone derivatives

Infrared and electronic spectroscopy and X-ray fluorescent analysis were used to study the structures of 5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazolin-6- one and its 5-ethyl and carboxy and sulfo derivatives. The latter compounds we obtained for the first time. The ketone and its monocarboxy derivative exist as lactam tautomers, and the sulfo derivative, in the zwitter ion form. Electronic and energy characteristics of the compounds were calculated by the Pariser-Parr-Pople method. © 2008 MAIK Nauka.