Molecular and electronic structure of zwitterionic diamino-meta-quinonoid molecules |
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| Authors: | HUNG THANH LE PHAM CAM NAM VAN LUONG DAO TAMÁS VESZPRÉMI MINH THO NGUYEN |
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| Institution: | 1. Department of Chemistry , University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium;2. Group of Computational Chemistry, Faculty of Chemical Engineering , HoChiMinh City University of Technology , Vietnam;3. Faculty of Chemical Engineering , University of Danang , Vietnam;4. Group of Computational Chemistry, Faculty of Chemical Engineering , HoChiMinh City University of Technology , Vietnam;5. Department of Inorganic Chemistry , University of Technology and Economics , Gellert ter 4, H-1521, Budapest, Hungary;6. Department of Chemistry , University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium |
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| Abstract: | Quantum chemical calculations using molecular orbital (HF, CASSCF) and density functional theory (B3LYP) methods, in conjunction with the 6–311 + + G(d,p) basis set, have been applied to investigate the molecular and electronic structure of two diamino-meta-quinonoid molecules 1a and 2a, each containing a six-membered ring coupled with two exocyclic C = O bonds situated in a meta position, along with two amino substituents (NH2 and NH-CH3). It is confirmed that these substituted meta-quinone systems exhibit a zwitterionic structure in which the positively charged N-C-C(H)-C-N subunit, containing the two amino-groups, forms two chemical bonds with the negatively charged O-C-C(H)-C-O subunit. The negative charge amounts to about half of an electron. The charge separation has been approached in terms of geometries, vibrational frequencies, and electronic distribution. The ionization energy for molecule 1a is about 7.8±0.3eV. The quinonoid systems are essentially non-aromatic characterized by the NICS(+1) values of around 1.2 ppm. |
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