E. Velcheva, Y. Binev, M. Petrova
Jan 19, 1999
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0
Influential Citations
10
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Journal
Journal of Molecular Structure
Abstract
Abstract The structures of 4-hydroxybenzylidenemalononitrile (HO–C 6 H 4 –CHC(CN) 2 , I ), its oxyanion ( - O–C 6 H 4 –CHC(CN) 2 , II ), cyanide adduct (HO–C 6 H 4 –CH(CN)–C(CN) 2 , III ) and adduct-oxyanion ( - O–C 6 H 4 –CH(CN)–C(CN) 2 , IV ) have been studied by means of both quantitative IR spectra and ab initio force field calculations. The conversion of ( I ) into the anionic species causes strong changes in the IR spectra: decreases in the ν CN frequency down to 110 cm −1 , up to 7-fold increases in the A CN intensity, up to 58 cm −1 ν CN splitting, etc. The charge analysis shows that the intramolecular charge transfer between the electronegative [C(CN) 2 ] and electropositive fragments of ( I ) is 0.34 e − . Nearly 0.6 e − of the oxyanionic charge of ( II ) remains within the oxyphenylene fragment and nearly 0.5 e − of the carbanionic charge of ( III ) delocalizes within the dicyanomethide fragment. The two charges in ( IV ) are spread over the whole species.